This document proposes a short-frame approximation for analyzing the packet loss rate of Irregular Repetition Slotted ALOHA (IRSA), particularly for frames up to 50 slots. The existing approximations become loose for short frames. The proposed approximation, called SF approximation, extends an existing approximation (EF) by considering a larger set of over 20,000 stopping sets, compared to around 60 in the EF approximation. This provides a tighter characterization of packet loss rate for short IRSA frames needed for low-latency IIoT applications. The SF approximation is computed more accurately but is still faster than simulation. Initial results show the SF approximation achieves a 20% lower packet loss rate than the EF approximation for a scenario with 10 slots and
A QUANTITATIVE ANALYSIS OF HANDOVER TIME AT MAC LAYER FOR WIRELESS MOBILE NET...ijwmn
Extensive studies have been carried out for reducing the handover time of wireless mobile network at
medium access control (MAC) layer. However, none of them show the impact of reduced handover time
on the overall performance of wireless mobile networks. This paper presents a quantitative analysis to
show the impact of reduced handover time on the performance of wireless mobile networks. The proposed
quantitative model incorporates many critical performance parameters involve in reducing the handover
time for wireless mobile networks. In addition, we analyze the use of active scanning technique with
comparatively shorter beacon interval time in a handoff process. Our experiments verify that the active
scanning can reduce the overall handover time at MAC layer if comparatively shorter beacon intervals are
utilized for packet transmission. The performance measures adopted in this paper for experimental
verifications are network throughput under different network loads.
A Broadband Wireless Access technology known as
Worldwide Interoperability for Microwave Access (WiMAX) is
based on IEEE 802.16 standards. It uses orthogonal frequency
division multiple accesses (OFDMA) as one of its multiple access
technique. Major design factors of OFDMA resource allocation are
scheduling and burst allocation. To calculate the appropriate
dimensions and location of each user’s data so as to construct the
bursts in the downlink subframe, is the responsibility of burst
allocation algorithm. Bursts are calculated in terms of number of
slots for each user. Burst Allocation Algorithm is used to overcome
the resource wastage in the form of unused and unallocated slots per
frame. It affects the Base station performance in mobile WiMAX
systems. In this Paper, HOCSA (Hybrid One Column Striping with
Non Increasing Area) algorithm is proposed to overcome frame
wastage. HOCSA is implemented by improving eOCSA algorithm
and is evaluated using MATLAB. HOCSA achieves significant
reduction of resource wastage per frame, leading to more
exploitation of the WiMAX frame.
IRJET- Performance Analysis of a Synchronized Receiver over Noiseless and Fad...IRJET Journal
This document summarizes the performance analysis of a synchronized receiver over noiseless and fading channels. It presents a baseband communications system that implements data phase transmission using a single-tone waveform. The behavior of the received signal when transmitted over a noiseless channel and a fading frequency selective channel with additive white Gaussian noise is analyzed. Key plots analyzed include the channel output power spectrum, cross-spectral phase between the equalizer input and output, control signal for the equalizer, and scatter plots of the equalizer input, output, and descrambler output. The analysis shows distortion of the signal due to noise in the fading channel.
A Novel Carrier Indexing Method for Side Lobe Suppression and Bit Error Rate ...IRJET Journal
This paper proposes a novel carrier indexing method using variable basis functions to suppress side lobes and reduce bit error rates in non-continuous OFDM (NC-OFDM) systems. Existing active interference cancellation techniques used fixed-length rectangular basis functions for cancellation carriers, which were not optimal. The proposed method groups cancellation carriers by frequency position and shapes them with variable-length waveforms to more effectively suppress NC-OFDM side lobes while reducing inter-carrier interference. Simulation results show the proposed approach achieves over 80dB side lobe reduction and negligible inter-carrier interference compared to existing techniques. The method provides reliable data transmission between primary and secondary nodes in cognitive radio networks with lower bit error rates.
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.
This document proposes two low power flexible Rake receiver architectures for WCDMA systems. The first architecture reduces power by avoiding writing redundant samples to the SRAM buffer based on the statistical distribution of multipath delays. The second architecture eliminates the SRAM buffer altogether by selecting the appropriate phase of the decoding code for each multipath, trading off memory access for increased code generator switching. Both architectures aim to significantly reduce area and power compared to previous flexible Rake receivers while maintaining performance.
Low-Complexity DFT-Based Channel Estimation with Leakage Nulling for OFDM Sys...john236zaq
This document summarizes a research paper that proposes a low-complexity channel estimation method for OFDM systems using virtual subcarriers. The proposed method uses a time-domain index set estimation considering leakage effects followed by a low-complexity time-domain post-processing to suppress leakage. Simulation results show the proposed estimator achieves near-optimal performance while maintaining low complexity comparable to simple DFT-based estimators.
Efficient Broadcast Authentication with Highest Life Span in Wireless Sensor ...IRJET Journal
This document discusses efficient broadcast authentication to maximize the lifetime of wireless sensor networks. It proposes using a greedy heuristics algorithm with the X-TESLA broadcast authentication protocol. X-TESLA uses short key chains to authenticate broadcast messages but has limitations regarding sleep modes, network failures, idle sessions, extended lifetime, and denial-of-service attacks. The proposed approach combines X-TESLA with greedy heuristics to address these issues and significantly improve network lifetime compared to using each approach alone. It aims to find a broadcast tree that maximizes the minimum residual energy of nodes after broadcasting to prolong the ability of the network to complete future broadcasts.
A QUANTITATIVE ANALYSIS OF HANDOVER TIME AT MAC LAYER FOR WIRELESS MOBILE NET...ijwmn
Extensive studies have been carried out for reducing the handover time of wireless mobile network at
medium access control (MAC) layer. However, none of them show the impact of reduced handover time
on the overall performance of wireless mobile networks. This paper presents a quantitative analysis to
show the impact of reduced handover time on the performance of wireless mobile networks. The proposed
quantitative model incorporates many critical performance parameters involve in reducing the handover
time for wireless mobile networks. In addition, we analyze the use of active scanning technique with
comparatively shorter beacon interval time in a handoff process. Our experiments verify that the active
scanning can reduce the overall handover time at MAC layer if comparatively shorter beacon intervals are
utilized for packet transmission. The performance measures adopted in this paper for experimental
verifications are network throughput under different network loads.
