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.
PACKET SIZE OPTIMIZATION FOR ENERGY EFFICIENCY IN MULTIPATH FADING FOR WIRELE...IJCNCJournal
Recently, Wireless Body Area Network (WBAN) has drawn vast interest to many researchers due to its potential in healthcare and medical fields. In this paper, we propose the energy efficiency model of Time Diversity communication in Rician and Rayleigh fading channels emphasizing the optimal packet size. The optimal packet size to maximize energy efficiency is investigated for on-body and in-body channels. Four modulation techniques are considered including the recently proposed 16-ary Quadrature Amplitude Position Modulation (QAPM). In addition, the closed-form expression of the energy efficiency model in multipath fading is derived. Here, three evaluation metrics including the energy efficiency, the normalized throughput and the average end-to-end delay are adopted and compared to the existing 1-hop and Cooperative communications as well as our previously proposed 2-hop communication. The results show that our proposed Time Diversity communication scheme outperforms the existing ones in deep fading channel except for the average end-to-end delay
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.
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.
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.
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.
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.
PACKET SIZE OPTIMIZATION FOR ENERGY EFFICIENCY IN MULTIPATH FADING FOR WIRELE...IJCNCJournal
Recently, Wireless Body Area Network (WBAN) has drawn vast interest to many researchers due to its potential in healthcare and medical fields. In this paper, we propose the energy efficiency model of Time Diversity communication in Rician and Rayleigh fading channels emphasizing the optimal packet size. The optimal packet size to maximize energy efficiency is investigated for on-body and in-body channels. Four modulation techniques are considered including the recently proposed 16-ary Quadrature Amplitude Position Modulation (QAPM). In addition, the closed-form expression of the energy efficiency model in multipath fading is derived. Here, three evaluation metrics including the energy efficiency, the normalized throughput and the average end-to-end delay are adopted and compared to the existing 1-hop and Cooperative communications as well as our previously proposed 2-hop communication. The results show that our proposed Time Diversity communication scheme outperforms the existing ones in deep fading channel except for the average end-to-end delay
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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 .
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.
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.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
This document summarizes a research paper on hardware efficient reconfigurable FIR filters. It discusses two new architectures proposed: the constant shifts method (CSM) and programmable shifts method (PSM). CSM partitions coefficients into fixed groups and stores them directly in a lookup table. PSM eliminates redundancy in coefficients using a binary common subexpression algorithm before storing in a coded format. Both methods use a shift-and-add unit and multiplexers to efficiently implement coefficient multiplication and allow reconfiguration for different standards. The architectures aim to integrate reconfigurability with low complexity for FIR filters used in wireless communications.
This document proposes a discrete wavelet transform (DWT)-based channel estimation method for MIMO-OFDM systems. It describes the transmitter and receiver structures of a wavelet-based OFDM system with multiple antennas. At the transmitter, data is modulated using inverse DWT and transmitted over frequency-selective channels. At the receiver, received signals are processed using DWT to estimate the channel. Least squares and minimum mean squared error estimation techniques are discussed. Simulation results show the DWT-based system achieves better bit error rate performance than conventional FFT-based OFDM.
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.
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.
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.
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.
Energy efficiency optimization of IEEE 802.15.6 ir uwb wbanaravind m t
The document discusses improving the energy efficiency of cooperative communications in IEEE802.15.6 IR-UWB wireless body area networks (WBANs). It analyzes the use of a one-relay cooperative communication scheme and investigates the impact of hop distance and channel error on energy efficiency through analytical and simulation results. The results show that cooperative communication provides better energy efficiency than direct communication when the source to destination distance is greater than a threshold value and channel conditions are poor.
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.
This document describes a study investigating whether women of grandmother age (35-70 years old) who have previously breastfed children can re-establish milk production through "re-lactation" to potentially prevent mother-to-child HIV transmission in Kenya. The study found that breast milk samples from grandmothers undergoing a 6-week re-lactation intervention contained living cells like those normally present in human breast milk, including macrophages, lymphocytes, epithelial cells, and neutrophils. This suggests that re-lactation may provide a way for grandmothers to feed at-risk infants and reduce pediatric AIDS cases in Kenya, where over 30,000 newborns acquire HIV annually through breastfeeding despite prevention efforts.
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.
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.
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.
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.
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.
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.
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
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 .
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.
