Water-filling is the power allocation that maximizes the parallel-channel eigen-MIMO informationtheoretic capacity. However, for practical designs, designing for error performance is also important. The
overall uncoded error rate, in a system with water-filled eigen-channels using digital modulation, degrades
through the errors in the data that uses the weaker eigen-channels. This is because in water-filling, a lower
transmit power is allocated (and a lower proportion of the overall capacity) to the weaker eigenchannels.
One general solution is to discard the weaker eigen-channels, but this does still not allow simple control
over the values of, or trade-off between, capacity and the error rate. In this paper a design approach is
presented for the control of, and improvement in, the overall error performance, while maintaining the
ergodic capacity as high as possible
Power allocation for capacity maximization in eigen mimo with output snr cons...Zac Darcy
Water-filling is the power allocation that maximizes the parallel-channel eigen-MIMO information-theoretic capacity. However, for practical designs, designing for error performance is also important. The overall uncoded error rate, in a system with water-filled eigen-channels using digital modulation, degrades through the errors in the data that uses the weaker eigen-channels. This is because in water-filling, a lower transmit power is allocated (and a lower proportion of the overall capacity) to the weaker eigenchannels. One general solution is to discard the weaker eigen-channels, but this does still not allow simple control over the values of, or trade-off between, capacity and the error rate. In this paper a design approach is presented for the control of, and improvement in, the overall error performance, while maintaining the ergodic capacity as high as possible. The approach is direct; the eigen-channel power allocation is optimized for capacity maximization constrained by a desired error performance on the eigenchannels via constraints on their SNRs. A useful feature is that the capacity and the error performance can be managed through the eigen-channel SNR constraint. Statistical simulations with Rayleigh channels quantify the significant SER improvement compared to full eigen-MIMO (maximum number of eigen-channels) with water-filling, when using a fixed modulation set. This set comprises pre-chosen constellations for a constant number of eigen-channels, and this remains fixed for the all the channel realizations, i.e., with time for the time-varying channel. The improvement in error performance is at the expense of a small loss in capacity.
This document summarizes a research paper that proposes a new reduced-rank minimum mean squared error (MMSE) receiver for direct-sequence code division multiple access (DS/CDMA) communications. The proposed receiver partitions the MMSE filter coefficients using a classification algorithm to significantly reduce computational complexity while maintaining good performance. It is shown to perform better than other reduced-rank MMSE receivers using even fewer taps. The paper also proposes an adaptive partition algorithm that can simultaneously update the receiver partition and coefficients with low complexity, suitable for both synchronous and asynchronous systems.
1) The document analyzes how carrier aggregation (CA) in LTE-Advanced affects the total power transmitted by eNodeBs to meet users' quality of service (QoS) requirements.
2) It derives a general expression showing that the eNodeB's total transmit power is inversely proportional to the channel bandwidth and directly proportional to the cell radius and number of users.
3) Numerical analysis of single-cell and multi-cell scenarios show that using two-carrier CA can reduce the eNodeB's required transmit power by around 65% compared to a single carrier, improving energy efficiency.
Design and Implementation of Efficient Analysis and Synthesis QMF Bank for Mu...TELKOMNIKA JOURNAL
The present section deals with a new type of technique for designing an efficient two channel Quadrature Mirror Filter Bank with constant phase in frequency. For achieving the Perfect Reconstruction Condition in Filter bank, an attempt has been made to design the low pass prototype filter with its impulse response and frequency response in three regions namely pass band, stop band and transition band region. With the error in terms of Reconstruction and the attenuation in the stop band as seen in the prototype filter response, one can evaluate the performance of the introduced filter with the help of filter coefficients generated in the design examples that affects the quality of filter bank design under the constraints of Near Perfect Reconstruction Conditions.
PERFORMANCE ENHANCEMENT OF DYNAMIC CHANNEL ALLOCATION IN CELLULAR MOBILE NETW...ijcseit
In cellular mobile communication system the existing dynamic channel allocation scheme suffer from
high blocking probability and forced termination probability. To mitigate this problem, in this paper we
evaluated the performance of dynamic channel allocation scheme based on carrier-to-noise interference
ratio. In our system model, uplink power strength from a call-initiating user to the base station is
examined. This power is provided by the carrier-to-noise ratio (C/N). The channel search is conducted in
the repeated channel numbers of that cell based on the carrier-to-noise ratio so that this system provides
the low blocking probability and initiates large number of calls in dynamic channel allocation
environment. We have presented the momentous performance in blocking probability and forced
termination probability through this research.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
A gateway based energy efficient multi hop routing protocol for wireless sensor networks (WSNs) is
introduced. The main aim of our paper is to design a protocol which minimizes energy consumption.
Gateway nodes are deployed in sensing field.
Adaptive Resource Allocation in MIMO-OFDM Communication Systemijsrd.com
Multiple Input and Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) system have the potential to achieve very high capacity depending on the propagation environment. The objective of this paper is the adaptive resource allocation in MIMOOFDM system using the waterfilling algorithm. Water filling solution is implemented for allocating the power in order to increase the channel capacity. The total system capacity is maximised subject to the constraints on total power, signal to noise ratio, and proportional fairness. Channel is assumed as a flat fading channel and the comparison is made for different 2x2, 2x3, 3x2 and 4x4 MIMO-OFDM systems using waterfilling algorithm with allocated power. Also in order to prove that the MIMOOFDM with waterfilling algorithm provides the best performance a comparison with various SISO - OFDM is done.
Power allocation for capacity maximization in eigen mimo with output snr cons...Zac Darcy
Water-filling is the power allocation that maximizes the parallel-channel eigen-MIMO information-theoretic capacity. However, for practical designs, designing for error performance is also important. The overall uncoded error rate, in a system with water-filled eigen-channels using digital modulation, degrades through the errors in the data that uses the weaker eigen-channels. This is because in water-filling, a lower transmit power is allocated (and a lower proportion of the overall capacity) to the weaker eigenchannels. One general solution is to discard the weaker eigen-channels, but this does still not allow simple control over the values of, or trade-off between, capacity and the error rate. In this paper a design approach is presented for the control of, and improvement in, the overall error performance, while maintaining the ergodic capacity as high as possible. The approach is direct; the eigen-channel power allocation is optimized for capacity maximization constrained by a desired error performance on the eigenchannels via constraints on their SNRs. A useful feature is that the capacity and the error performance can be managed through the eigen-channel SNR constraint. Statistical simulations with Rayleigh channels quantify the significant SER improvement compared to full eigen-MIMO (maximum number of eigen-channels) with water-filling, when using a fixed modulation set. This set comprises pre-chosen constellations for a constant number of eigen-channels, and this remains fixed for the all the channel realizations, i.e., with time for the time-varying channel. The improvement in error performance is at the expense of a small loss in capacity.
This document summarizes a research paper that proposes a new reduced-rank minimum mean squared error (MMSE) receiver for direct-sequence code division multiple access (DS/CDMA) communications. The proposed receiver partitions the MMSE filter coefficients using a classification algorithm to significantly reduce computational complexity while maintaining good performance. It is shown to perform better than other reduced-rank MMSE receivers using even fewer taps. The paper also proposes an adaptive partition algorithm that can simultaneously update the receiver partition and coefficients with low complexity, suitable for both synchronous and asynchronous systems.
1) The document analyzes how carrier aggregation (CA) in LTE-Advanced affects the total power transmitted by eNodeBs to meet users' quality of service (QoS) requirements.
2) It derives a general expression showing that the eNodeB's total transmit power is inversely proportional to the channel bandwidth and directly proportional to the cell radius and number of users.
3) Numerical analysis of single-cell and multi-cell scenarios show that using two-carrier CA can reduce the eNodeB's required transmit power by around 65% compared to a single carrier, improving energy efficiency.
Design and Implementation of Efficient Analysis and Synthesis QMF Bank for Mu...TELKOMNIKA JOURNAL
The present section deals with a new type of technique for designing an efficient two channel Quadrature Mirror Filter Bank with constant phase in frequency. For achieving the Perfect Reconstruction Condition in Filter bank, an attempt has been made to design the low pass prototype filter with its impulse response and frequency response in three regions namely pass band, stop band and transition band region. With the error in terms of Reconstruction and the attenuation in the stop band as seen in the prototype filter response, one can evaluate the performance of the introduced filter with the help of filter coefficients generated in the design examples that affects the quality of filter bank design under the constraints of Near Perfect Reconstruction Conditions.
PERFORMANCE ENHANCEMENT OF DYNAMIC CHANNEL ALLOCATION IN CELLULAR MOBILE NETW...ijcseit
In cellular mobile communication system the existing dynamic channel allocation scheme suffer from
high blocking probability and forced termination probability. To mitigate this problem, in this paper we
evaluated the performance of dynamic channel allocation scheme based on carrier-to-noise interference
ratio. In our system model, uplink power strength from a call-initiating user to the base station is
examined. This power is provided by the carrier-to-noise ratio (C/N). The channel search is conducted in
the repeated channel numbers of that cell based on the carrier-to-noise ratio so that this system provides
the low blocking probability and initiates large number of calls in dynamic channel allocation
environment. We have presented the momentous performance in blocking probability and forced
termination probability through this research.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
A gateway based energy efficient multi hop routing protocol for wireless sensor networks (WSNs) is
introduced. The main aim of our paper is to design a protocol which minimizes energy consumption.
Gateway nodes are deployed in sensing field.
Adaptive Resource Allocation in MIMO-OFDM Communication Systemijsrd.com
Multiple Input and Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) system have the potential to achieve very high capacity depending on the propagation environment. The objective of this paper is the adaptive resource allocation in MIMOOFDM system using the waterfilling algorithm. Water filling solution is implemented for allocating the power in order to increase the channel capacity. The total system capacity is maximised subject to the constraints on total power, signal to noise ratio, and proportional fairness. Channel is assumed as a flat fading channel and the comparison is made for different 2x2, 2x3, 3x2 and 4x4 MIMO-OFDM systems using waterfilling algorithm with allocated power. Also in order to prove that the MIMOOFDM with waterfilling algorithm provides the best performance a comparison with various SISO - OFDM is done.
Maximum Radiated Emissions of Printed Circuit Board Using Analytical Methods IJECEIAES
The rapid progress of technology has imposed significant challenges on Printed Circuit Boards (PCB) designers. Once of those challenges is to satisfy the electromagnetic compatibility (EMC) compliance requirements. For that reason, EMC compliance must be considered earlier at the design stage for time and cost savings. Conventionally, full wave simulation is employed to check whether the designed PCB meets EMC standards or not. However, this method is not a suitable option since it requires intensive computational time and thus increasing the unit cost. This paper describes novel analytical models for estimating the radiated emissions (RE) of PCB. These models can be used to help the circuit designer to modify their circuit based on the maximum allowable RE comparing to the relevant EMC-RE standard limit. Although there are many RE sources on PCB, this paper focuses on the significant source of RE on PCB; namely PCB-traces. The trace geometry, termination impedance, dielectric type, etc. can be specified based on the maximum allowable emissions. The proposed models were verified by comparing the results of the proposed models with both simulation and experimental results. Good agreements were obtained between the analytically computed results and simulation/measurement results with accuracy of ±3dB.