A Broadband Wireless Access technology known as
Worldwide Interoperability for Microwave Access (WiMAX) is
based on IEEE 802.16 standards. It uses orthogonal frequency
division multiple accesses (OFDMA) as one of its multiple access
technique. Major design factors of OFDMA resource allocation are
scheduling and burst allocation. To calculate the appropriate
dimensions and location of each user’s data so as to construct the
bursts in the downlink subframe, is the responsibility of burst
allocation algorithm. Bursts are calculated in terms of number of
slots for each user. Burst Allocation Algorithm is used to overcome
the resource wastage in the form of unused and unallocated slots per
frame. It affects the Base station performance in mobile WiMAX
systems. In this Paper, HOCSA (Hybrid One Column Striping with
Non Increasing Area) algorithm is proposed to overcome frame
wastage. HOCSA is implemented by improving eOCSA algorithm
and is evaluated using MATLAB. HOCSA achieves significant
reduction of resource wastage per frame, leading to more
exploitation of the WiMAX frame.
IRJET- Performance Analysis of a Synchronized Receiver over Noiseless and Fad...IRJET Journal
This document summarizes the performance analysis of a synchronized receiver over noiseless and fading channels. It presents a baseband communications system that implements data phase transmission using a single-tone waveform. The behavior of the received signal when transmitted over a noiseless channel and a fading frequency selective channel with additive white Gaussian noise is analyzed. Key plots analyzed include the channel output power spectrum, cross-spectral phase between the equalizer input and output, control signal for the equalizer, and scatter plots of the equalizer input, output, and descrambler output. The analysis shows distortion of the signal due to noise in the fading channel.
A Novel Carrier Indexing Method for Side Lobe Suppression and Bit Error Rate ...IRJET Journal
This paper proposes a novel carrier indexing method using variable basis functions to suppress side lobes and reduce bit error rates in non-continuous OFDM (NC-OFDM) systems. Existing active interference cancellation techniques used fixed-length rectangular basis functions for cancellation carriers, which were not optimal. The proposed method groups cancellation carriers by frequency position and shapes them with variable-length waveforms to more effectively suppress NC-OFDM side lobes while reducing inter-carrier interference. Simulation results show the proposed approach achieves over 80dB side lobe reduction and negligible inter-carrier interference compared to existing techniques. The method provides reliable data transmission between primary and secondary nodes in cognitive radio networks with lower bit error rates.
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.
This document proposes two low power flexible Rake receiver architectures for WCDMA systems. The first architecture reduces power by avoiding writing redundant samples to the SRAM buffer based on the statistical distribution of multipath delays. The second architecture eliminates the SRAM buffer altogether by selecting the appropriate phase of the decoding code for each multipath, trading off memory access for increased code generator switching. Both architectures aim to significantly reduce area and power compared to previous flexible Rake receivers while maintaining performance.
Low-Complexity DFT-Based Channel Estimation with Leakage Nulling for OFDM Sys...john236zaq
This document summarizes a research paper that proposes a low-complexity channel estimation method for OFDM systems using virtual subcarriers. The proposed method uses a time-domain index set estimation considering leakage effects followed by a low-complexity time-domain post-processing to suppress leakage. Simulation results show the proposed estimator achieves near-optimal performance while maintaining low complexity comparable to simple DFT-based estimators.
Efficient Broadcast Authentication with Highest Life Span in Wireless Sensor ...IRJET Journal
This document discusses efficient broadcast authentication to maximize the lifetime of wireless sensor networks. It proposes using a greedy heuristics algorithm with the X-TESLA broadcast authentication protocol. X-TESLA uses short key chains to authenticate broadcast messages but has limitations regarding sleep modes, network failures, idle sessions, extended lifetime, and denial-of-service attacks. The proposed approach combines X-TESLA with greedy heuristics to address these issues and significantly improve network lifetime compared to using each approach alone. It aims to find a broadcast tree that maximizes the minimum residual energy of nodes after broadcasting to prolong the ability of the network to complete future broadcasts.
The document compares the performance of a Root Raised Cosine matched filter implemented using hybrid-logarithmic arithmetic versus standard binary and floating point arithmetic. Simulations showed that the hybrid logarithmic structure offered superior performance to fixed point solutions while having significantly reduced complexity compared to floating point equivalents. The use of hybrid logarithmic arithmetic also has the potential to reduce power consumption, latency, and hardware complexity for mobile applications.
The improvement of end to end delays in network management system using netwo...IJCNCJournal
The document summarizes research on improving end-to-end delays in a network management system using network coding. Specifically, it applies network coding to manage radio and television broadcast stations in a wireless network. The study shows that a proposed "Fast Forwarding Strategy" using network coding outperforms a classical routing strategy in reducing end-to-end delays from source to destination. It analyzes end-to-end delays theoretically using network calculus and conducts a practical study on a network of broadcast stations, finding the proposed strategy reduces delays compared to the classical strategy.
Efficient FPGA implementation of high speed digital delay for wideband beamfor...journalBEEI
In this paper, the authors present an FPGA implementation of a digital delay for beamforming applications. The digital delay is based on a Parallel Farrow Filter. Such architecture allows to reach a very high processing rate with wideband signals and it is suitable to be used with Time-Interleaved Analog to Digital Converters (TI-ADC). The proposed delay has been simulated in MATLAB, implemented on FPGA and characterized in terms of amplitude and phase response, maximum clock frequency and area.
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.
Scheduling and Resource allocation in 802.11ax (WIFI 6)RESHAN FARAZ
--> IIITD Course Project.
--> Implementation of Scheduling and Resource allocation in 802.11ax using NS-3.
-->Modified Largest Weighted Delay First.
--> Comparison of Round Robin Scheduling with Modified Largest Weighted Delay First.