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.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
This document summarizes a research paper on hardware efficient reconfigurable FIR filters. It discusses two new architectures proposed: the constant shifts method (CSM) and programmable shifts method (PSM). CSM partitions coefficients into fixed groups and stores them directly in a lookup table. PSM eliminates redundancy in coefficients using a binary common subexpression algorithm before storing in a coded format. Both methods use a shift-and-add unit and multiplexers to efficiently implement coefficient multiplication and allow reconfiguration for different standards. The architectures aim to integrate reconfigurability with low complexity for FIR filters used in wireless communications.
This document proposes a discrete wavelet transform (DWT)-based channel estimation method for MIMO-OFDM systems. It describes the transmitter and receiver structures of a wavelet-based OFDM system with multiple antennas. At the transmitter, data is modulated using inverse DWT and transmitted over frequency-selective channels. At the receiver, received signals are processed using DWT to estimate the channel. Least squares and minimum mean squared error estimation techniques are discussed. Simulation results show the DWT-based system achieves better bit error rate performance than conventional FFT-based OFDM.
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.
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.
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.
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.
Energy efficiency optimization of IEEE 802.15.6 ir uwb wbanaravind m t
The document discusses improving the energy efficiency of cooperative communications in IEEE802.15.6 IR-UWB wireless body area networks (WBANs). It analyzes the use of a one-relay cooperative communication scheme and investigates the impact of hop distance and channel error on energy efficiency through analytical and simulation results. The results show that cooperative communication provides better energy efficiency than direct communication when the source to destination distance is greater than a threshold value and channel conditions are poor.
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.
This document describes a study investigating whether women of grandmother age (35-70 years old) who have previously breastfed children can re-establish milk production through "re-lactation" to potentially prevent mother-to-child HIV transmission in Kenya. The study found that breast milk samples from grandmothers undergoing a 6-week re-lactation intervention contained living cells like those normally present in human breast milk, including macrophages, lymphocytes, epithelial cells, and neutrophils. This suggests that re-lactation may provide a way for grandmothers to feed at-risk infants and reduce pediatric AIDS cases in Kenya, where over 30,000 newborns acquire HIV annually through breastfeeding despite prevention efforts.
Dokumen ini membahas cara membuat form pada program Visual FoxPro. Terdapat beberapa tahapan seperti membuat file project, membuat form kosong, menambahkan label, text box dan tombol, mengatur properti form, menyimpan dan menguji form. Dokumen ini juga memberikan contoh kasus pembbuatan form perhitungan hasil seleksi dan form penjumlahan total barang.
TEX adalah bahasa pemrograman untuk menghasilkan dokumen dengan notasi matematika yang baik, dikembangkan oleh Donald Knuth pada 1977. LaTeX dikembangkan oleh Leslie Lamport berbasis TEX untuk memproduksi dokumen dengan ekstensi .tex, dan banyak digunakan untuk membuat artikel, jurnal, buku. LaTeX versi terbaru adalah LaTeX 2ε yang dirilis 1994. LaTeX membutuhkan editor seperti TeXmaker, TeXworks, Kile untuk menghasilk
Impact of black hole attack on aodv routing protocolZac Darcy
A
m
obile
a
d
-
hoc
n
etwork (MANET)
is a
collection
of wireless mobile nodes
that dynamically self
-
organize
to form an
arbitrary and temporary network.
The mobile nodes can communicate wit
h each other
without
any fixed infrastructure.
MANET
can be set
up quickly to facilitate communication in a hostile environment
such as battlefield or emergency situation.
The various severe security threats are
increasing
on the
MANET
. One of these secur
ity threats is black hole attack which drops all received data packets intended
for forwarding. In this paper, we are simulating and analyzing the impact of black hole attack on Ad Hoc
On
-
Demand Distance Vector (AODV) protocol. Th
e simulation is carried on
NS
-
2 and t
he simulation
results are analyzed
on
various network performance
metric
s such as packet delivery ratio, normalized
routing overhead
and
average end
-
to
-
end delay
The document is divided into sections that contain text blocks including bullet points, frames, and definitions. It introduces topics like scientific pursuit of knowledge, Fermat's Last Theorem, and quotes. The document uses different text structures like headings, bullets, and frames to present information over multiple pages.
Technology, especially IT has affected our lives. Various activities are getting streamlined due to IT. The world today is characterized by powerful IT, forces of collaboration and digitization.
SCM offers tremendous opportunities for researchers. There are both technology led as well as people driven issues which need serious attention from the research community.
Mums are increasingly reliant on their smartphones throughout the purchasing process, with a nearly 100% increase in using smartphones to get product ideas, compare prices, and decide where to buy compared to 2011. The report found that mums are 2.5 times more likely than the general population to check social media on their phones and over half regard their smartphone as an essential parenting tool. Mums also spend more time on social media like Facebook, YouTube, and Tumblr on average compared to the general population.