Segment Combination based Approach for Energy- Aware Multipath Communication ...ijsrd.com
Underwater acoustic communication is a technique of sending and receiving message below water. There are several ways of employing such communication but the most common is using hydrophones. Under water communication is difficult due to factors like multi-path propagation, time variations of the channel, small available bandwidth and strong signal attenuation, especially over long ranges. In underwater communication there are low data rates compared to terrestrial communication, since underwater communication uses acoustic waves instead of electromagnetic waves. The data can be collected from the sensor node and transfer the data to the destination. The same source information can be send through multiple paths through the same destination. So the packet bit error rate is high and power and energy consumption for transferring data is high. The bandwidth and the energy can be consumed. And then the packet bit rate is the serious problem in the existing system. It can be overcome by using the segment combination in the hamming code technique. The packet bit rate can be overcome by increasing the number of paths. The number of paths can be increased based on calculating the cost. For calculating the cost, least cost algorithm is used. And based on the minimum cost path, the path is chosen and data is transferred to the same destination.
Power Transient Response of EDFA as a function of Wavelength in the scenario ...ijsrd.com
In this paper power transient is investigated as function of add/drop wavelength and surviving channel wavelength. We have reported that power excursions varies with different wavelength allocations of the add/drop channels. Transient response is reduced by 73.39% in case when add/drop channels are taken in L band instead of C band. Also power transient response is calculated as a function of wavelengths of surviving channel. It has been observed that at higher wavelengths power excursions are less than at shorter wavelengths of C band.
Energy efficient load balanced routing protocol for wireless sensor networkscsandit
Telecommunications is increasingly vital to the society at large, and has become essential to
business, academic, as well as social activities. Due to the necessity to have access to
telecommunications, the deployment requires regulations and policy. Otherwise, the deployment
of the infrastructures would contribute to environment, and human complexities rather than
ease of use.
However, the formulation of telecommunication infrastructure deployment regulation and
policy involve agents such as people and processes. The roles of the agents are critical, and are
not as easy as it meant to belief. This could be attributed to different factors, as they produce
and reproduce themselves overtime.
This paper presents the result of a study which focused on the roles of agents in the formulation
of telecommunication infrastructures deployment regulation and policy. In the study, the
interactions that take place amongst human and non-human agents were investigated. The study
employed the duality of structure, of Structuration theory as lens to understand the effectiveness
of interactions in the formulation of regulations, and how policy is used to facilitate the
deployment of telecommunications infrastructure in the South African environment.
B ENCHMARKING OF C ELL T HROUGHPUT U SING P ROPORTIONAL F AIR S CHEDULE...ijwmn
The proportional fair (PF) scheduling algorithm com
promises between cell throughput and fairness. Many
research findings have been published by various re
searchers about PF algorithm based on mathematical
model and simulations. In this paper we have taken
the practical route to analyse the algorithm based
on
three types of subscription. In this benchmarking s
tudy, the user subscriptions are differentiated as
Gold,
Silver and Bronze schemes and they are provisioned
with certain throughputs. Apart from subscriptions
plans, the channel condition also plays a major rol
e in determining the throughput. So in order to ens
ure
fairness among different subscriptions even in the
bad channel conditions and to deliver the provision
ed
throughputs certain priorities are attached with th
e subscriptions. As per the subscription plans Gold
subscribers are assigned with 50% of the speed offe
red by the network as maximum based on CAT3 speed
(100 Mbps in DL and 50 Mbps in UL), Silver is assig
ned with 25% of the max speed and Bronze is
assigned with 12% of the max speed. The priorities
assigned to subscribers determines the fairness in
the
unfavourable channel conditions - Bronze (high), Si
lver and Gold (medium). In this paper, an
benchmarking tests have been performed with all of
three types of subscribers for nearly two hours in
the
live single cell network without any heterogeneous
cells influencing it. Furthermore, the results are
compared with the simulation results.
Optimized Cluster Establishment and Cluster-Head Selection Approach in WSNIJCNCJournal
In recent years, limited resources of user products and energy-saving are recognized as the major challenges of Wireless Sensor Networks (WSNs). Clustering is a practical technique that can reduce all energy consumption and provide stability of workload that causes a larger difference in energy depletion among other nodes and cluster heads (CHs). In addition, clustering is the solution of energy-efficient for maximizing the network longevity and improvising energy efficiency. In this paper, a novel OCE-CHS (Optimized Cluster Establishment and Cluster-Head Selection) approach for sensor nodes is represented to improvise the packet success ratio and reduce the average energy-dissipation. The main contribution of this paper is categorized into two processes, first, the clustering algorithm is improvised that periodically chooses the optimal set of the CHs according to the speed of the average node and average-node energy. This is considerably distinguished from node-based clustering that utilizes a distributed clustering algorithm to choose CHs based on the speed of the current node and remaining node energy. Second, more than one factor is assumed for the detached node to join the optimal cluster. In the result section, we discuss our clustering protocols implementation of optimal CH-selection to evade the death of SNs, maximizing throughput, and further improvise the network lifetime by minimizing energy consumption.
Performance Analysis of A Ds-Cdma System by using Rayleigh and Nakagami-M Fad...IRJET Journal
1) The document analyzes the performance of a DS-CDMA system using Rayleigh and Nakagami-M fading channels.
2) It studies expressions for signal-to-noise plus interference ratio with and without receive diversity under Nakagami-m fading.
3) The analysis is extended to a Rake receiver with maximal ratio combining technique and multiple receive antennas to determine the improvement in bit error rate and receiver sensitivity due to diversity.
Improved Algorithm for Throughput Maximization in MC-CDMAVLSICS Design
The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very significant downlink multiple access technique for high-rate data transmission in the fourth generation wireless communication systems. By means of efficient resource allocation higher data rate i.e. throughput can be achieved. This paper evaluates the performance of group (subchannel) allocation criteria employed in downlink transmission, which results in throughput maximization. Proposed algorithm gives the modified technique of sub channel allocation in the downlink transmission of MC-CDMA systems. Simulation are carried out for all the three combining schemes, results shows that for the given power and BER proposed algorithm comparatively gives far better results .
This document discusses adaptive communication techniques using soft computing methods. It proposes using Ant Colony Optimization (ACO) combined with a Fuzzy Rule Base System (FRBS) for adaptive coding, modulation, and power allocation in an Orthogonal Frequency Division Multiplexing (OFDM) system. It compares the proposed approach to other techniques like Simulated Annealing and FRBS, and to a fixed power scheme. The key contributions of the paper are applying ACO and FRBS together for adaptive parameter selection in OFDM to maximize capacity while meeting power and bit error rate constraints.
Energy efficient and reliable communication in IEEE 802.15.6 IR UWB WBANaravind m t
This paper presents an exhaustive study on the use of one-relay and two-relay cooperative communication schemes and 2-hop communication scheme for improving the energy efficiency and reliability of ultra-wideband based wireless body area networks (UWB WBANs). Various investigations have been performed to study the impact of the parameters like packet size, hop distance, transmit power and channel error rate on the energy efficiency and reliability. An optimal packet size is obtained for the maximization of energy efficiency for both on-body communication and in-body communication. The analytical and simulation results show enhanced reliability with cooperative communication than direct communication and 2-hop communication, for all values of source to destination distances. The results also depict a threshold behaviour for energy efficiency which separates the hoplength for direct transmission from the hoplength where cooperation and 2-hop communication will be useful. The simulation results reveal that if the channel conditions are poor, when the source to destination distance is larger than the threshold value, 2-hop communication gives higher energy efficiency compared with direct and cooperative communications.
GPS Enabled Energy Efficient Routing for ManetCSCJournals
In this paper, we propose an energy aware reactive approach by introducing energy and distance based threshold criteria. Cross Layer interaction is exploited the performance of physical layer which leads to significant improvement in the energy efficiency of a network.
Peak to Average Power Ratio Reduction in Mc Cdma System by Using Pulse Shapin...IOSR Journals
Abstract: One of the drawback of multicarrier code division multiple access (MC CDMA) is the high peak to
average power ratio (PAPR). In this paper A novel scheme based on pulse shaping described for PAPR
reduction. Here three different pulse shaping filters (Raised cosine, Sinc power pulse and Nyqist pulse) are
described for PAPR reduction in MC CDMA system. The method is based on the proper selection of the pulses
for shaping the different sub carriers of the MC CDMA modulation scheme. It is shown by computer simulation
that the scheme achieves the significant improvement in PAPR reduction in MC CDMA system. Its
implementation complexity is much low in comparison to the previous published methods. Thus pulse shaping
technique can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR. In
computer simulation It is observed that by using nyquist pulse near about 6.8 db PAPR is obtained. Which is
considerable PAPR reduction than a PAPR value of Original MC CDMA signal
Keywords: MC CDMA, PAPR, PULSE SHAPING, BPSK
Trilateration-based localization (TBL) has become a corner stone of modern technology. This study
formulates the concern on how wireless sensor networks can take advantage of the computational
intelligent techniques using both single- and multi-objective particle swarm optimization (PSO) with an
overall aim of concurrently minimizing the required time for localization, minimizing energy consumed
during localization, and maximizing the number of nodes fully localized through the adjustment of wireless
sensor transmission ranges while using TBL process. A parameter-study of the applied PSO variants is
performed, leading to results that show algorithmic improvements of up to 32% in the evaluated objectives.
An Efficient Resource Utilization Scheme for Video Transmission over Wireless...ijsrd.com
In this paper we propose an energy efficient video transmission strategy for wireless sensor networks, which combines wavelet-based image decomposition and cooperative communication. The proposed scheme uses the selective decode and forward (SDF) cooperation, so that a relay node collaborates with the source by forwarding only a lower-resolution version of the original video, obtained via discrete wavelet transform (DWT). We show that the proposed SDF-DWT strategy is more energy efficient than non-cooperative single-hop and multi-hop, also outperforming the regular SDF scheme. In addition, we show that our method can achieve the energy efficiency of incremental DF (IDF), without the need of a feedback channel.
A NOVEL HYBRID OPPORTUNISTIC SCALABLE ENERGY EFFICIENT ROUTING DESIGN FOR LOW...IJCNCJournal
Opportunistic Routing (OR) scheme increases the transmission reliability despite the lossy wireless radio links by exploiting the broadcast nature of the wireless medium. However, OR schemes in low power Wireless Sensor Network (WSN) leads to energy drain in constrained sensor nodes due to constant
overhearing, periodic beaconing for Neighbourhood Management (NM) and increase in packet header length to append priority wise sorted Forwarding Candidates Set (FCS) prior to data transmission. The timer-based coordination mechanism incurs the least overhead to coordinate among the FCS that has successfully received the data packet for relaying the data in a multi-hop manner. This timer-based mechanism suffers from duplicate transmissions if the FCS is either not carefully selected or coordinated. The focus of this work is to propose a hybrid opportunistic energy efficient routing design for large scale, low power and lossy WSN. This design avoids periodic 'hello' beacons for NM, limits constant overhearing and increase in packet header length. There are two modes of operation i) opportunistic ii) unicast mode. The sender node adopts opportunistic forwarding for its initial data packet transmission and instead of pre-computing the FCS, it is dynamically computed in a completely distributed manner. The
eligible nodes to be part of FCS will be neighbour nodes at lower corona level than the sender with respect to the sink and remaining energy above the minimum threshold. The nodes part of FCS based on crosslayered multi-metrics and fuzzy decision logic determines its priority level to compute Dynamic Holding
Delay (DHD) for effective timer coordination. The differentiated back off implementation along with DHD enables the higher priority candidate that had received data packet to forward the packet first and facilitates others to cancel its timer upon overhearing. The sender node switches to unicast mode of
forwarding for successive transmissions by choosing the forwarding node with maximum trust value as it
denotes the stability of the temporally varying link with respect to the forwarder. The sender node will revert to opportunistic mode to increase transmission reliability in case of link-level transmission error or no trustworthy forwarders. Simulation results in NS2 show significant increase in Packet Delivery Ratio (PDR),decrease in both average energy consumption per node and Normalized Energy Consumption (NEC) per packet in comparison with existing protocols.