-->Source Code:-https://github.com/reshan9b11/MLWDF_WN_PROJECT
IRJET- Performance Improvement for Distance Relay based Fuzzy Logic for All P...IRJET Journal
1) The document describes a study that uses an adaptive neuro-fuzzy inference system (ANFIS) algorithm to design a three-phase distance relay with fuzzy logic for fault detection and classification in overhead transmission lines.
2) The ANFIS generates a fuzzy system with two parts - the first detects faults by measuring voltage and current to calculate impedance, while the second determines fault location and type based on peak current values.
3) Simulation results showed the fuzzy logic distance relay successfully distinguished faults from disturbances, determined protection zones, and identified fault locations and types using data from a model of a 400kV transmission line in MATLAB/Simulink.
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.
Analysis of data transmission in wireless lan for 802.11 e2 eteSAT Journals
Abstract The aim of this paper is to investigate the transmission of data between client and server through different IEEE 802.11 wireless LAN multi- HOP network. To improve this issue, the transmission opportunity (TXOP) mechanism is defined in the IEEE 802.11e standard, with which a wireless node can transmit multiple frames consecutively for a maximum channel occupancy time, called TXOP limit. This paper considers the performance of the TXOP mechanism for multi-hop wireless networks. Focusing on a three-node chain topology, we model it as a tandem queuing network with two nodes. The E2ET is derived and the analysis is validated by simulation. Numerical results show that the TXOP mechanism works well for multi-hop wireless networks. It is also shown that adjusting TXOP limit is significantly important in order to increase the overall throughput. In terms of multi-hop wireless networks, there is little analytical work with regard to the E2ET performance. One of the rationales for the analytical difficulty for multi-hop wireless networks is that IEEE 802.11 MAC protocol is too complex to model the behavior of multi-hop frame transmissions. Keywords: IEEE 802.11e, multi-hop wireless LAN, TXOP, E2ET
COMPARATIVE ANALYSIS OF SIMULATION TECHNIQUES: SCAN COMPRESSION AND INTERNAL ...IJCI JOURNAL
This document compares two design for testability (DFT) pattern simulation techniques: scan compression and internal scan. Scan compression divides long scan chains into shorter chains using a compressor and decompressor, reducing simulation time significantly with little area overhead. An experiment on benchmark circuits found scan compression detects more faults, achieves higher coverage, and reduces simulation time by up to 99.7% compared to internal scan, though it increases area by 10-20%. In conclusion, scan compression is more time efficient than internal scan for testing large designs.
Hybrid ldpc and stbc algorithms to improve ber reduction in ofdmIAEME Publication
This document discusses improving bit error rate (BER) performance in orthogonal frequency division multiplexing (OFDM) systems using hybrid low-density parity check (LDPC) codes and space-time block coding (STBC). It first describes MMSE and LS channel estimation techniques in OFDM and an adaptive modulation and coding WiMAX system. It then proposes using LDPC codes with STBC across multiple transmit antennas to achieve coding gain and diversity gain. Simulation results show the hybrid LDPC-STBC method provides better BER performance than STBC alone, especially at low signal-to-noise ratios in flat Rayleigh fading channels.
Due to advances in smart grid, different communication links as delay, intertrip and activation are used between relays to enhance the protection system performance. In this paper, the effect of inter-trip links on optimal coordination of directional overcurrent relays (DOCRs) is analytically investigated and modelled. Moreover, an index is proposed to find the optimum locations for inter-trip link installation to reach the minimal fault clearance times under the selectivity constraint. Then a method is proposed to determine the candidate locations of inter-trip links and the associated reduced operating times. An Exhaustive search approach is also used to validate the efficiency of the proposed method. The method is simulated and tested on distribution network of IEEE 33 bus using the Power Factory software and MATLAB optimization toolbox. Genetic algorithm is used as an optimization tool to find optimal settings of relays. The results indicate the capability of proposed method in optimal protection coordination with optimum inter-trips.
1) The planning of Physical Cell Identities (PCI) has a strong impact on the performance of LTE networks. PCI planning determines the frequency locations of cell-specific reference signals, which can collide between neighboring cells and degrade signal quality estimates.
2) Most research on PCI planning has focused on avoiding collisions and confusion between PCI assignments. However, no study has quantified the impact of PCI planning on downlink throughput performance.
3) This paper develops an analytical model to quantify the influence of PCI planning on reference signal collisions. It then uses a system-level simulator to test different PCI planning schemes and analyze their impact on call blocking, dropping, and user throughput under various traffic conditions.
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
An efficient ant optimized multipath routing in wireless sensor networkEditor Jacotech
Today, the Wireless Sensor Network is increasingly gaining popularity and importance. It is the more interesting and stimulating area of research. Now, the WSN is applied in object tracking and environmental monitoring applications. This paper presents the self-optimized model of multipath routing algorithm for WSN which considers definite parameters like delay, throughput level and loss and generates the outcomes that maximizes data throughput rate and minimizes delay and loss. This algorithm is based on ANT optimization technique that will bring out an optimal and organized route for WSN and is also to avoid congestion in WSN, the algorithm incorporate multipath capability..
Ieee transactions 2018 on wireless communications Title and Abstracttsysglobalsolutions
Final year BE, B.Tech, ME, M.Tech projects along with our professionals for developing Real Time Applications in Emerging Technologies.
We can support to your final year projects in all domains with latest technologies and simulation tool like NS2, NS3, Glomosim, Opnet, Matlab, IDL, Sumo, Gridsim, Bonita tool & Cloud deployments (Cloudsim, Google App Engine, Amazon Deployment, and Real time Cloud Deployment)also we are support for JOURNAL and CONFERENCE Preparation.
?
TSYS Research and Development.
20/9 Sardar Patel Road, Janaki Complex,
4th Floor, Adyar, Chennai - 20?
Tel : 91 44 42607879, 98411 03123.
Website : http://www.tsysglobalsolutions.com/
http://tsysphdsupport.com/
PERFORMANCE ANALYSIS OF RESOURCE SCHEDULING IN LTE FEMTOCELLS NETWORKScscpconf
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and time dimension. So several scheduling algorithms need to be analyzed for femtocells networks. In this paper we introduce a performance analysis of three distinct scheduling algorithms of mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in terms of throughput, packet loss ratio, fairness index and spectral efficiency.