TEX adalah bahasa pemrograman yang digunakan untuk menghasilkan dokumen dengan notasi matematika yang baik, dikembangkan oleh Donald Knuth pada 1977. LaTeX adalah sistem pengolah dokumen berbasis TEX yang diciptakan oleh Leslie Lamport untuk memproduksi dokumen dengan ekstensi .tex. Terdapat berbagai editor TEX seperti TeXmaker, TeXworks, dan Kile yang digunakan untuk mengedit dan mengkompilasi dokumen LaTeX.
This document provides instructions for real estate agents on how to add testimonials from satisfied customers to their Jumptools website. It explains that testimonials are a quick way for potential clients to learn more about an agent from others' experiences. The steps outlined include logging into Jumptools, editing site content, navigating to the testimonials page, adding new testimonials with client details, and including a testimonial widget on other pages. Customer service contact details are also provided.
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
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
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 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.
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.
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.
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.
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 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.
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.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Similar to Power allocation for capacity maximization in eigen mimo with output snr constraint (20)
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
Further emphasis will be placed on the role of AI in developing XSLT, or schemas such as XSD and Schematron. We will address the techniques and strategies adopted to create prompts for generating code, explaining code, or refactoring the code, and the results achieved.
The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
The presentation aims to deliver a comprehensive overview of AI usage in XML development, providing attendees with the necessary knowledge to make informed decisions. Whether you’re at the early stages of adopting AI or considering integrating it in advanced XML development, this presentation will cover all levels of expertise.
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Letter and Document Automation for Bonterra Impact Management (fka Social Sol...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on automated letter generation for Bonterra Impact Management using Google Workspace or Microsoft 365.
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Nunit vs XUnit vs MSTest Differences Between These Unit Testing Frameworks.pdfflufftailshop
When it comes to unit testing in the .NET ecosystem, developers have a wide range of options available. Among the most popular choices are NUnit, XUnit, and MSTest. These unit testing frameworks provide essential tools and features to help ensure the quality and reliability of code. However, understanding the differences between these frameworks is crucial for selecting the most suitable one for your projects.
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
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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
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 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. 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
DOI : 10.5121/ijitmc.2013.1401
1
2. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
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 eigenchannels 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
103 , 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
2
3. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
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 multiuser 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.
v
x
s
W
y
Channel : H
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 M 1 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
y
H Wx v
Hs v
M
M
(1)
3
4. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
where y is the N 1 received signal vector, H is the channel matrix with (H)i , j ~ CN (0,1) ,
is the known average SNR at each receive antenna, and v ~ CN (0,1) is the additive noise. With
E xx H I M and s Wx , the covariance matrix of the transmitted signal is given by
R ss E s s H WWH . From the total average transmit power constraint,
W
2
F
W
satisfies
tr R ss M , so with s Wx , we have E tr ss H M .
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. C E CH . The information theoretic capacity with a fixed channel H is
defined as [3]
(2)
CH max I (s ; y) max log2 det I N
HRss H H
H
ps ( s )
M
E tr ss M
where ps (s) is the probability density function of the vector s , and I (s ; y ) is the mutual
information between s and y .
The matrix H with rank r minM , N can be rewritten as H UΛ1/ 2 V H where V and U are
the unitary matrices containing the corresponding input and output singular vectors, respectively
and Λ 1/ 2 is a non-negative N M diagonal matrix with ith diagonal element as i
1/ 2
root of ith eigenvalue). In addition the diagonal elements satisfy i i1 .
(the square
As a result,
H H H VV H , and
1/ 2 H
CH max log2 det I N
Λ V R ss VΛ1/ 2 .
H
M
E tr ss M
(3)
~
~
R ss V H R ss V is non-negative definite, and tr R ss tr R ss . Thus, the
~
ss
maximization over R ss with E tr ssH M , can be over R ss with E tr ~ ~ H M . Moreover,
Also, note that
since for any non-negative definite matrix A , det A i A i ,i , so
~
~
det I N Λ1 / 2 R ss Λ 1 / 2 1
R ss
M
M
i
i ,i
i
(4)
~
with the equality for when R ss is diagonal. Therefore
CH max
~~ H
E tr s s M
r
log2 1 M
i 1
pi i
(5)
where p i R ss i ,i , 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.