This document discusses improving network lifetime in ad hoc networks through energy efficient routing. It proposes a routing mechanism that considers both the minimum hop count and residual energy of nodes to select paths for data transmission. The key points are:
1) Existing routing mechanisms only consider hop count and do not account for node energy levels, which can reduce network lifetime.
2) The proposed mechanism selects paths based on both minimum hop count and maximum residual energy of nodes. This avoids overusing certain nodes and depleting their energy.
3) It describes the routing procedure, energy efficient data transmission, and modules for calculating packet numbers, inserting values in routing lists, selecting paths, and handling residual routing when nodes have low energy.
Novel Position Estimation using Differential Timing Information for Asynchron...IJCNCJournal
Positioning techniques have been a common objective since the early development of wireless networks. However, current positioning methods in cellular networks, for instance, are still primarily focused on the use of the Global Navigation Satellite System (GNSS), which has several limitations, like high power drainage and failure in indoor scenarios. This study introduces a novel approach employing standard LTE signaling in order to provide high accuracy positioning estimation. The proposed technique is designed in analogy to the human sound localization system, eliminating the need of having information from three spatially diverse Base Stations (BSs). This is inspired by the perfect human 3D sound localization with two ears. A field study is carried out in a dense urban city to verify the accuracy of the proposed technique, with more than 20 thousand measurement samples collected. The achieved positioning accuracy is meeting the latest Federal Communications Commission (FCC) requirements in the planner dimension.
A Survey of Existing Mechanisms in Energy-Aware Routing In MANETsEditor IJCATR
A mobile ad hoc network (MANET) is a distributed and Self-organized network. In MANET, network topology frequently changes because of high mobility nodes. Mobility of nodes and battery energy depletion are two major factors that cause loss of the discovered routes. battery power depletion causes the nodes to die and loss of the obtained paths and thus affects the network connectivity. Therefore, a routing protocol for energy efficiency should consider all the aspects to manage the energy consumption in the network. so introducing an energy aware routing protocol, is one of the most important issues in MANET. This paper reviews some energy aware routing protocols. The main purpose energy aware protocols are efficiently use of energy, reducing energy consumption and increasing the network lifetime.
Enhancing Performance for Orthogonal Frequency Division Multiplexing in Wirel...IRJET Journal
The document discusses enhancing the performance of Orthogonal Frequency Division Multiplexing (OFDM) in wireless systems. It proposes using a technique called Selective Level Mapping (SLM) to reduce the peak-to-average power ratio (PAPR) of OFDM signals. PAPR reduction is important for OFDM systems to improve power amplifier efficiency. The document describes a "Class-III SLM scheme" that can generate multiple alternative OFDM signal sequences using only one inverse fast Fourier transform, helping to reduce complexity. It proposes a selection method for rotation values that can achieve optimal PAPR reduction while balancing the load across components. Simulation results show the proposed method achieves better PAPR reduction performance than conventional methods
This document summarizes several papers on techniques for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. The papers discuss using techniques like partial transmit sequence (PTS), companding transforms, cross entropy methods, and weighted OFDM signals to reduce PAPR without significantly impacting bit error rate or requiring additional processing at the receiver. Simulation results show these techniques can provide PAPR reduction close to exhaustive search methods while maintaining lower complexity.
Resource Allocation in MIMO – OFDM Communication System under Signal Strength...Kumar Goud
Abstract: - Multiple Inputs and Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) system have the potential to attain high capability on the propagation setting. The aim of this paper is that the adaptive resource allocation in MIMO-OFDM system uses the water filling formula. Water filling answer is enforced for allocating the ability so as to extend the data rate. The overall system capability is maximised subject to the constraints on total power, signal to noise quantitative relation, and proportionality. Channel is assumed as a flat attenuation channel and therefore the comparison is created for various 2×2, 2×3, 3×2 and 4×4 MIMO-OFDM systems and water filling formula with allotted power. Supported the capability contribution from the relaying terminal, a brand new parameter referred to as cooperation constant is introduced as an operate of the relaying sub channel. This parameter is employed to switch the target parameter of the subcarrier allocation procedure. Fairness-oriented [Fading Channel] and throughput-oriented [Near finish Channel] algorithms square measure elite from the literature to check the planned technique. Each algorithms square measure changed to use the mean of cooperation constant within the objective parameter of the subcarrier allocation procedure and shown to own a much better total turnout with none sacrifice.
Keywords - MIMO-OFDM; Water filling Algorithm; Subcarrier Resource Allocation
This document describes a method for maximizing the total throughput of a two-way relay network using orthogonal frequency-division multiplexing (OFDM). The method jointly optimizes subcarrier pairing and relay selection by formulating the problem as a maximum weighted bipartite matching problem, which can be solved in polynomial time. Simulation results show that the proposed method increases total throughput compared to benchmark methods, especially as the number of relays increases. The throughput is evaluated for different numbers of subcarriers and relays to analyze the system's performance under various conditions.
Maximum Radiated Emissions of Printed Circuit Board Using Analytical Methods IJECEIAES
The rapid progress of technology has imposed significant challenges on Printed Circuit Boards (PCB) designers. Once of those challenges is to satisfy the electromagnetic compatibility (EMC) compliance requirements. For that reason, EMC compliance must be considered earlier at the design stage for time and cost savings. Conventionally, full wave simulation is employed to check whether the designed PCB meets EMC standards or not. However, this method is not a suitable option since it requires intensive computational time and thus increasing the unit cost. This paper describes novel analytical models for estimating the radiated emissions (RE) of PCB. These models can be used to help the circuit designer to modify their circuit based on the maximum allowable RE comparing to the relevant EMC-RE standard limit. Although there are many RE sources on PCB, this paper focuses on the significant source of RE on PCB; namely PCB-traces. The trace geometry, termination impedance, dielectric type, etc. can be specified based on the maximum allowable emissions. The proposed models were verified by comparing the results of the proposed models with both simulation and experimental results. Good agreements were obtained between the analytically computed results and simulation/measurement results with accuracy of ±3dB.
Segment Combination based Approach for Energy- Aware Multipath Communication ...ijsrd.com
Underwater acoustic communication is a technique of sending and receiving message below water. There are several ways of employing such communication but the most common is using hydrophones. Under water communication is difficult due to factors like multi-path propagation, time variations of the channel, small available bandwidth and strong signal attenuation, especially over long ranges. In underwater communication there are low data rates compared to terrestrial communication, since underwater communication uses acoustic waves instead of electromagnetic waves. The data can be collected from the sensor node and transfer the data to the destination. The same source information can be send through multiple paths through the same destination. So the packet bit error rate is high and power and energy consumption for transferring data is high. The bandwidth and the energy can be consumed. And then the packet bit rate is the serious problem in the existing system. It can be overcome by using the segment combination in the hamming code technique. The packet bit rate can be overcome by increasing the number of paths. The number of paths can be increased based on calculating the cost. For calculating the cost, least cost algorithm is used. And based on the minimum cost path, the path is chosen and data is transferred to the same destination.
Power Transient Response of EDFA as a function of Wavelength in the scenario ...ijsrd.com
In this paper power transient is investigated as function of add/drop wavelength and surviving channel wavelength. We have reported that power excursions varies with different wavelength allocations of the add/drop channels. Transient response is reduced by 73.39% in case when add/drop channels are taken in L band instead of C band. Also power transient response is calculated as a function of wavelengths of surviving channel. It has been observed that at higher wavelengths power excursions are less than at shorter wavelengths of C band.
Energy efficient load balanced routing protocol for wireless sensor networkscsandit
Telecommunications is increasingly vital to the society at large, and has become essential to
business, academic, as well as social activities. Due to the necessity to have access to
telecommunications, the deployment requires regulations and policy. Otherwise, the deployment
of the infrastructures would contribute to environment, and human complexities rather than
ease of use.
However, the formulation of telecommunication infrastructure deployment regulation and
policy involve agents such as people and processes. The roles of the agents are critical, and are
not as easy as it meant to belief. This could be attributed to different factors, as they produce
and reproduce themselves overtime.
This paper presents the result of a study which focused on the roles of agents in the formulation
of telecommunication infrastructures deployment regulation and policy. In the study, the
interactions that take place amongst human and non-human agents were investigated. The study
employed the duality of structure, of Structuration theory as lens to understand the effectiveness
of interactions in the formulation of regulations, and how policy is used to facilitate the
deployment of telecommunications infrastructure in the South African environment.
B ENCHMARKING OF C ELL T HROUGHPUT U SING P ROPORTIONAL F AIR S CHEDULE...ijwmn
The proportional fair (PF) scheduling algorithm com
promises between cell throughput and fairness. Many
research findings have been published by various re
searchers about PF algorithm based on mathematical
model and simulations. In this paper we have taken
the practical route to analyse the algorithm based
on
three types of subscription. In this benchmarking s
tudy, the user subscriptions are differentiated as
Gold,
Silver and Bronze schemes and they are provisioned
with certain throughputs. Apart from subscriptions
plans, the channel condition also plays a major rol
e in determining the throughput. So in order to ens
ure
fairness among different subscriptions even in the
bad channel conditions and to deliver the provision
ed
throughputs certain priorities are attached with th
e subscriptions. As per the subscription plans Gold
subscribers are assigned with 50% of the speed offe
red by the network as maximum based on CAT3 speed
(100 Mbps in DL and 50 Mbps in UL), Silver is assig
ned with 25% of the max speed and Bronze is
assigned with 12% of the max speed. The priorities
assigned to subscribers determines the fairness in
the
unfavourable channel conditions - Bronze (high), Si
lver and Gold (medium). In this paper, an
benchmarking tests have been performed with all of
three types of subscribers for nearly two hours in
the
live single cell network without any heterogeneous
cells influencing it. Furthermore, the results are
compared with the simulation results.
Optimized Cluster Establishment and Cluster-Head Selection Approach in WSNIJCNCJournal
In recent years, limited resources of user products and energy-saving are recognized as the major challenges of Wireless Sensor Networks (WSNs). Clustering is a practical technique that can reduce all energy consumption and provide stability of workload that causes a larger difference in energy depletion among other nodes and cluster heads (CHs). In addition, clustering is the solution of energy-efficient for maximizing the network longevity and improvising energy efficiency. In this paper, a novel OCE-CHS (Optimized Cluster Establishment and Cluster-Head Selection) approach for sensor nodes is represented to improvise the packet success ratio and reduce the average energy-dissipation. The main contribution of this paper is categorized into two processes, first, the clustering algorithm is improvised that periodically chooses the optimal set of the CHs according to the speed of the average node and average-node energy. This is considerably distinguished from node-based clustering that utilizes a distributed clustering algorithm to choose CHs based on the speed of the current node and remaining node energy. Second, more than one factor is assumed for the detached node to join the optimal cluster. In the result section, we discuss our clustering protocols implementation of optimal CH-selection to evade the death of SNs, maximizing throughput, and further improvise the network lifetime by minimizing energy consumption.
Performance Analysis of A Ds-Cdma System by using Rayleigh and Nakagami-M Fad...IRJET Journal
1) The document analyzes the performance of a DS-CDMA system using Rayleigh and Nakagami-M fading channels.