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize
the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and
time dimension. So several scheduling algorithms need to be analyzed for femtocells networks.
In this paper we introduce a performance analysis of three distinct scheduling algorithms of
mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in
terms of throughput, packet loss ratio, fairness index and spectral efficiency.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
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.
This document discusses and compares the performance of four blind adaptive multiuser detection algorithms: LMS, RLS, Kalman filter, and subspace-based Kalman filter. It provides background on blind multiuser detection and describes each algorithm's approach. The subspace-based Kalman filter algorithm models the detector as a vector in the signal subspace and employs a Kalman filter to adaptively estimate the coefficients. Simulation results showed that the subspace-based Kalman filter algorithm outperformed the other three algorithms in terms of faster convergence speed and capability to increase the capacity of CDMA systems.
MASSIVE MACHINE TYPE COMMUNICATION TOWARDS 6G.pdfYAAKOVSOLOMON1
This white paper explores key research directions for machine type communication (MTC) towards 6G networks by 2030. It discusses the main societal drivers of MTC, such as autonomous mobility and smart manufacturing. Representative MTC use cases are presented across various industries. Emerging MTC services are expected to have highly diverse requirements in terms of performance metrics like reliability, latency, energy efficiency, and scalability. The white paper investigates potential enabling technologies for building a holistic MTC network architecture in 6G that can efficiently support both massive and critical MTC services.
The document compares the performance of a Root Raised Cosine matched filter implemented using hybrid-logarithmic arithmetic versus standard binary and floating point arithmetic. Simulations showed that the hybrid logarithmic structure offered superior performance to fixed point solutions while having significantly reduced complexity compared to floating point equivalents. The use of hybrid logarithmic arithmetic also has the potential to reduce power consumption, latency, and hardware complexity for mobile applications.
The improvement of end to end delays in network management system using netwo...IJCNCJournal
The document summarizes research on improving end-to-end delays in a network management system using network coding. Specifically, it applies network coding to manage radio and television broadcast stations in a wireless network. The study shows that a proposed "Fast Forwarding Strategy" using network coding outperforms a classical routing strategy in reducing end-to-end delays from source to destination. It analyzes end-to-end delays theoretically using network calculus and conducts a practical study on a network of broadcast stations, finding the proposed strategy reduces delays compared to the classical strategy.
Efficient FPGA implementation of high speed digital delay for wideband beamfor...journalBEEI
In this paper, the authors present an FPGA implementation of a digital delay for beamforming applications. The digital delay is based on a Parallel Farrow Filter. Such architecture allows to reach a very high processing rate with wideband signals and it is suitable to be used with Time-Interleaved Analog to Digital Converters (TI-ADC). The proposed delay has been simulated in MATLAB, implemented on FPGA and characterized in terms of amplitude and phase response, maximum clock frequency and area.
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.
Scheduling and Resource allocation in 802.11ax (WIFI 6)RESHAN FARAZ
--> IIITD Course Project.
--> Implementation of Scheduling and Resource allocation in 802.11ax using NS-3.
-->Modified Largest Weighted Delay First.
--> Comparison of Round Robin Scheduling with Modified Largest Weighted Delay First.
-->Source Code:-https://github.com/reshan9b11/MLWDF_WN_PROJECT
IRJET- Performance Improvement for Distance Relay based Fuzzy Logic for All P...IRJET Journal
1) The document describes a study that uses an adaptive neuro-fuzzy inference system (ANFIS) algorithm to design a three-phase distance relay with fuzzy logic for fault detection and classification in overhead transmission lines.
2) The ANFIS generates a fuzzy system with two parts - the first detects faults by measuring voltage and current to calculate impedance, while the second determines fault location and type based on peak current values.
3) Simulation results showed the fuzzy logic distance relay successfully distinguished faults from disturbances, determined protection zones, and identified fault locations and types using data from a model of a 400kV transmission line in MATLAB/Simulink.
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.
Analysis of data transmission in wireless lan for 802.11 e2 eteSAT Journals
Abstract The aim of this paper is to investigate the transmission of data between client and server through different IEEE 802.11 wireless LAN multi- HOP network. To improve this issue, the transmission opportunity (TXOP) mechanism is defined in the IEEE 802.11e standard, with which a wireless node can transmit multiple frames consecutively for a maximum channel occupancy time, called TXOP limit. This paper considers the performance of the TXOP mechanism for multi-hop wireless networks. Focusing on a three-node chain topology, we model it as a tandem queuing network with two nodes. The E2ET is derived and the analysis is validated by simulation. Numerical results show that the TXOP mechanism works well for multi-hop wireless networks. It is also shown that adjusting TXOP limit is significantly important in order to increase the overall throughput. In terms of multi-hop wireless networks, there is little analytical work with regard to the E2ET performance. One of the rationales for the analytical difficulty for multi-hop wireless networks is that IEEE 802.11 MAC protocol is too complex to model the behavior of multi-hop frame transmissions. Keywords: IEEE 802.11e, multi-hop wireless LAN, TXOP, E2ET
COMPARATIVE ANALYSIS OF SIMULATION TECHNIQUES: SCAN COMPRESSION AND INTERNAL ...IJCI JOURNAL
This document compares two design for testability (DFT) pattern simulation techniques: scan compression and internal scan. Scan compression divides long scan chains into shorter chains using a compressor and decompressor, reducing simulation time significantly with little area overhead. An experiment on benchmark circuits found scan compression detects more faults, achieves higher coverage, and reduces simulation time by up to 99.7% compared to internal scan, though it increases area by 10-20%. In conclusion, scan compression is more time efficient than internal scan for testing large designs.