4
5. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
3.1. Optimal Power with SNR Constraint
Here, the 2 L r strongest eigenchannels are deployed, and their SNRs are constrained as
SNR j (dB) ((dB) SNR (dB) ) ; j 1,..., L
(6)
(dB)
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, ( / M ) p j j 10 (dB) /10 , in (6) as well as one equality constraint,
p i M . The optimization problem now becomes
maximize f 0 ( p1 , p2 ,..., p L ) log2 1 ( / M ) pi i
L
p 1 , p2 , ..., p L
i 1
subject to ( / M ) p j j ; j 1,..., L
(7)
i1 p i M
L
where the objective for the maximization, i.e.,
L
i1 log2 1 ( / M ) pi i , is concave in the
variable p i ; i 1,..., L . Equivalently, we can rewrite (7) as
minimize f 0 ( p1 , p2 ,..., p L ) log2 1 ( / M ) pi i
L
p 1 , p2 , ..., p L
i 1
subject to f j ( p1 , p2 ,..., p L ) ( / M ) p j j 0 ; j 1,..., L
(8)
i 1 p i M
L
where f1 , f 2 ,..., f L are convex real functions of p i ; i 1,..., L . 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
L
minimize f 0 ( p1 , p2 ,..., p L ) g ( f j ( p1 , p2 ,..., p L ))
p 1 , p2 , ..., pL
subject to
j 1
(9)
i1 p i M
L
where g : is the indicator function for the nonpositive reals,
0 ; u 0
.
g (u )
; u 0
(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
ˆ
g (u) (1/ t ) log10 (u)
(11)
5
6. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
ˆ
where t 0 is a parameter that sets the accuracy of the approximation. Like g , the function g is
ˆ
convex and nondecreasing, and becomes for u 0 . Unlike g , however, g is differentiable
and increases to as u increases to zero. As t increases, the approximation becomes more
ˆ
accurate. Substituting g for g in (9) gives
L
minimize f 0 ( p1 , p2 ,..., p L ) (1 / t ) log10 ( f j ( p1 , p2 ,..., p L ))
p 1 , p2 , ..., p L
j 1
subject to
i 1 p i
L
(12)
M
The objective here is convex since (1/ t ) log10 (u) is convex and increasing in u , and it is
differentiable. The function
( p1 , p2 ,..., pL ) j 1 log10 ( f j ( p1 , p2 ,..., pL ))
L
is called the
logarithmic barrier or log barrier for the problem (12). Its domain is the set of points that satisfy
opt
opt
the inequality constraints of (8) strictly. Denoting ( p1opt , p2 ,..., pL ) as the solution of (12), it is
opt
opt
shown [16; page 563] that ( p1opt , p2 ,..., pL ) is no more than L/t-suboptimal. This suggests a
straightforward method for solving the original problem (8), with a specified accuracy by
taking t L / .
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
L
minimization. p 1 (for example) can be eliminated using the parameterization, p 1 M i 2 pi .
The reduced problem is then
minimize ( p 2 , p3 ,..., p L )
p 2 , p3 , ..., p L
L
L
t log 2 1 ( / M ) 1 ( M i 2 pi ) log 2 1 ( / M ) pi i
i 2
(13)
log10 ( / M ) 1 ( M i 2 pi ) log10 ( / M ) p j j
L
L
j 2
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
opt
opt
opt
( p2 , p3 ,..., pL ) is differentiable, a sufficient condition for a point ( p2 , p3 ,..., pL ) to be optimal
is
opt
opt
opt
(14)
( p2 , p3 ,..., pL ) 0
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 L 1 equations in the
L 1 variables p2 , p3 ,..., pL . There is no analytical solution to the optimality problem (14) and so
the problem is solved iteratively, for example using gradient descent:
p ( n1) p ( n ) ( n )
(
where p ( n ) p2n )
(
(
p3n ) pLn )
T
(15)
is the solution vector point at nth iteration and
6
7. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
k 1,1
k 2 ,...,
L
( / M ) 1
( / M ) k
t
L
2
p k
log10 1 ( / M ) 1 ( M j 2 p j ) 1 ( / M ) pk k
( / M ) 1
( / M ) k
L
( / M )(M j 2 p j )1 ( / M ) pk k
.
(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 p ( 0 ) . The objective function in (13) is convex
only on the region that the inequality constraints f j ( p1 , p2 ,..., pL ) 0 ; j 1,...,L are satisfied. As
a result the objective function (14) is not convex over the whole work space
S ( p2 , p3 ,..., pL ) L1 0 p j M ; p1 L 2 p j M of the iterative algorithm used here. Since
j
the objective function ( p2 , p3 ,..., pL ) 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 p j into q equal, distinct segments, we get, at most, D q L1
subspaces. Then, the converged results are compared to see which one is the global minima.