2) It studies expressions for signal-to-noise plus interference ratio with and without receive diversity under Nakagami-m fading.
3) The analysis is extended to a Rake receiver with maximal ratio combining technique and multiple receive antennas to determine the improvement in bit error rate and receiver sensitivity due to diversity.
Improved Algorithm for Throughput Maximization in MC-CDMAVLSICS Design
The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very significant downlink multiple access technique for high-rate data transmission in the fourth generation wireless communication systems. By means of efficient resource allocation higher data rate i.e. throughput can be achieved. This paper evaluates the performance of group (subchannel) allocation criteria employed in downlink transmission, which results in throughput maximization. Proposed algorithm gives the modified technique of sub channel allocation in the downlink transmission of MC-CDMA systems. Simulation are carried out for all the three combining schemes, results shows that for the given power and BER proposed algorithm comparatively gives far better results .
This document discusses adaptive communication techniques using soft computing methods. It proposes using Ant Colony Optimization (ACO) combined with a Fuzzy Rule Base System (FRBS) for adaptive coding, modulation, and power allocation in an Orthogonal Frequency Division Multiplexing (OFDM) system. It compares the proposed approach to other techniques like Simulated Annealing and FRBS, and to a fixed power scheme. The key contributions of the paper are applying ACO and FRBS together for adaptive parameter selection in OFDM to maximize capacity while meeting power and bit error rate constraints.
Energy efficient and reliable communication in IEEE 802.15.6 IR UWB WBANaravind m t
This paper presents an exhaustive study on the use of one-relay and two-relay cooperative communication schemes and 2-hop communication scheme for improving the energy efficiency and reliability of ultra-wideband based wireless body area networks (UWB WBANs). Various investigations have been performed to study the impact of the parameters like packet size, hop distance, transmit power and channel error rate on the energy efficiency and reliability. An optimal packet size is obtained for the maximization of energy efficiency for both on-body communication and in-body communication. The analytical and simulation results show enhanced reliability with cooperative communication than direct communication and 2-hop communication, for all values of source to destination distances. The results also depict a threshold behaviour for energy efficiency which separates the hoplength for direct transmission from the hoplength where cooperation and 2-hop communication will be useful. The simulation results reveal that if the channel conditions are poor, when the source to destination distance is larger than the threshold value, 2-hop communication gives higher energy efficiency compared with direct and cooperative communications.
GPS Enabled Energy Efficient Routing for ManetCSCJournals
In this paper, we propose an energy aware reactive approach by introducing energy and distance based threshold criteria. Cross Layer interaction is exploited the performance of physical layer which leads to significant improvement in the energy efficiency of a network.
Peak to Average Power Ratio Reduction in Mc Cdma System by Using Pulse Shapin...IOSR Journals
Abstract: One of the drawback of multicarrier code division multiple access (MC CDMA) is the high peak to
average power ratio (PAPR). In this paper A novel scheme based on pulse shaping described for PAPR
reduction. Here three different pulse shaping filters (Raised cosine, Sinc power pulse and Nyqist pulse) are
described for PAPR reduction in MC CDMA system. The method is based on the proper selection of the pulses
for shaping the different sub carriers of the MC CDMA modulation scheme. It is shown by computer simulation
that the scheme achieves the significant improvement in PAPR reduction in MC CDMA system. Its
implementation complexity is much low in comparison to the previous published methods. Thus pulse shaping
technique can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR. In
computer simulation It is observed that by using nyquist pulse near about 6.8 db PAPR is obtained. Which is
considerable PAPR reduction than a PAPR value of Original MC CDMA signal
Keywords: MC CDMA, PAPR, PULSE SHAPING, BPSK
Trilateration-based localization (TBL) has become a corner stone of modern technology. This study
formulates the concern on how wireless sensor networks can take advantage of the computational
intelligent techniques using both single- and multi-objective particle swarm optimization (PSO) with an
overall aim of concurrently minimizing the required time for localization, minimizing energy consumed
during localization, and maximizing the number of nodes fully localized through the adjustment of wireless
sensor transmission ranges while using TBL process. A parameter-study of the applied PSO variants is
performed, leading to results that show algorithmic improvements of up to 32% in the evaluated objectives.
An Efficient Resource Utilization Scheme for Video Transmission over Wireless...ijsrd.com
In this paper we propose an energy efficient video transmission strategy for wireless sensor networks, which combines wavelet-based image decomposition and cooperative communication. The proposed scheme uses the selective decode and forward (SDF) cooperation, so that a relay node collaborates with the source by forwarding only a lower-resolution version of the original video, obtained via discrete wavelet transform (DWT). We show that the proposed SDF-DWT strategy is more energy efficient than non-cooperative single-hop and multi-hop, also outperforming the regular SDF scheme. In addition, we show that our method can achieve the energy efficiency of incremental DF (IDF), without the need of a feedback channel.
A NOVEL HYBRID OPPORTUNISTIC SCALABLE ENERGY EFFICIENT ROUTING DESIGN FOR LOW...IJCNCJournal
Opportunistic Routing (OR) scheme increases the transmission reliability despite the lossy wireless radio links by exploiting the broadcast nature of the wireless medium. However, OR schemes in low power Wireless Sensor Network (WSN) leads to energy drain in constrained sensor nodes due to constant
overhearing, periodic beaconing for Neighbourhood Management (NM) and increase in packet header length to append priority wise sorted Forwarding Candidates Set (FCS) prior to data transmission. The timer-based coordination mechanism incurs the least overhead to coordinate among the FCS that has successfully received the data packet for relaying the data in a multi-hop manner. This timer-based mechanism suffers from duplicate transmissions if the FCS is either not carefully selected or coordinated. The focus of this work is to propose a hybrid opportunistic energy efficient routing design for large scale, low power and lossy WSN. This design avoids periodic 'hello' beacons for NM, limits constant overhearing and increase in packet header length. There are two modes of operation i) opportunistic ii) unicast mode. The sender node adopts opportunistic forwarding for its initial data packet transmission and instead of pre-computing the FCS, it is dynamically computed in a completely distributed manner. The
eligible nodes to be part of FCS will be neighbour nodes at lower corona level than the sender with respect to the sink and remaining energy above the minimum threshold. The nodes part of FCS based on crosslayered multi-metrics and fuzzy decision logic determines its priority level to compute Dynamic Holding
Delay (DHD) for effective timer coordination. The differentiated back off implementation along with DHD enables the higher priority candidate that had received data packet to forward the packet first and facilitates others to cancel its timer upon overhearing. The sender node switches to unicast mode of
forwarding for successive transmissions by choosing the forwarding node with maximum trust value as it
denotes the stability of the temporally varying link with respect to the forwarder. The sender node will revert to opportunistic mode to increase transmission reliability in case of link-level transmission error or no trustworthy forwarders. Simulation results in NS2 show significant increase in Packet Delivery Ratio (PDR),decrease in both average energy consumption per node and Normalized Energy Consumption (NEC) per packet in comparison with existing protocols.
This document discusses improving network lifetime in ad hoc networks through energy efficient routing. It proposes a routing mechanism that considers both the minimum hop count and residual energy of nodes to select paths for data transmission. The key points are:
1) Existing routing mechanisms only consider hop count and do not account for node energy levels, which can reduce network lifetime.
2) The proposed mechanism selects paths based on both minimum hop count and maximum residual energy of nodes. This avoids overusing certain nodes and depleting their energy.
3) It describes the routing procedure, energy efficient data transmission, and modules for calculating packet numbers, inserting values in routing lists, selecting paths, and handling residual routing when nodes have low energy.
Novel Position Estimation using Differential Timing Information for Asynchron...IJCNCJournal
Positioning techniques have been a common objective since the early development of wireless networks. However, current positioning methods in cellular networks, for instance, are still primarily focused on the use of the Global Navigation Satellite System (GNSS), which has several limitations, like high power drainage and failure in indoor scenarios. This study introduces a novel approach employing standard LTE signaling in order to provide high accuracy positioning estimation. The proposed technique is designed in analogy to the human sound localization system, eliminating the need of having information from three spatially diverse Base Stations (BSs). This is inspired by the perfect human 3D sound localization with two ears. A field study is carried out in a dense urban city to verify the accuracy of the proposed technique, with more than 20 thousand measurement samples collected. The achieved positioning accuracy is meeting the latest Federal Communications Commission (FCC) requirements in the planner dimension.
A Survey of Existing Mechanisms in Energy-Aware Routing In MANETsEditor IJCATR
A mobile ad hoc network (MANET) is a distributed and Self-organized network. In MANET, network topology frequently changes because of high mobility nodes. Mobility of nodes and battery energy depletion are two major factors that cause loss of the discovered routes. battery power depletion causes the nodes to die and loss of the obtained paths and thus affects the network connectivity. Therefore, a routing protocol for energy efficiency should consider all the aspects to manage the energy consumption in the network. so introducing an energy aware routing protocol, is one of the most important issues in MANET. This paper reviews some energy aware routing protocols. The main purpose energy aware protocols are efficiently use of energy, reducing energy consumption and increasing the network lifetime.
Enhancing Performance for Orthogonal Frequency Division Multiplexing in Wirel...IRJET Journal
The document discusses enhancing the performance of Orthogonal Frequency Division Multiplexing (OFDM) in wireless systems. It proposes using a technique called Selective Level Mapping (SLM) to reduce the peak-to-average power ratio (PAPR) of OFDM signals. PAPR reduction is important for OFDM systems to improve power amplifier efficiency. The document describes a "Class-III SLM scheme" that can generate multiple alternative OFDM signal sequences using only one inverse fast Fourier transform, helping to reduce complexity. It proposes a selection method for rotation values that can achieve optimal PAPR reduction while balancing the load across components. Simulation results show the proposed method achieves better PAPR reduction performance than conventional methods
This document summarizes several papers on techniques for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. The papers discuss using techniques like partial transmit sequence (PTS), companding transforms, cross entropy methods, and weighted OFDM signals to reduce PAPR without significantly impacting bit error rate or requiring additional processing at the receiver. Simulation results show these techniques can provide PAPR reduction close to exhaustive search methods while maintaining lower complexity.
Resource Allocation in MIMO – OFDM Communication System under Signal Strength...Kumar Goud
Abstract: - Multiple Inputs and Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) system have the potential to attain high capability on the propagation setting. The aim of this paper is that the adaptive resource allocation in MIMO-OFDM system uses the water filling formula. Water filling answer is enforced for allocating the ability so as to extend the data rate. The overall system capability is maximised subject to the constraints on total power, signal to noise quantitative relation, and proportionality. Channel is assumed as a flat attenuation channel and therefore the comparison is created for various 2×2, 2×3, 3×2 and 4×4 MIMO-OFDM systems and water filling formula with allotted power. Supported the capability contribution from the relaying terminal, a brand new parameter referred to as cooperation constant is introduced as an operate of the relaying sub channel. This parameter is employed to switch the target parameter of the subcarrier allocation procedure. Fairness-oriented [Fading Channel] and throughput-oriented [Near finish Channel] algorithms square measure elite from the literature to check the planned technique. Each algorithms square measure changed to use the mean of cooperation constant within the objective parameter of the subcarrier allocation procedure and shown to own a much better total turnout with none sacrifice.
Keywords - MIMO-OFDM; Water filling Algorithm; Subcarrier Resource Allocation
This document describes a method for maximizing the total throughput of a two-way relay network using orthogonal frequency-division multiplexing (OFDM). The method jointly optimizes subcarrier pairing and relay selection by formulating the problem as a maximum weighted bipartite matching problem, which can be solved in polynomial time. Simulation results show that the proposed method increases total throughput compared to benchmark methods, especially as the number of relays increases. The throughput is evaluated for different numbers of subcarriers and relays to analyze the system's performance under various conditions.