Hybrid ldpc and stbc algorithms to improve ber reduction in ofdmIAEME Publication
This document discusses improving bit error rate (BER) performance in orthogonal frequency division multiplexing (OFDM) systems using hybrid low-density parity check (LDPC) codes and space-time block coding (STBC). It first describes MMSE and LS channel estimation techniques in OFDM and an adaptive modulation and coding WiMAX system. It then proposes using LDPC codes with STBC across multiple transmit antennas to achieve coding gain and diversity gain. Simulation results show the hybrid LDPC-STBC method provides better BER performance than STBC alone, especially at low signal-to-noise ratios in flat Rayleigh fading channels.
Due to advances in smart grid, different communication links as delay, intertrip and activation are used between relays to enhance the protection system performance. In this paper, the effect of inter-trip links on optimal coordination of directional overcurrent relays (DOCRs) is analytically investigated and modelled. Moreover, an index is proposed to find the optimum locations for inter-trip link installation to reach the minimal fault clearance times under the selectivity constraint. Then a method is proposed to determine the candidate locations of inter-trip links and the associated reduced operating times. An Exhaustive search approach is also used to validate the efficiency of the proposed method. The method is simulated and tested on distribution network of IEEE 33 bus using the Power Factory software and MATLAB optimization toolbox. Genetic algorithm is used as an optimization tool to find optimal settings of relays. The results indicate the capability of proposed method in optimal protection coordination with optimum inter-trips.
1) The planning of Physical Cell Identities (PCI) has a strong impact on the performance of LTE networks. PCI planning determines the frequency locations of cell-specific reference signals, which can collide between neighboring cells and degrade signal quality estimates.
2) Most research on PCI planning has focused on avoiding collisions and confusion between PCI assignments. However, no study has quantified the impact of PCI planning on downlink throughput performance.
3) This paper develops an analytical model to quantify the influence of PCI planning on reference signal collisions. It then uses a system-level simulator to test different PCI planning schemes and analyze their impact on call blocking, dropping, and user throughput under various traffic conditions.
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
An efficient ant optimized multipath routing in wireless sensor networkEditor Jacotech
Today, the Wireless Sensor Network is increasingly gaining popularity and importance. It is the more interesting and stimulating area of research. Now, the WSN is applied in object tracking and environmental monitoring applications. This paper presents the self-optimized model of multipath routing algorithm for WSN which considers definite parameters like delay, throughput level and loss and generates the outcomes that maximizes data throughput rate and minimizes delay and loss. This algorithm is based on ANT optimization technique that will bring out an optimal and organized route for WSN and is also to avoid congestion in WSN, the algorithm incorporate multipath capability..
Ieee transactions 2018 on wireless communications Title and Abstracttsysglobalsolutions
Final year BE, B.Tech, ME, M.Tech projects along with our professionals for developing Real Time Applications in Emerging Technologies.
We can support to your final year projects in all domains with latest technologies and simulation tool like NS2, NS3, Glomosim, Opnet, Matlab, IDL, Sumo, Gridsim, Bonita tool & Cloud deployments (Cloudsim, Google App Engine, Amazon Deployment, and Real time Cloud Deployment)also we are support for JOURNAL and CONFERENCE Preparation.
?
TSYS Research and Development.
20/9 Sardar Patel Road, Janaki Complex,
4th Floor, Adyar, Chennai - 20?
Tel : 91 44 42607879, 98411 03123.
Website : http://www.tsysglobalsolutions.com/
http://tsysphdsupport.com/
PERFORMANCE ANALYSIS OF RESOURCE SCHEDULING IN LTE FEMTOCELLS NETWORKScscpconf
3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
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3GPP has introduced LTE Femtocells to manipulate the traffic for indoor users and to minimize
the charge on the Macro cells. A key mechanism in the LTE traffic handling is the packet
scheduler which is in charge of allocating resources to active flows in both the frequency and
time dimension. So several scheduling algorithms need to be analyzed for femtocells networks.
In this paper we introduce a performance analysis of three distinct scheduling algorithms of
mixed type of traffic flows in LTE femtocells networks. The particularly study is evaluated in
terms of throughput, packet loss ratio, fairness index and spectral efficiency.
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### How TDM Works
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### Types of TDM
1. **Synchronous TDM**: In synchronous TDM, time slots are pre-assigned to each signal, regardless of whether the signal has data to transmit or not. This can lead to inefficiencies if some time slots remain empty due to the absence of data.
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### Applications of TDM
- **Telecommunications**: TDM is extensively used in telecommunication systems, such as in T1 and E1 lines, where multiple telephone calls are transmitted over a single line by assigning each call to a specific time slot.
- **Digital Audio and Video Broadcasting**: TDM is used in broadcasting systems to transmit multiple audio or video streams over a single channel, ensuring efficient use of bandwidth.
- **Computer Networks**: TDM is used in network protocols and systems to manage the transmission of data from multiple sources over a single network medium.
### Advantages of TDM
- **Efficient Use of Bandwidth**: TDM all
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2. 2
avoided with grant-free access protocols. Currently deployed grant-free algorithms solve the
reliability problem with over-provisioning in the 5G New Radio (NR) [3]. Modern random
access algorithms instead avoid over-provisioning through the use of Interference Cancellation
(IC) [4]. A recent work [5] has discussed their adaptation to 5G without reliability guarantees.
Irregular Repetition Slotted ALOHA (IRSA) is one popular modern random access algorithm.
It can reach a normalized throughput of 0.97 packets/slot [6] for very large frames and 0.8
with 1000 slots. However, achieving low latency requires short IRSA frames, i.e. 10 to 50 slots.
In this regime the asymptotic analysis of [6] becomes loose, and different strategies to model
the performance shall be followed. Note that a precise characterization of the packet loss rate
(PLR) in IRSA for finite frames, given certain number of users, is needed to provide reliability
guarantees.
Approximations of the PLR for both the waterfall [7] and error floor [1] regimes can be
found in the literature.1 While the former follows well the PLR for medium to high channel
load values, the latter is meant for regions of low traffic load. Fig. 1 shows the packet loss rate
results of a simulation with an IRSA frame of 10 slots together with both approximations, as
a function of the channel load, i.e. the average number of users accessing per time slot. As an
example of the IRSA access policy, we considered a scenario where three physical layer copies
of the same packet are transmitted. As one can observe, the waterfall approximation has a good
match for channel loads above 0.8. Nonetheless, the packet loss rate in this region is well above
0.5 (i.e. more than half of the packets cannot be correctly received), an unacceptable operating
point for IIoT applications. Specifically, low PLR is one of the main requirements of IIoT, so
the waterfall region is not further investigated in this work.