Denoting p (c ) as the convergent point associated with the starting point chosen from the dth
d
segment, the optimum point allocation is set as
opt
opt
c
p opt [ p1opt p2 pL ] T [ p1opt p (opt) ] T
c
p (opt) arg min ( p (dc ) ) .
(c)
with
(17)
(18)
pd
d 1,...,
D
In practice, MIMO systems with N 4 are of immediate interest, and simulations suggest that
for any N 4 , q N 1 suffices to avoid local convergence using the above procedure. Finally,
we get CH iL1 log2 (1
R ss WWH
opt
opt
is obtained
pi i ) and the optimal beamformer W
M
from
~ opt
~ opt
opt
and R ss VR ss V H as Wopt V(R ss ) 1/ 2 .
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.
7
8. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
The different power allocation schemes for selection are from: the presented optimization; the
water-filling schemes applied to different number of eigenchannels, L 2 ; 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 N M 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, L 2 , 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 L 2 , the choice of SNR that can be set within the presented optimization is
min
lower bounded by the one obtained with equal SNRs of all eigenchannels, denoted as SNR
min
value of SNR
L
L 2
. The
depends on various system parameters such as r min(M , N ) and L (e.g., for
min
a 3 3 system, SNR
min
SNR
L
L3
min
6.08 dB, and SNR
L 2
1.8 dB
in a 2 2 system
whereas
3.96 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
Ergodic capacity (bits per channel use)
17.5
water-filling
with three branches
17
16.5
proposed algoirthm
with three branches
16
15.5
15
14.5
14
13.5
water-filling
with two branches
proposed algorithm
with two branches
13
12.5
-2
-1
0
1
2
3
4
5
6
SNR loss SNR (dB)
7
8
9
10
11
Figure 2. The ergodic capacity versus the SNR loss SNR (dB) for a 3 3 MIMO system with 20 dB
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9. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
(not shown in Fig. 2). The dominant eigenmode transmission has the (fixed) lowest SNR loss of
dom 10log10 (max ) ; max E max , among all schemes.
SNR
The capacity results of the presented optimization fall behind the optimal water-filled eigenMIMO 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, L 2 ; 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 dom SNR min L2 , the dominant
SNR
SNR
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 0 30 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 ( L min(M , N ) ) and
min
the one obtained via our approach with L 2 and SNR
L2
; in a 2 2 system,
eigenmode
transmission is the best for SNR 6 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 SNR 0 dB.
Ergodic capacity (bits per channel use)
30
SNR = 8 dB
25
SNR = 6 dB
water-filling
L=3
20
SNR = 10 dB
15
10
SNR = 0 - 3 dB
water-filling, L = 2
5
dominant eigenmode min = -1.8 dB
SNR
transmission
0
0
2
4
6
8
10
12 14 16 18
SNR : (dB)
20
22
24
26
28
30
Figure 3. The maximum ergodic capacity achieved via selection in a 3 3 MIMO system constrained with
different choices of SNR
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10. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
Ergodic capacity (bits per channel use)
18
16
SNR = 4.5 dB
14
SNR = 6 dB
12
10
water-filling, L = 2
8
min = 3.96 dB
SNR
6
dominant eigenmode
transmission
4
2
0
3
6
9
12
15
18
SNR (dB)
21
24
27
30
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
SER
i1 # of correctlydetected symbols over eigenchannel i
r
d
i 1 # of transmitte symbols over eigenchannel i
r
(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 waterfilling 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 SNR 6 dB , SNR 4.5 dB , and
SNR 3.96 dB 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 SNR 4 dB , the improvement
over water-filling is almost 3 dB in SNR for moderate to high values of SNR ( ~ 16 dB ). 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
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11. International Journal of Information Technology, Modeling and Computing (IJITMC) Vol.1,No.4,November 2013
the overall SER
of the MIMO system
using water-filling
-1
10
Symbol error rate
SER of eigenchannel 2
with BPSK using water-filling
SNR = 6 dB
-2
10
SNR = 4.5 dB
dominant eigenmode
transmission
with QPSK
-3
10
-4
10
SNR = 3.96 dB
SER of eigenchannel 1
with QPSK using
water-filling
0
5
10
15
SNR : (dB)
20
25
30
Figure 5. The overall SER results of a 2 2 system using different power allocation schemes
among others for ~ 16 dB and SNR 4 dB and there is only a small loss in capacity (smaller
than 1 bit per channel use for ~ 10 dB ) 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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