Design of a high frequency low voltage CMOS operational amplifierVLSICS Design
A method is presented in this paper for the design of a high frequency CMOS operational amplifier (OpAmp) which operates at 3V power supply using tsmc 0.18 micron CMOS technology. The OPAMP designed is a two-stage CMOS OPAMP followed by an output buffer. This Operational Transconductance Amplifier (OTA) employs a Miller capacitor and is compensated with a current buffer compensation technique. The unique behaviour of the MOS transistors in saturation region not only allows a designer to work at a low voltage, but also at a high frequency. Designing of two-stage op-amps is a multi-dimensional-optimization problem where optimization of one or more parameters may easily result into degradation of others. The OPAMP is designed to exhibit a unity gain frequency of 2.02GHz and exhibits a gain of 49.02dB with a 60.50 phase margin. As compared to the conventional approach, the proposed compensation method results in a higher unity gain frequency under the same load condition. Design has been carried out in Tanner tools. Simulation results are verified using S-edit and W-edit.
This document analyzes the capacity of MIMO wireless channels when accounting for impairments from physical transceiver hardware limitations. It is shown that when including the effects of transceiver impairments like non-linearities, phase noise, and quantization noise, the capacity of MIMO channels reaches a finite limit as SNR increases, rather than increasing without bound. This results in a zero multiplexing gain, unlike the ideal case without impairments. However, the relative capacity increase from MIMO over single-antenna channels remains at least as large when including impairments. Various figures are presented showing the capacity and multiplexing gain for different channel models and transceiver configurations. The document concludes by stating the analysis provides insights into understanding
Channel feedback scheduling for wireless communicationseSAT Journals
Abstract Opportunistic scheduling can significantly improve wireless network performance by exploiting the underlying channel condition. There has been a lot of work on opportunistic scheduling, but the problem of finding the right feedback mechanism to convey channel information has largely been untouched. In emerging multichannel systems, the per-channel feedback induces a substantial amount of feedback overhead and requires high computational complexity. To reduce the feedback overhead, we consider an opportunistic feedback strategy that activates the channel feedback opportunistically according to the channel condition. Then, we combine the opportunistic feedback with the best-n channel feedback scheme where a mobile user chooses the best n channels and transfers this information to the base station. We analyze the throughput and the amount of channel feedback information for proportionally fair opportunistic scheduling under Rayleigh fading i.i.d. channels. The numerical results confirm that our partial feedback schemes achieve a remarkable reduction in the amount of feedback information without significant throughput degradation, thereby saving the scarce wireless bandwidth and limited battery power.
PERFORMANCE IMPROVEMENT OF NONREGENERATIVE COOPERATIVE RELAY NETWORKS WITH OP...ijwmn
This paper analyzes the performance of cooperative amplify-and-forward (CAF) relay networks that employ both optimal power allocation among nodes based on relay position and adaptive M-QAM/M-PSK modulation in generalized fading environments. The paper develops a unified analytical framework using marginal moment generating functions to derive expressions for average bit error rate, mean achievable spectral efficiency, and outage probability over a range of fading distributions. It applies this framework to analyze CAF relay networks with adaptive modulation over Rice fading channels. The paper also employs an approximate moment generating function to further simplify computation complexity. Finally, it applies the framework to analyze the impact of optimal power allocation based on relay position.
PERFORMANCE IMPROVEMENT OF NONREGENERATIVE COOPERATIVE RELAY NETWORKS WITH OP...ijwmn
This paper analyzes the performance of Channel Side Information (CSI)-assisted cooperative amplify-andforward (CAF) relay networks that employ both the node placement (i.e., relay position) based optimal
power allocation policy among collaborating nodes and adaptive M-ary quadrature amplitude modulation
(M-QAM)/ M-ary phase shift keying (M-PSK) techniques in generalized wireless fading environments. In
particular, we advocate a simple yet unified numerical approach based on the marginal moment generating
function (MGF) of the total received Signal to Noise Ratio (SNR) to derive analytical expressions for the
average bit error rate (ABER), mean achievable spectral efficiency, and outage probability performance
metrics. The proposed analytical framework is sufficiently general and flexible to characterize the
performance of adaptive-link CAF relay networks over a wide range of fading distributions (i.e., not
restricted to Rayleigh fading or independent identically distributed (i.i.d) Nakagami-m fading ) with
independent but non-identically distributed (i.n.d) fading statistics across the spatially distributed diversity
paths. Additionally, we further simplify the computational complexity, by employing the use of an
“approximate MGF expression” to compute the system performance metrics over the generalized fading
channel. Employing the above novel approach based on “approximate MGF” in conjunction derived
analytical frameworks allows us to simplify the computation complexity of achievable spectral efficiency as
well as ABER of CAF relay system in the generalized fading environments by simply replacing appropriate
single channel MGF which is readily available.
This document discusses optimizing bit loading in broadband power line communication networks. It describes using a greedy bit loading technique to maximize the raw bit rate given available transmission power constraints. The performance of bit loading is analyzed under different system parameters like load conditions, available power, and target error probability. Results show that raw bit rates increase with higher available power and decrease with higher load conditions and lower target error probabilities. Maximum raw bit rates of around 180 Mbps were achieved for the analyzed network model.
O N THE E VALUATION OF G MSK S CHEME W ITH ECC T ECHNIQUES IN W IRELESS S...ijwmn
Wireless sensor nodes are powered by batteries, for
which replacement is very difficult. That is why,
optimization of energy consumption is a major objec
tive in the area of wireless sensor networks (WSNs)
.On
the other hand, noisy channel has a prominent influ
ence on the reliability of data transmission. There
fore,
an energy efficient transmission strategy should be
considered on the communication process of wireles
s
nodes in order to obtain optimal energy network con
sumption. Indeed, the choice of suitable modulation
format with the proper Error Correcting code (ECC)
played a great responsibility to obtain better ener
gy
conservation.In this work, we aim to evaluate the p
erformance analysis of Gaussian Minimum Shift Keyin
g
(GMSK) modulation with several combinations of codi
ng strategies using various analysis metrics such a
s
Bit Error Rate (BER), energy consumption.Through ex
tensive simulation, we disclose that he gain achiev
ed
through GMSK modulation with suitable channel codin
g mechanism is promising to obtain reliable
communication and energy conservation in WSN.
Improvement of crankshaft MAC protocol for wireless sensor networks: a simula...IJECEIAES
Due to the dramatic growth in the use of Wireless Sensor Network (WSN) applications ranging from environment and habitat monitoring to tracking and surveillance, network research in WSN protocols has been very active in the last decade. With battery-powered sensors operating in unattended environments, energy conservation becomes the key technique for improving WSN lifetimes. WSN Medium Access Control (MAC) protocols address energy awareness and reduced duty cycles. The focus of this study is to investigate, through simulation, the effect of variations in various factors that influence the performance results of WSNs. Using MiXiM framework with OMNeT++ simulator, this simulation study proposes modifications in Crankshaft MAC protocol in order to improve its performance. The impact of duration and number of slots, degree of connectivity among the nodes, mobility speed and mobility update interval and also, the impact of sending data packets without preambles are investigated. Based on the simulation results, an improved version of the Crankshaft protocol for WSN is suggested and a comparative study of the performances of the original and improved protocol is presented. The results clearly indicate the superiority of the improved protocol over its original version.
Efficient power allocation method for non orthogonal multiple access 5G systemsIJECEIAES
This document proposes a new power allocation method for non-orthogonal multiple access (NOMA) systems like interleave division multiple access (IDMA). The method uses forward error correction (FEC) code rates to determine the optimal number of users per power level group. Simulation results show that each FEC code can support a limited number (kmax) of equal power users before bit error rate (BER) degrades. The proposed method divides users into groups sized up to but not exceeding kmax. It aims to minimize total transmit power while maintaining a target BER, by finding the minimum required power ratio between groups. Results show the method outperforms conventional techniques with complex computations.
EFFICIENT ANALYSIS OF THE ERGODIC CAPACITY OF COOPERATIVE NON-REGENERATIVE RE...ijwmn
This paper proposes a novel efficient method to analyze the ergodic channel capacity of cooperative amplify-and-forward relay systems. This is accomplished by employing a very tight approximate moment generating function of the end-to-end signal-to-noise ratio that is applicable to various fading environments, including mixed and composite fading channels. Three adaptive source transmission policies are considered: constant power with optimal rate adaptation, optimal joint power and rate adaptation, and fixed rate with truncated channel inversion. Closed-form expressions for ergodic capacity under these policies are derived for Nakagami-m fading with independent but not identically distributed statistics. The accuracy of the proposed approximate method is validated through existing results and Monte Carlo simulations.
EFFICIENT ANALYSIS OF THE ERGODIC CAPACITY OF COOPERATIVE NON-REGENERATIVE RE...ijwmn
In this paper, we proposed a novel efficient method of analyzing the ergodic channel capacity of the
cooperative amplify-and-forward (CAF) relay system. This is accomplished by employing a very tight
approximate moment generating function (MGF) of end-to-end signal-to-noise ratio of 2-hop multi-relay
system, which is In this paper, we proposed a novel efficient method of analyzing the ergodic channel
capacity of the cooperative amplify-and-forward (CAF) relay system. This is accomplished by employing a
very tight approximate moment applicable to myriad of fading environments including mixed and
composite fading channels. Three distinct adaptive source transmission policies were considered in our
analysis namely: (i) constant power with optimal rate adaptation (ORA); (ii) optimal joint power and rate
adaptation (OPRA); and (iii) fixed rate with truncated channel inversion (TCIFR). The proposed frame
work based on the novel approximate MGF method is sufficiently general to encapsulate all types of fading
environments (especially for the analysis of the mixed fading case)and provides significant advantage to
model wireless system for mixed and composite fading channel. In addition to simplifying computation
complexity of ergodic capacity for CAF relaying schemes treated in literature, we also derive closed form
expressions for the above three adaptive source transmission policies under Nakagami-m fading with i.n.d
statistics. The accuracy of our proposed method has been validated with existing MGF expressions that are
readily available for specific fading environments in terms of bounds, and via Monte Carlo simulations.
This document summarizes a research paper that proposes using a hybrid of simulated annealing algorithm and fuzzy rule base system (SA-FRBS) for adaptive coding, modulation, and power allocation in orthogonal frequency-division multiplexing (OFDM) systems. The paper first discusses related work on using evolutionary algorithms like genetic algorithms for adaptive resource allocation in OFDM. It then describes the system model and analyzes the performance of different modulation and coding schemes. Next, it formulates the rate optimization problem and describes the design of the FRBS for selecting the optimal modulation-coding pairs. Finally, it compares the performance of the proposed SA-FRBS approach through simulations.
An approach to control inter cellular interference using load matrix in multi...eSAT Journals
Abstract
This paper deals with reduction of inter cellular interference in Multi-carrier communication systems. In the past, Load Matrix(LM) is proposed to allocate power to different users in a network based upon Signal to noise plus interference ratio (SNIR) so as to reduce inter cellular interference and is observed for single carrier systems. In Multi carrier systems the SNIR is affected distinctly in each carrier thus a single SNIR for power allocation is not optimal. In this paper, to obtain the optimization of power allocation in Multi-Carrier system, Load Matrix coding with bifurcated SNIR (LM-BFSNIR) is proposed. Using this approach it is observed that inter cellular interference is reduced better when compared to a single carrier system evaluated over a 3GPP-LTE standard.