In the error floor regime, the EF approximation [1] can be adopted to predict the performance
of the PLR. However, as clearly depicted in Fig. 1, the EF approximation rapidly diverges from
the simulation already for rather small load values and does not provide a good prediction. It
is evident that a tighter PLR approximation is needed for analyzing the performance of IRSA
under very stringent latency requirements, enabling IIoT applications to benefit from such access
policy.
Our contribution can be summarized as follows: we extend the EF approximation of [1]
1Another approximation of the PLR for IRSA can be found in [8]. Although being an interesting alternative, the results
provided by the author appear to be less attractive compared to [1] in terms of tightness.
3. 3
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
10−2
10−1
100
load G
packet
loss
rate
p
l
simulation
waterfall [7]
EF [1]
SF
Fig. 1. An IRSA scenario with 10 slots. Three physical layer copies of the same packet are transmitted by each terminal. The
packet loss rate as a function of the channel load is depicted. The unfitness of both the EF and the waterfall approximations is
evident in this case.
going beyond the characterization of minimal stopping sets (STs). Specifically, we implement
an integer-partition based algorithm to find the possible user and slot profiles of stopping sets.
The algorithmic approach allows us to include more than 20,000 STs compared to ca. 60 STs
considered in [1]. This of course incurs additional computational complexity. Two observations
follow: on the one hand, the user degree distribution is normally defined offline while planning
the network so that increase in computing time is a limited issue. On the other hand, compared
to numerical simulation, the proposed approximation is still orders of magnitude faster.
The rest of the paper is organized as follows. The system model is introduced in Section
II. Section III presents the key ingredients defining the stopping sets and describes the SF
approximation of IRSA. The proposed SF approximation is compared with EF in Section IV,
and Section V concludes the letter.
II. SYSTEM MODEL
In this work, we consider a wireless uplink-only scenario where 𝑚 active users access the
common medium according to the IRSA protocol. Sampling the user degree distribution Λ(𝑥),
4. 4
defined as
Λ(𝑥) =
d𝑚
Õ
d=1
Λd𝑥d
, with 0 ≤ Λd ≤ 1 ∀d,
d𝑚
Õ
d=1
Λd = 1 (1)
each transmitter determines how many copies it sends within the 𝑛 time slots composing the
MAC frame. Transmission slots are selected uniformly at random and a maximum of d𝑚 replicas
are sent.2 Specifically, a user sends d replicas of its packet with a probability of Λd and each
data unit has a pointer to the position of its copies. The channel load G = 𝑚/𝑛 is defined
as the average number of users transmitting per time slot. We consider the collision channel
model, i.e. collision-free replicas are decoded with probability 1 while data units involved in
collisions are lost. At the receiver side, Successive Interference Cancellation (SIC) is employed
to possibly resolve collisions iteratively removing replicas of users that experience at least one
replica collision-free. We measure the performance in terms of PLR p𝑙 which is defined as the
number of non-recovered users divided by the total number of users transmitting.
III. ANALYSIS OF STOPPING SETS
In [6], it has been observed that the received MAC frame can be conveniently visualized as a
bipartite graph composed by two sets, users (UNs) and slots (SNs) connected by a set of edges
identifying the slots where replicas belonging to each UN are transmitted. Thus, the interference
cancellation iterative process can be tracked on the corresponding bipartite graph by identifying
SNs with a single edge connected to them and resolving the connected user, i.e. removing all
edges emanating by the UN. In fact, replicas transmitted collision-free can be correctly decoded,
thanks to the collision channel model assumption. Unfortunately, not all collision patterns are
resolved by resorting to SIC. Harmful collision patterns are named stopping sets (STs),3 and
determine the packet loss rate. It is of utmost interest to characterize and analyze them, as we
will do in the next Sections.
A. Stopping Sets and their User, Slot Profiles
Formally, a stopping set (ST) is a subgraph of the MAC frame in which no SNs has less than
two emanating edges. Let us focus on a specific ST S. In order to characterize the configuration
of users, slots and their interlace within S, we need to define:
2We assume that d𝑚 as a design parameter is selected such that d𝑚 ≤ 𝑛.
3The analogy with stopping sets of low parity check codes is evident and already highlighted in [9].
5. 5
UNs
SNs
A B C D
1
(1)
A B C
1 2
(2)
A B
1 2
(3)
Fig. 2. The 3 possible STs (excluding the possible isomorphisms) with 4 edges.
𝝂S 𝝁S
(1) [4, 0, · · · , 0] [0, 0, 0, 1, · · · , 0]
(2) [2, 1, · · · , 0] [0, 2, 0, 0, · · · , 0]
(3) [0, 2, · · · , 0] [0, 2, 0, 0, · · · , 0]
TABLE I
BN-SN PROFILES FOR STS WITH 4 EDGES.
• the user profile 𝝂S =
h
𝜈S
1 , · · · , 𝜈S
d𝑚
i
, where 𝜈S
d
is the number of UNs in S with degree d
and 𝜈S is the 𝐿1-norm of 𝝂S, i.e. 𝜈S =k 𝝂S k1;
• the slot profile 𝝁S =
𝜇S
1 , · · · , 𝜇S
𝑚
, where 𝜇S
𝑖 is the number of SNs in S with degree 𝑖 and
𝜇S is the 𝐿1-norm of 𝝁S, i.e. 𝜇S =k 𝝁S k1.
In Fig. 2 we present all possible STs with 4 edges, excluding the possible isomorphisms, where
UNs are denoted by capital letters and SNs are denoted by numbers. Fixing the number of edges
to 4, there are 3 possible SN-BN profiles causing STs. Since a SN belonging to a stopping set
has at least 2 emanating edges, there are a maximum of 2 and a minimum of 1 SN involved.
Configuration (1) sees 4 degree one UNs and 1 degree four SN, while ST (2) involves 2 degree
one and 1 degree two UN and 2 degree two SNs. Finally, ST (3) encompass 2 degree two UNs
and 2 degree two SNs. The corresponding user and slot profiles for the three configurations are
summarized in Table I.
B. Short Frame Packet Loss Rate Approximation
Let us define S𝑈 as the set of all possible stopping sets S and S ⊂ S𝑈 a subset thereof. Given
a user 𝑢, conditioned on 𝑚 users accessing the IRSA frame, the packet loss rate p𝑙 (𝑚) can be
6. 6
approximated as
p𝑙 (𝑚) = Pr
Ø
S∈S𝑈
𝑢 ∈ S|𝑚
(𝑎)
≤
Õ
S∈S𝑈
Pr {𝑢 ∈ S|𝑚} (2)
(𝑏)
≈
Õ
S∈S
Pr {𝑢 ∈ S|𝑚}
where (a) stems from the union bound, while (b) is the truncation to the subset S. Thus, we
will consider only the most relevant stopping sets S for the approximation of p𝑙 (𝑚), i.e. the STs
with a limited number of UNs and SNs. It shall be noted that compared to [1], we will consider
a larger set of STs. Focusing on a specific ST S ∈ S we can write [1]
Pr {𝑢 ∈ S|𝑚} =
𝑤
𝝂S, 𝝁S
𝑚
. (3)
We can now expand 𝑤
𝝂S, 𝝁S
, the expected number of unresolved users belonging to the ST
S, as
𝑤
𝝂S
, 𝝁S
= 𝛼
𝝂S
, 𝑚
𝛽
𝝁S
𝛾
𝝂S
, 𝝁S
𝛿
𝝂S
, 𝝁S
(4)
where
𝛼
𝝂S
, 𝑚
=
𝑚!
𝑚 − 𝜈S
!
d𝑚
Ö
d=1
Λ
𝜈S
d
d
𝜈S
d
!
; 𝛽
𝝁S
=
𝑛
𝜇S
1 , . . . , 𝜇S
𝑚
. (5)
In eq. (5), 𝛼 represents the number of ways in which 𝜈S users in the ST can be chosen from
the total 𝑚 transmitting nodes, taking into account the selected user degree distribution. While
𝛽 is the total number of combinations of 𝝁S slots belonging to the ST out of the total 𝑛. The
function 𝛾
𝝂S, 𝝁S
, representing the ratio between the number of STs that the user-slot profiles
𝝂S, 𝝁S
can generate over the total number of graphs which 𝝂S can lead to, can be explicitly
written as:
𝛾
𝝂S
, 𝝁S
=
𝑐
𝝂S, 𝝁S
Îd𝑚
d=1
𝑛
d
𝜈S
d
. (6)
Here 𝑐
𝝂S, 𝝁S
is the number of isomorphic graphs with profiles
𝝂S, 𝝁S
(see also [1] for
more details), which is computed numerically.
We define 𝛿
𝝂S, 𝝁S
(cf. [1]) as the probability of the remaining 𝑚 − 𝜈S users to connect
to the stopping set S so that a larger ST K ⊃ S does not appear. For example, a user that has
transmitted a packet in a singleton slot, can connect to the stopping set S. This case does not
constitute a new stopping set as that user can easily be recovered thanks to the singleton slot. This
7. 7
probability is assumed to be 1 in [1] which in most of the cases overestimates the PLR. Next,
we present a refined way to compute 𝛿
𝝂S, 𝝁S
. For any set S, let us define eS =
Íd𝑚
d=1
d 𝜈S
d
,
as the number of edges in S. Let T
S,e𝑚
be the set of all STs containing S with all and only the
SNs in S and with the number of edges not exceeding e𝑚 eS. The parameter e𝑚 is introduced
to keep the computational complexity of 𝛿 limited. We approximate 𝛿
𝝂S, 𝝁S
= 1 for eS = e𝑚
similarly to [1]. Instead, for all sets S with eS e𝑚 we have
𝛿
𝝂S
, 𝝁S
≈ 1−
Õ
K∈TS,e𝑚
𝛼
𝝂K
− 𝝂S
, 𝑚 − 𝜈𝑆
·
˜
𝛾
𝝂K
, 𝝂S
, 𝝁K
, 𝝁S
𝛿
𝝂K
, 𝝁K
(7)
for eS eK ≤ e𝑚
where 𝛼
𝝂K − 𝝂S, 𝑚 − 𝜈𝑆
in eq. (7) is the number of ways to select the users with the UN
profile 𝝂K − 𝝂S out of the 𝑚 − 𝜈𝑆 not in S, and with
˜
𝛾
𝝂K
, 𝝂S
, 𝝁K
, 𝝁S
=
˜
𝑐
𝝂K, 𝝂S, 𝝁K, 𝝁S
Îd𝑚
d=1
𝑛
d
(𝜈K
d
−𝜈S
d )
. (8)
In eq. (8), ˜
𝑐
𝝂K, 𝝂S, 𝝁K, 𝝁S
is the number of graphs that are isomorphic to K embedding the
ST S.
In order to compute 𝛿, one should define the maximum number of edges e𝑚 considered for
the ST. Starting from the ST with the maximum number of edges e𝑚, where we assume 𝛿 = 1,
one can proceed backwards removing one edge at a time till the ST of interest S as per eq. (7).
It has to be stressed that the expression in eq. (7) is an approximation to the exact 𝛿
𝝂S, 𝝁S
;
nonetheless, we show its tightness in the next section.
In order to compute the exact value of the packet loss rate, all possible stopping sets should
be considered. Even for small frames, the number would rapidly become intractable, yielding
unmanageable complexity. To limit it, we consider only STs that have up to e𝑚 edges.
IV. EVALUATION
We consider a maximum of 10 users sending at least two and at most four replicas, i.e.,
d𝑚 = 4. Thus, the total number of edges in the bipartite graph varies between 20 and 40. We set
e𝑚 = 20 as a sufficient trade-off between complexity and tightness in the approximation. Note
that in this way, only stopping sets that have up to 20 edges are considered.