Keywords−Power allocation, Inter cellular interference, Multi-Carrier mobile Communication system.
JOINT-DESIGN OF LINK-ADAPTIVE MODULATION AND CODING WITH ADAPTIVE ARQ FOR COO...IJCNCJournal
This paper analyzes the efficiency of a joint-design of an adaptive modulation and coding (AMC) at the
physical (PHY) layer with an adaptive Rmax-truncated selective-repeat automatic repeat request (ARQ)
protocol at the medium access control (MAC) layer to maximize the throughput of cooperative nonregenerative
relay networks under prescribed delay and/or error performance constraints. Particularly, we
generalize the existing design model/results for cross-layer combining of AMC along with truncated ARQ
in non-cooperative diversity networks in three-folds: (i) extension of the cross-layer PHY/MAC design or
optimization to cooperative diversity systems; (ii) generalization/unification of analytical expressions for
various network performance metrics to generalized block fading channels with independent but nonidentically
distributed (i.n.d) fading statistics among the spatially distributed nodes; (iii) analysis of the
effectiveness of joint-adaptation of the maximum retransmission limit Rmax of ARQ protocol and
cooperative diversity order N for delay-insensitive applications. Our insightful numerical results reveal
that the average throughput can be increased significantly by judiciously combining two additional degrees
of freedom (N and Rmax) that are available in cooperative amplify-and-forward (CAF) relay networks
besides employing AMC at the PHY layer, especially in the most challenging low signal-to-noise ratio
(SNR) regime.
Ieee transactions 2018 topics on wireless communications for final year stude...tsysglobalsolutions
This document contains summaries of several academic papers related to wireless communications and signal processing. The summaries are 3 sentences or less and provide the high level purpose and key findings of each paper. The papers cover topics like content placement in cache-enabled small cell networks, joint beamformer design for wireless fronthaul and access links, long-term power procurement scheduling for smart grids, and frequency-domain compressive channel estimation for hybrid mmWave MIMO systems among others.
Similar to POWER ALLOCATION FOR CAPACITY MAXIMIZATION IN EIGEN-MIMO WITH OUTPUT SNR CONSTRAINT (20)
The Impact of Work Stress and Digital Literacy on Employee Performance at PT ...AJHSSR Journal
ABSTRACT :This research aims to analyze the correlation between employee work stress and digital literacy
with employee performance at PT Telkom Akses Area Cirebon, both concurrently and partially. Employing a
quantitative approach, the study's objectives are descriptive and causal, adopting a positivist paradigm with a
deductive approach to theory development and a survey research strategy. Findings reveal that work stress
negatively and significantly impacts employee performance, while digital literacy positively and significantly
affects it. Simultaneously, work stress and digital literacy have a positive and significant influence on employee
performance. It is anticipated that company management will devise workload management strategies to
alleviate work stress and assess the implementation of more efficient digital technology to enhance employee
performance.
KEYWORDS -digital literacy, employee performance,job stress, multiple regression analysis, workload
management
UR BHatti Academy dedicated to providing the finest IT courses training in the world. Under the guidance of experienced trainer Usman Rasheed Bhatti, we have established ourselves as a professional online training firm offering unparalleled courses in Pakistan. Our academy is a trailblazer in Dijkot, being the first institute to officially provide training to all students at their preferred schedules, led by real-world industry professionals and Google certified staff.
Factors affecting undergraduate students’ motivation at a university in Tra VinhAJHSSR Journal
ABSTRACT: Motivation plays an important role in foreign language learning process. This study aimed to
investigate student’s motivation patterns towards English language learning at a University in Tra Vinh, and factors
affecting their motivation change toward English language learning of non-English-major students in the semester.
The researcher used semi-structured interview at the first phase of choosing the participants and writing reflection
through the instrument called “My English Learning Motivation History” adapted from Sawyer (2007) to collect
qualitative data within 15 weeks. The participants consisted of nine first year non-English-major students who learning
General English at pre-intermediate level. They were chosen and divided into three groups of three members each
(high motivation group; average motivation group; and low motivation group). The results of the present study
identified six visual motivation patterns of three groups of students with different motivation fluctuation, through the
use of cluster analysis. The study also indicated a diversity of factors affecting students’ motivation involving internal
factors as influencing factors (cognitive, psychology, and emotion) and external factors as social factors (instructor,
peers, family, and learning environment) during English language learning in a period of 15 weeks. The findings of
the study helped teacher understand relationship of motivation change and its influential factors. Furthermore, the
findings also inspired next research about motivation development in learning English process.
KEY WORDS: language learning motivation, motivation change, motivation patterns, influential factors, students’
motivation.
STUDY ON THE DEVELOPMENT STRATEGY OF HUZHOU TOURISMAJHSSR Journal
ABSTRACT: Huzhou has rich tourism resources, as early as a considerable development since the reform and
opening up, especially in recent years, Huzhou tourism has ushered in a new period of development
opportunities. At present, Huzhou tourism has become one of the most characteristic tourist cities on the East
China tourism line. With the development of Huzhou City, the tourism industry has been further improved, and
the tourism degree of the whole city has further increased the transformation and upgrading of the tourism
industry. However, the development of tourism in Huzhou City still lags far behind the tourism development of
major cities in East China. This round of research mainly analyzes the current development of tourism in
Huzhou City, on the basis of analyzing the specific situation, pointed out that the current development of
Huzhou tourism problems, and then analyzes these problems one by one, and put forward some specific
solutions, so as to promote the further rapid development of tourism in Huzhou City.
KEYWORDS:Huzhou; Travel; Development
POWER ALLOCATION FOR CAPACITY MAXIMIZATION IN EIGEN-MIMO WITH OUTPUT SNR CONSTRAINT
1. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
DOI : 10.5121/ijitmc.2013.1401 1
POWER ALLOCATION FOR CAPACITY MAXIMIZATION IN
EIGEN-MIMO WITH OUTPUT SNR CONSTRAINT
S. Alireza Banani1
and Dena Homayounieh2
1
Department of Electrical and Computer Engineering, University of Toronto, Toronto,
ON, Canada
2
Faculty of Science and Engineering, York University, Toronto, ON, Canada
ABSTRACT
Water-filling is the power allocation that maximizes the parallel-channel eigen-MIMO information-
theoretic capacity. However, for practical designs, designing for error performance is also important. The
overall uncoded error rate, in a system with water-filled eigen-channels using digital modulation, degrades
through the errors in the data that uses the weaker eigen-channels. This is because in water-filling, a lower
transmit power is allocated (and a lower proportion of the overall capacity) to the weaker eigenchannels.
One general solution is to discard the weaker eigen-channels, but this does still not allow simple control
over the values of, or trade-off between, capacity and the error rate. In this paper a design approach is
presented for the control of, and improvement in, the overall error performance, while maintaining the
ergodic capacity as high as possible. The approach is direct; the eigen-channel power allocation is
optimized for capacity maximization constrained by a desired error performance on the eigenchannels via
constraints on their SNRs. A useful feature is that the capacity and the error performance can be managed
through the eigen-channel SNR constraint. Statistical simulations with Rayleigh channels quantify the
significant SER improvement compared to full eigen-MIMO (maximum number of eigen-channels) with
water-filling, when using a fixed modulation set. This set comprises pre-chosen constellations for a
constant number of eigen-channels, and this remains fixed for the all the channel realizations, i.e., with
time for the time-varying channel. The improvement in error performance is at the expense of a small loss
in capacity.
KEYWORDS
MIMO; water-filling; convex optimization; eigen-channel; ergodic capacity; MIMO capacity
1. INTRODUCTION
Open-loop multiple-input multiple-output (MIMO) systems have the practical advantage of not
requiring channel knowledge at the transmitter. But this practical advantage comes with a
performance penalty because joint optimization between the transmitter and receiver is not fully
deployed. When channel state information (CSI) is available at the transmitter, as assumed in this
paper, MIMO performance can be improved based on a desired optimization criterion such as
capacity, average error rate, etc.
Several jointly optimal linear precoder and decoder (LPD) designs, also called beamformers,
based on perfect channel knowledge at the transmitter, are presented in the literature. These are
too numerous to list here, but representative examples are [1]-[12]. The work in [1] includes the
design that maximizes output SNR, which is called dominant eigenmode transmission. It
2. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
2
transmits only via the strongest eigenchannel, so the power allocation is trivial and the design is
very practical. Water-filled power allocation (i.e., with the total power constrained) for capacity
maximization, is presented in [2] and [3]. For Rayleigh channels, the majority of the available
capacity is available by deploying just one or a few of the available eigenchannels [4]. The
optimal design that minimizes the overall error rate allocates the power on the eigenchannels
according to an inverse water-filling policy [5], [6]. A different approach based on inverse SNR
(or equivalently, mean squared estimation error) between the input and output of each
eigenchannel is studied in [5], [7]. A general solution is a weighted sum of inverse SNRs and
leads to a number of well-known solutions depending on the choice of weights [7]. The optimum
design that maximizes SNR subject to a zero-forcing constraint is also considered in [6]. An
optimal LPD design in [8] is for minimizing the pairwise error probability (PEP) with the total
transmit power constraint. Minimization of the geometric mean square error, defined as the
determinant of the error covariance matrix, is treated in [9]. Capacity maximization with a peak
power constraint is treated in [10].
There are many other specialized schemes (e.g. [11]-[14] with channel estimation and imperfect
feedback), but the basic principles appear in different forms from different disciplines
(information theory, signal processing, communications theory and techniques, adaptive antennas,
etc.). However, there are practical shortcomings with each type of optimized LPD design. For
offering insight into MIMO configurations that are practical but can still maintain high
performance, formulations are required that lie between the limiting capacity, and, for example,
the existing constrained design examples of [1]-[12].
As an example, using water-filling in practice (i.e., with digital modulations), causes the uncoded
error performance to deteriorate with the weakest eigenchannel. Although the weaker eigen-
channels contribute weakly to the overall capacity, the large difference between the average SNR
of the strongest eigenchannel and the average SNR on the lowest eigenchannel can cause
disproportionate error rates across the eigen-channels. In this sense, the overall error rate is
dominated by the weakest eigen-channel. For example, in a 3
3 system with water-filling, the
difference between the average SNR on the strongest eigenchannel and the average SNR on the
lowest eigenchannel is approximately 13.5 dB when the average SNR at each receive antenna is
20 dB. This difference increases to 16.8 dB in a 4
4 system. As a result, full eigen-MIMO
systems with water-filling (i.e. with maximized capacity without an error performance constraint)
have a weak uncoded SER performance which is may not be desirable in practice.
A preferred system has good reliability and high throughput, simultaneously. One solution is to
deploy only the strong eigen-channels, but it is still not straightforward to control the capacity and
SER. Also, the highest possible capacity cannot always be guaranteed for a desired output SER
performance - it is well-known that these quantities trade-off with each other. For the simple
example of a 2
2 MIMO with the fixed modulation set (see below) and a target overall SER of
3
10
, the dominant eigenmode transmission is not the scheme for the highest capacity (seen via
simulation below, for 25 dB SNR).