8. 8
5 (G = 1) 15 20 25 30 35 40 50 (G = 0.1)
10−4
10−3
10−2
10−1
100
number of slots in a frame n
packet
loss
rate
p
l
simulation
EF [1]
SF
Fig. 3. Simulated packet loss rate vs. the EF approximation and the SF approximation in an IRSA scenario for Λ(𝑥) = 𝑥3 with
a fixed number of users equal to 5 and variable number of slots.
The simulations are conducted in a discrete time simulator designed in MATLAB.4 For each
frame, users generate a random number of replicas following the user degree distribution. Then
each replica is transmitted uniformly at random in the IRSA frame. At the receiver side, upon
storing the entire frame, SIC is performed to possibly resolve collision. At the end of the SIC
process the packet loss rate (PLR) is measured. The results presented for each configuration are
an average over 106 runs.
As illustrated in Fig. 1, our SF approximation provides a maximum relative error of 0.54 for
a channel load of G ≤ 0.7 compared to 0.83 of EF. In the unpractical range of PLR higher than
10−1, the approximation diverges. This is mainly due to the limited number of edges considered
in the approximation. In fact, at high load, stopping sets with more than 20 edges occur more
frequently. These results confirm that for the short frame regime our approximation is tighter
than the EF approximation.
Fig. 3 aims at evaluating the SF approximation with variable load and illustrates an IRSA
scenario with 5 users and a user degree distribution set to Λ(𝑥) = 𝑥3. The load is 1 ≥ G ≥ 0.1.
Within the load range the SF approximation leads to a maximum relative error of 0.43, much
4We plan to make the simulator open-source available for the camera ready version of the paper.
9. 9
5 10 15 20 25 30 35 40 45 50
10−3
10−2
10−1
number of slots in a frame n
packet
loss
rate
p
l
simulation
EF [1]
SF
Fig. 4. Packet loss rate computed with the EF approximation, the SF approximation and via numerical simulations. The user
degree distribution is Λ(𝑥) = 𝑥3 with G = 0.4 and a variable number of slots.
smaller than 0.73, the one achieved by the EF. For a channel load of 0.5 or below, the maximum
relative error is impressively reduced to 0.08 for the SF compared to 0.61 for the EF. Overall,
SF approximation outperforms the EF approximation with variable load and with a fixed number
of users.
Fig. 4 aims at evaluating the SF approximation with a fixed load and variable number of slots
and users. We set the load G = 0.4 users per slot and the user degree distribution to Λ(𝑥) = 𝑥3.
The frame size is in the range 𝑛 ∈ {5, . . . , 50} and the number of users varies in 𝑚 ∈ {2, . . . , 20}.
In this second setup, the EF approximation shows a maximum relative error of 0.49 that can be
reduced to 0.09 with the SF approximation.
The presented evaluations have shown a tighter match of the proposed SF approximation
compared to the EF. In order to leverage such benefits, we now exploit the SF to optimize the
user degree distribution. The target is to minimize the PLR p𝑙 for a given number of users 𝑚
and a fixed frame size 𝑛. To this end we fix 𝑚 = 5 users and 𝑛 = 10 slots. In order to have a
tractable problem, we limit ourselves to a degree distribution Λ(𝑥) = Λ2𝑥2 +(1−Λ2)𝑥4, where Λ2
is our optimization variable. Recall that Λ2 is the probability that a user transmits two replicas
within the MAC frame, thus 0 ≤ Λ2 ≤ 1. In our formulation, (1 − Λ2) = Λ4, the probability that
10. 10
0 0.2 0.3 0.5 0.6 0.7 0.8 0.9 1
10−2
10−1
Λ∗
2 Λ∗
2 Λ∗
2
p∗
l
Λ2
packet
loss
rate
p
l
simulation
EF [1]
SF
Fig. 5. Packet loss rate computed with the EF approximation, the SF approximation and by numerical simulations as a function
of Λ2. The scenario assumes 𝑛 = 10 slots, 𝑚 = 5 users per frame and Λ(𝑥) = Λ2𝑥2 + (1 − Λ2)𝑥4.
a user sends four replicas. The simulation results with EF approximation and SF approximation
are shown in Fig. 5. The probability Λ2 is depicted on the x-axis, while y-axis represents the
packet loss rate. The blue, the black and the red lines correspond to the EF approximation, the
SF approximation, and the simulation, respectively. As expected, the SF approximation follows
the simulation closely. Observe that we can numerically evaluate the extremal point for both
approximations. Since the curves are convex, determining the extremal point corresponds to
minimize the PLR. Once found the Λ2 that minimizes the PLR, we can compare it with the
minimum obtained via Monte Carlo simulations. For the SF approximation, the minimum PLR
is 0.0662, achieved for Λ∗
2 = 0.45. The minimum PLR with the EF approximation results in
p𝑙 = 0.0815, which is almost 24% more than the value with SF and is found for Λ∗
2 = 0.12.
The simulated minimum is p𝑙 ≈ 0.0655 that is only 10% lower than PLR achieved by SF
approximation and is obtained by Λ∗
2 = 0.385.
V. CONCLUSION
In this paper, we introduced the short-frame (SF) approximation for the PLR in IRSA.
Targeting IIoT applications with stringent latency constraints, an extension of the analysis in
11. 11
[1] is provided. Not only a larger set of stopping sets is included in the analysis, but also a
refinement is proposed. Along with the definition of the slot profile also the inclusion of non-
minimal stopping sets helps improving the approximation. Increased tightness of up to one order
of magnitude for frames till 50 slots is shown via numerical results. The user degree distribution
minimizing the PLR can be easily and reliably obtained with the SF even for very short frames,
where alternatives become loose. Additionally, an open-source algorithm is provided for the SF
approximation and can be exploited for more precise results by considering more stopping sets.
An interesting future direction is to consider real traffic profiles while embedding the user degree
optimization relying on the proposed PLR approximation.
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