In this paper, the capacity and reliability (the uncoded SER), are determined together. The method
is to constrain the eigenchannel SNRs for reliability (maximum error rate) and seek a power
allocation over the eigenchannels for the highest capacity. First, an optimization problem is
addressed for maximizing the capacity with the total transmit power constraint and a maximum
allowable SNR reduction (loss of SNR relative to known average SNR at each receiver) imposed
on the eigenchannels - a quantity controlled by the system designer. The optimal power allocation
is obtained via convex optimizations with inequality constraints [16]. The use of convex
optimization itself is not new – it has become a standard tool in MIMO systems design over the
last decade. Then, based on the SNR at each receiver and the maximum allowable SNR loss, the
3. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
3
best power allocation scheme is selected from the presented optimization, water-filling and
dominant eigenmode transmission for the highest capacity. One feature of the approach is that the
position of the capacity between the bounds can be controlled by appropriately setting the
maximum allowable SNR loss.
The simulation results demonstrate an improvement in the SER performance over the case with
water-filling, using a fixed modulation set in a 2
2 MIMO system (a choice of QAM is assigned
to eigenchannel 1 and BPSK to eigenchannel 2). In general, fixed-set modulation has different
constellations assigned to a fixed number of eigenchannels, all the time. Fixed-common
modulation, in which the same constellation is assigned to all the eigenchannels, is a special case
of fixed-set modulation. In other words, unlike adaptive modulation, the modulation over the
ordered eigenchannels does not change for different channel realizations. The advantage of the
fixed-set modulation over adaptive modulation is the reduced complexity in both hardware and
required protocol support. The setting-up of adaptive modulation, particularly in a large multi-
user network, can lead to a large capacity overhead in the system, e.g. [15]. Finally, in discussing
reliability via the error performance of a practical system, the role of data coding is important, but
it is not yet possible to optimize eigen-MIMO with general coding.
The rest of the paper is organized as follows. Section II describes the eigen-MIMO system model.
The problem of capacity maximization with SNR constraint is addressed in section III, with the
simulation results presented in section VI, and section V is the conclusion. The notation is
conventional: vectors are lower case letters and matrices are in bold upper case, with H
, T
and *
meaning conjugate transpose, transpose, and complex conjugate, respectively; I is the
identity matrix; and
E denotes expectation.
2. CLOSED-LOOP MIMO SYSTEM MODEL
Consider a MIMO quasi-static, flat block-fading channel with M transmit and N receive
antennas. The channel is modeled by a random (fading) distribution which remains static over a
fading block cycle, but becomes independent across different blocks. A beamformer W , derived
using channel knowledge at the transmitter, is shown in Fig. 1.
W
x s
Channel : H
v
y
Decoder
Perfect Feedback
Figure 1. An ideal, closed-loop MIMO system with a transmit beamformer for using channel knowledge
which has ideal feedback from the receiver. The ideal feedback link is not part of the capacity calculation
for the forward link.
At each symbol time, the 1
M data vector signal to be transmitted, x, is multiplied by the
M
M weight matrix W , before transmission. With perfect timing, etc., the MIMO system
is modeled in the usual way with notation
v
s
H
v
x
W
H
y
M
M
(1)
4. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
4
where y is the 1
N received signal vector, H is the channel matrix with )
1
,
0
(
~
)
( , CN
j
i
H ,
is the known average SNR at each receive antenna, and v ~ )
1
,
0
(
CN is the additive noise. With
M
H
E I
x
x and x
W
s , the covariance matrix of the transmitted signal is given by
H
H
E WW
s
s
Rss
. From the total average transmit power constraint, W satisfies
M
F
ss
R
W tr
2
, so with x
W
s , we have M
E H
s
s
tr .
3. EIGEN-MIMO CAPACITY MAXIMIZATION
The capacity of a sample realization of the channel is first addressed. The ergodic capacity is the
ensemble average of the capacity achieved when the optimization is performed for each
realization of H , i.e. H
C
E
C . The information theoretic capacity with a fixed channel H is
defined as [3]
H
N
M
E
p M
I
C
H
H
HR
I
y)
;
s ss
ss
s
H
s
det
log
max
(
max 2
tr
)
(
(2)
where )
(s
s
p is the probability density function of the vector s , and )
( y
;
s
I is the mutual
information between s and y .
The matrix H with rank
N
M
r ,
min
can be rewritten as H
V
UΛ
H 2
/
1
where V and U are
the unitary matrices containing the corresponding input and output singular vectors, respectively
and 2
/
1
Λ is a non-negative M
N diagonal matrix with ith diagonal element as
2
/
1
i
(the square
root of ith eigenvalue). In addition the diagonal elements satisfy 1
i
i . As a result,
H
H
V
V
H
H
, and
2
/
1
2
/
1
2
tr
det
log
max VΛ
R
V
Λ
I ss
ss
H
H
N
M
E M
C
H
. (3)
Also, note that V
R
V
R ss
ss
H
~
is non-negative definite, and ss
ss R
R tr
~
tr . Thus, the
maximization over ss
R with M
E H
ss
tr , can be over ss
R
~
with M
E H
s
s~
~
tr . Moreover,
since for any non-negative definite matrix A , i
i
i ,
det A
A
, so
i
i
i
i
N
M
M ,
2
/
1
2
/
1 ~
1
~
det ss
ss R
Λ
R
Λ
I (4)
with the equality for when ss
R
~
is diagonal. Therefore
r
i
i
i
M
E
p
M
C H
1
2
~
~
tr
1
log
max
s
s
H (5)
where i
i
i
p ,
~
ss
R
, and the optimum design corresponds to the SNR on the eigenchannels. The
above results set the scene and are known. The remaining problem is the optimal power allocation
under SNR constraint.
5. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
5
3.1. Optimal Power with SNR Constraint
Here, the r
L
2 strongest eigenchannels are deployed, and their SNRs are constrained as
L
j
SNR SNR
j ,...,
1
;
)
(dB)
(dB)
(
(dB)
(dB)
(6)
where SNR
is the maximum difference between the SNR on the eigenchannels and the average
SNR at each receive antenna, . In other words, the approach guarantees that the SNR loss on
each eigenchannel is smaller than SNR
. Thus, in this optimization problem, there are L
inequality constraints, 10
/
(dB)
10
)
/
(
j
j
p
M , in (6) as well as one equality constraint,
M
pi
. The optimization problem now becomes
M
p
L
j
p
M
p
M
p
p
p
f
L
i i
j
j
L
i
i
i
L
p
p
p L
1
1
2
2
1
0
,
...
,
,
,...,
1
;
)
/
(
to
subject
)
/
(
1
log
)
,...,
,
(
maximize
2
1
(7)
where the objective for the maximization, i.e.,
L
i i
i
p
M
1 2 )
/
(
1
log , is concave in the
variable L
i
pi ,...,
1
; . Equivalently, we can rewrite (7) as
M
p
L
j
p
M
p
p
p
f
p
M
p
p
p
f
L
i i
j
j
L
j
L
i
i
i
L
p
p
p L
1
2
1
1
2
2
1
0
,
...
,
,
,...,
1
;
0
)
/
(
)
,...,
,
(
to
subject
)
/
(
1
log
)
,...,
,
(
minimize
2
1
(8)
where L
f
f
f ...,
,
, 2
1 are convex real functions of L
i
pi ,...,
1
; . In fact, (8) is a convex optimization
problem that includes inequality constraints. A particular interior-point algorithm called the
logarithmic barrier method [16] is used here to solve the problem (8). The first step is to rewrite
(8), making the inequality constraints implicit in the objective
M
p
p
p
p
f
g
p
p
p
f
L
i i
L
j
L
j
L
p
p
p L
1
1
2
1
2
1
0
,
...
,
,
to
subject
))
,...,
,
(
(
)
,...,
,
(
minimize
2
1 (9)
where
:
g is the indicator function for the nonpositive reals,
0
;
0
;
0
)
(
u
u
u
g . (10)
The problem (9) has no inequality constraint, but its objective function is not differentiable, so
descent methods (e.g, Newton’s method, etc.) cannot be applied. The logarithmic barrier method
approximates the indicator function, g , by the function
)
(
log
)
/
1
(
)
(
ˆ 10 u
t
u
g
(11)
6. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
6
where 0
t is a parameter that sets the accuracy of the approximation. Like g , the function ĝ is
convex and nondecreasing, and becomes for 0
u . Unlike g , however, ĝ is differentiable
and increases to as u increases to zero. As t increases, the approximation becomes more
accurate. Substituting ĝ for g in (9) gives
M
p
p
p
p
f
t
p
p
p
f
L
i i
L
j
L
j
L
p
p
p L
1
2
1
1
10
2
1
0
,
...
,
,
to
subject
))
,...,
,
(
(
log
)
/
1
(
)
,...,
,
(
minimize
2
1 (12)
The objective here is convex since )
(
log
)
/
1
( 10 u
t
is convex and increasing in u , and it is
differentiable. The function
L
j L
j
L p
p
p
f
p
p
p 1 2
1
10
2
1 ))
,...,
,
(
(
log
)
,...,
,
( is called the
logarithmic barrier or log barrier for the problem (12). Its domain is the set of points that satisfy
the inequality constraints of (8) strictly. Denoting )
,...,
,
( opt
opt
2
opt
1 L
p
p
p as the solution of (12), it is
shown [16; page 563] that )
,...,
,
( opt
opt
2
opt
1 L
p
p
p is no more than L/t-suboptimal. This suggests a
straightforward method for solving the original problem (8), with a specified accuracy by
taking
/
L
t .
The next step is to solve the equality constraint problem (12), by eliminating the equality
constraint and then solve the resulting unconstrained problem using methods for unconstrained
minimization. 1
p (for example) can be eliminated using the parameterization,
L
i i
p
M
p 2
1 .
The reduced problem is then
L
j
j
j
L
i i
L
i
i
i
L
i i
L
p
p
p
p
M
p
M
M
p
M
p
M
M
t
p
p
p
L
2
10
2
1
10
2
2
2
1
2
3
2
,
...
,
,
)
/
(
log
)
(
)
/
(
log
)
/
(
1
log
)
(
)
/
(
1
log
)
,
...
,
,
(
minimize
3
2
(13)
where the objective is now multiplied by t . Since an affine function of a convex function is also
convex, eliminating equality constraints preserves convexity. Moreover, the elimination of the
equality constraints involves linear algebraic operations. Thus, (13) and (12) are equivalent. Since
)
,
...
,
,
( 3
2 L
p
p
p
is differentiable, a sufficient condition for a point )
,
...
,
,
( opt
opt
3
opt
2 L
p
p
p to be optimal
is
0
)
,
...
,
,
( opt
opt
3
opt
2
L
p
p
p (14)
where )
.
(
denotes the gradient operator. Thus solving the unconstrained minimization
problem (13) is the same as finding a solution of (14), which is a set of 1
L equations in the
1
L variables L
p
p
p ,
...
,
, 3
2 . There is no analytical solution to the optimality problem (14) and so
the problem is solved iteratively, for example using gradient descent:
)
(
)
(
)
1
( n
n
n
p
p (15)
where T
n
L
n
n
n
p
p
p )
(
)
(
3
)
(
2
)
(
p is the solution vector point at nth iteration and
7. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
7
k
k
k
L
j j
k
k
k
L
j j
k
L
k
k
p
M
M
p
M
M
M
p
M
M
p
M
M
M
t
p
)
/
(
)
/
(
)
)(
/
(
)
/
(
)
/
(
1
)
/
(
)
(
)
/
(
1
)
/
(
log
1
2
1
2
1
1
2
10
,...,
2
1
,
1
. (16)
In (15), )
(n
is the step size at iteration n, chosen via a simple inexact line search called a
backtracking line search. In the terminology of iterative methods, the convergence of the gradient
descent algorithm using the backtracking line search is at least linear [16]. The stopping
convergence criteria of an iterative algorithm such as (15) is usually of the form
, where
is small and positive, as suggested by the suboptimality condition [16]. The stopping criterion
is often checked immediately after the descent direction,
, is computed.
The method also requires a suitable starting point )
0
(
p . The objective function in (13) is convex
only on the region that the inequality constraints L
j
p
p
p
f L
j ,...,
1
;
0
)
,...,
,
( 2
1
are satisfied. As
a result the objective function (14) is not convex over the whole work space
M
p
p
M
p
p
p
p
L
j j
j
L
L
S
2
1
1
3
2 ;
0
)
,
...
,
,
( of the iterative algorithm used here. Since
the objective function )
,
...
,
,
( 3
2 L
p
p
p
may have several local minima, the work space S is
divided into D distinct subspaces and the iterative algorithm is run with different starting point
candidates chosen from different subspaces. For example, with uniform gridding of the work
space and splitting the interval for j
p into q equal, distinct segments, we get, at most, 1
L
q
D
subspaces. Then, the converged results are compared to see which one is the global minima.
Denoting )
(c
d
p as the convergent point associated with the starting point chosen from the dth
segment, the optimum point allocation is set as
T
c
T
L p
p
p
p ]
[
]
[ )
(
opt
opt
1
opt
opt
2
opt
1
opt
p
p
(17)
with )
(
min
arg )
(
,...,
1
)
(
opt )
(
c
d
D
d
c
c
d
p
p
p
. (18)
In practice, MIMO systems with 4
N are of immediate interest, and simulations suggest that
for any 4
N , 1
N
q suffices to avoid local convergence using the above procedure. Finally,
we get
L
i i
i
p
M
C 1
opt
2 )
1
(
log
H
and the optimal beamformer opt
W is obtained from
H
WW
Rss and H
V
R
V
R ss
ss
opt
opt ~
as 2
/
1
opt
opt
)
~
ss
R
V(
W .
3.2. Selection from Different Power Allocation Schemes
In general, the presented optimization in (7) does not maximize the ergodic capacity for all values
of system parameters , and SNR
. (this can be seen in the simulations below.) The designer may
choose from different power allocation schemes with the metric of ergodic capacity constrained
by a maximum allowable SNR loss SNR
(in dB). The designer picks SNR
according to the
desired capacity and SER system performances, i.e., capacity and SER are traded off through this
parameter.
8. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
8
The different power allocation schemes for selection are from: the presented optimization; the
water-filling schemes applied to different number of eigenchannels, 2
L ; and the dominant
eigenmode transmission. The selection procedure is as follows. For each value of SNR
, the best
power allocation scheme, along with the best choice for L that achieves the highest capacity, is
selected from the Capacity– SNR
plane. This selection guarantees that the average SNR loss on
each eigenchannel would be smaller than SNR
.
4. SIMULATION RESULTS
To evaluate the performance of the above approach, a 2
2 and a 3
3 MIMO system are
simulated, but the formulation is applicable to any M
N MIMO system. In addition, throughout
the simulations, the theoretical ergodic capacities of water-filled eigen-MIMO and dominant
eigenmode transmission are used as benchmarks.
Figure 2 plots the ergodic capacity (in bits per channel use) versus the SNR loss SNR
(dB) for a
3
3 MIMO system using the presented optimization applied to different number of
eigenchannels, 2
L , with 20
dB. Recall that SNR
is the maximum allowable SNR loss
relative to the average SNR at each receive antenna, imposed on the eigenchannels. It can be
verified that for 2
L , the choice of SNR
that can be set within the presented optimization is
lower bounded by the one obtained with equal SNRs of all eigenchannels, denoted as L
SNR
min
. The
value of L
SNR
min
depends on various system parameters such as )
,
min( N
M
r and L (e.g., for
a 3
3 system, 08
.
6
3
min
L
SNR dB, and 8
.
1
2
min
L
SNR dB whereas in a 2
2 system
96
.
3
2
min
L
SNR dB).
It is worth noting that in water-filling schemes, a fixed reduction of SNR is imposed on each
eigenchannel (this cannot be controlled by the designer) and since the associated SNR loss on the
weakest eigenchannel is the largest loss of all the eigenchannels, it can be set as a lower bound for
the allowable maximum SNR loss in the water-filling scheme. This sets SNR
(dB) for the water
filling case. This is the reason that water-filled capacity curves are the straight lines as seen in
Fig. 2. The same situation also holds for the dominant eigenmode transmission
-2 -1 0 1 2 3 4 5 6 7 8 9 10 11
12.5
13
13.5
14
14.5
15
15.5
16
16.5
17
17.5
SNR loss SNR
(dB)
Ergodic
capacity
(bits
per
channel
use)
water-filling
with three branches
proposed algoirthm
with three branches
water-filling
with two branches
proposed algorithm
with two branches
Figure 2. The ergodic capacity versus the SNR loss SNR
(dB) for a 3
3 MIMO system with 20
dB
9. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
9
(not shown in Fig. 2). The dominant eigenmode transmission has the (fixed) lowest SNR loss of
)
(
log
10 max
10
dom
SNR
; max
max
E , among all schemes.
The capacity results of the presented optimization fall behind the optimal water-filled eigen-
MIMO capacity for the same L . The reason is that, unlike the water-filling scheme that discards
the weakest eigenchannel if the power allocated to it is negative, all of the available L
eigenchannels are used by the presented optimization all the time. It is seen in Fig. 2 that none of
the power allocation schemes maximize the ergodic capacity for all values of , and SNR
. The
designer can choose from a number of power allocation schemes (the presented optimization; the
water-filling schemes applied to different number of eigenchannels, 2
L ; and the dominant
eigenmode transmission) and the metric for selection is the highest ergodic capacity with an
allowable maximum SNR loss SNR
on eigenchannels. For 2
min
dom
L
SNR
SNR
SNR , the dominant
eigenmode transmission is the only candidate for selection (see Fig. 2).
Figures 3 and 4 illustrate the maximum ergodic capacity achieved via selection, constrained with
different choices of SNR
for 30
0
dB in a 3
3 and a 2
2 MIMO systems, respectively.
In general, for larger values of SNR
(larger loss in SNR is allowed), a system with higher
capacity is expected. As a useful feature, the position of the capacity between upper and lower
bounds can be controlled by the designer through the choice of SNR
. Some other interesting
results are: making use of more than one eigenchannel, the capacity curves are upper and
lower bounded by the optimal water-filled capacity using all eigenchannels ( )
,
min( N
M
L ) and
the one obtained via our approach with 2
L and 2
min
L
SNR ; in a 2
2 system, eigenmode
transmission is the best for 6
SNR dB and values of SNR 13
~
dB; and in a 3
3 MIMO
system, it is possible to outperform the water-filled capacity applied to just the two strongest
eigenchannels for any SNR loss 0
SNR dB.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
0
5
10
15
20
25
30
SNR : (dB)
Ergodic
capacity
(bits
per
channel
use)
SNR
= 8 dB
SNR
= 6 dB
min
SNR
= -1.8 dB
SNR
= 10 dB
water-filling
L = 3
dominant eigenmode
transmission
SNR
= 0 - 3 dB
water-filling, L = 2
Figure 3. The maximum ergodic capacity achieved via selection in a 3
3 MIMO system constrained with
different choices of SNR
10. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
10
0 3 6 9 12 15 18 21 24 27 30
2
4
6
8
10
12
14
16
18
SNR (dB)
Ergodic
capacity
(bits
per
channel
use)
dominant eigenmode
transmission
min
SNR
= 3.96 dB
SNR
= 4.5 dB
SNR
= 6 dB
water-filling, L = 2
Figure 4. The maximum ergodic capacity achieved via selection in a 2
2 MIMO system constrained with
different choices of SNR
Simulation results are now presented for a 2
2 MIMO system in which eigenchannel 1 is
deployed with independent QAM and eigenchannel 2 is loaded with BPSK. The overall SER
performance of the system is a measure for comparison among different power allocation
schemes and one definition is
r
i
r
i
i
i
1
1
el
eigenchann
over
symbols
d
transmitte
of
#
el
eigenchann
over
symbols
detected
correctly
of
#
SER (19)
The above formulation allows the number of eigenchannels in the summations to be smaller than
r , and in general, the actual number depends on the type of power allocation scheme used. The
overall SER results for a 2
2 system is illustrated in Fig. 5. Also depicted are the SER curves
associated with each of the eigenchannels when water-filling is used. These reveal how the
overall SER deteriorates with the weakest eigenchannel. In fact, the full eigen-MIMO water-
filling scheme has the worst overall SER performance among other power allocation schemes
and the dominant eigenmode transmission has the best. This is expected because of the trade-off
between the capacity and SER performances.
Because of the selection aspect of the presented approach, the SER curves are piece-wise
discontinuous, and several SER curves for different values of SNR
may lie together for some
SNR regions. For example, in Fig. 5, the curves tagged with dB
6
SNR , dB
5
.
4
SNR , and
dB
96
.
3
SNR lie on the SER result of dominant eigenmode transmission for low to moderate
values of SNR. The promising result is that the overall SER performance is better than that of full
eigen-MIMO water-filling. For example, in a 2
2 system with dB
4
SNR , the improvement
over water-filling is almost 3 dB in SNR for moderate to high values of SNR ( dB
16
~
). This
improvement is at the expense of a loss of 1.9 bits per channel use in capacity compared to that of
water-filling. At low to moderate values of SNR, the advantage is more emphasized – for
SER~10-3,
the equivalent SNR improvement is more than about 15 dB. Here the selection
scheme chooses the dominant eigenmode transmission as the best scheme
11. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
11
0 5 10 15 20 25 30
10
-4
10
-3
10
-2
10
-1
SNR : (dB)
Symbol
error
rate
SNR
= 4.5 dB
dominant eigenmode
transmission
with QPSK
SNR
= 6 dB
SNR
= 3.96 dB
the overall SER
of the MIMO system
using water-filling
SER of eigenchannel 1
with QPSK using
water-filling
SER of eigenchannel 2
with BPSK using water-filling
Figure 5. The overall SER results of a 2
2 system using different power allocation schemes
among others for dB
16
~
and dB
4
SNR and there is only a small loss in capacity (smaller
than 1 bit per channel use for dB
10
~
) relative to that of water-filling.
5. SUMMARY AND CONCLUSIONS
In this paper, the optimal power allocation is formulated for the capacity maximization with the
total input power constraint and a maximum allowable SNR loss on eigenchannels, SNR
. The
goal is to find a way to design an eigen-MIMO system that has good reliability, or error
performance, and high capacity, simultaneously. Comparison of the ergodic capacities from the
presented optimization with that from water-filling with an appropriate number of deployed
eigenchannels, and dominant eigenmode transmission, enable selection for optimal capacity for a
chosen SNR loss, SNR
. One feature of the approach is that the SER performance of the system
and the position of the capacity between the upper and lower bounds can be controlled by the
designer through the choice of SNR
. Promising results are presented for the improvement of SER
performance over than that of full water-filled eigen-MIMO, when using simplified archirectures
such as a fixed-set of modulations or fixed common modulation across the eigen-channels. Here,
a design can have a controllable and significantly better uncoded error performance than full
eigen-MIMO at the expense of a modest loss in capacity. In a practical situation, based on the
type of modulation (and any coding) used, the designer may translate the desirable SNR
performance to a desired SER performance in a system, and then assign SNR
according to the
desired capacity and SER system performances.
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