PDF Advanced Spatial Modulation Schemes: Performance Analysis and ... - ERNET

Rakhesh Singh Kshetrimayum from the Department of Electronics and Electrical Engineering for introducing me to this area of research. I am grateful to the head of the Department of Electronics and Electrical Engineering for providing me all the facilities to carry out my research work.

Abstract

FSO links are modeled as G-G channel, while RF links are modeled as Rayleigh fading channel.

List of Acronyms

DF Decode-and-Forward CF Compress-and-Forward PDF Probability Density Function CDF Cumulative Distribution Function RV Random Variable. DFTWR Bidirectional Decode and Forward Relay AFOWR Unidirectional Gain and Forward Relay AFTWR Bidirectional LOS Field of View Gain and Forward Relay.

List of Symbols

Introduction

Body Area Network Communication
FREE-SPACE OPTICAL COMMUNICATION 2
Free-Space Optical Communication

Beam Divergence
Ambient Light
Atmospheric Losses
Absorption

FREE-SPACE OPTICAL COMMUNICATION 4

Scattering
Atmospheric turbulence

Underwater Optical Wireless Communication
HYBRID FSO/RF COMMUNICATION 6
Hybrid FSO/RF Communication
Physical Layer Network Coding
Spatial Modulation
ADVANCED SPATIAL MODULATION 8
Advanced Spatial Modulation
Performance Analysis-Main Metrics and Applications
Organization of the Thesis
CONTRIBUTION OF THE THESIS 10
Contribution of the Thesis
CONTRIBUTION OF THE THESIS 12

Outage probability indicates the probability that the system may be in outage, that is, the probability that the system cannot successfully decode the transmitted symbols. Optical spatial modulation (OSM) for two-way decode-and-forward-relay-based FSO systems is presented in the next chapter (Chapter 4).

Spatial Modulation for RF Cooperative Com- munication

Cascaded α-µ Channel Model
Proposed System Model
PROPOSED SYSTEM MODEL 22
PERFORMANCE ANALYSIS 24
Performance Analysis

Lower Bound of Outage Probability

Upper Bound of Outage Probability

Asymptotic Analysis of Outage Probability Bounds

RESULTS AND DISCUSSION 34

Average Data Rate

Results and Discussion

Start with the partial product Z2=R1R2 and use Eq. 2.9) The variables are defined later in this section. For bitwise XOR operation the antenna index will be coded, for example in the case of NA= 2, antenna index 1 will be denoted by 0 and antenna index 2 will be denoted by 1. The encoded symbol sent by the relay to the source nodes. is given by: 2.32).

SNR (dB)

PLNCAFOWR

AFTWRSM-DFTWR

RESULTS AND DISCUSSION 36

Data rate (bps)

PLNC

SM-DFTWR

RESULTS AND DISCUSSION 38

The influence of different number of antennas at the source and relay node is investigated in Fig. It is also observed that when the number of antennas at the source node is 4 and only 2 antennas are present at the relay node, then the system performance is almost similar to that of a system with 2 antennas at all the source nodes. Again it can be observed that the performance of a system with 4 antennas at the relay node and 2 antennas at each source.

From this it can be deduced that the number of antennas at the relay node basically controls the system performance.

RESULTS AND DISCUSSION 40

SNR(dB)

CONCLUSION 42

Conclusion

Spatial Modulations for Body Area Network- Based Communication

Introduction
INTRODUCTION 44
INTRODUCTION 46
System Model
CHANNEL MODEL 48
Channel Model
MIXTURE OF GAMMA DISTRIBUTION 50
Mixture of Gamma Distribution
ASYMPTOTIC ANALYSIS OF SISO BAN COMMUNICATION 52
Asymptotic Analysis of SISO BAN Communication
Results
RESULTS 54 Table 3.5: Scenario 2 parameters for BMI2
RESULTS 56

BAN-based communications can be line-of-sight (LOS) or non-line-of-sight (NLOS) type. This challenging task can be solved by introducing a new distribution called mixture of Gamma (MG) distribution. The CDF of MG distribution can be obtained by integrating the PDF and can be written as in Eq.

We can observe that the integration of PDF function can be written in terms of Gamma function (Γ(αM Gi , βiM Gx)).

Running analytical results

Running 5MG approximation results Running simulation results

Cycling analytical results

Cycling 5MG approximation results Cycling simulation results

Cycling BMI 1 Running BMI 1

RESULTS 58

NEED FOR MIMO BAN COMMUNICATION 60

Due to the presence of more scattered groups in running activities, the running scenario gives poor performance compared to cycling activities. We can conclude from the results that the body shadow effect dominates in running due to greater movement of body parts.

Need for MIMO BAN Communication

ESM for BAN Communication

SMBM FOR BAN COMMUNICATION 62

SMBM for BAN Communication

In SMBM, only one RF chain is used at the transmitter, saving the cost of multiple RF chains being used simultaneously as in other MIMO techniques. The RF signal is modulated with source data transmitted through the antenna into free space. An RF switch is used to connect the single RF chain to the specific antenna according to the message bit.

At the receiver, the ML algorithm is used to decode the MAP index and the antenna used.

PERFORMANCE ANALYSIS OF MIMO BAN COMMUNICATION USING LN-4

Performance Analysis of MIMO BAN Communication using LN- 4 Distribution

Performance Analysis of MIMO BAN Communication using MG DistributionDistribution

ASYMPTOTIC ANALYSIS OF MIMO BAN COMMUNICATION 66

Asymptotic Analysis of MIMO BAN Communication

Results

RESULTS 68

The asymptotic results for Scenario II activities and different methods such as ESM and SMBM converge with the analytical and simulation results at high SNR values, thus validating our asymptotic analysis. In this figure, the asymptotic results for scenario I activities and different methods such as ESM and SMBM are presented. As it is evident from the BMI1 analysis that Scenario II gives distinct results between running and cycling, we have therefore only provided figures for Scenario II activities for the other BMI categories.

For category BMI2 and BMI3, running and cycling activities for scenario II are compared for ESM and SMBM methods.

RESULTS 70

Out of the two scenarios, Scenario II running performs the worst because in the case of side-by-side running, the body gets in the way of signal transmission leading to more body shadow effect. While in the case of Scenario I running, there is no body barrier to signal transmission as the subjects are behind each other and the devices are attached to the arms. Since the arms of the subjects are outstretched in case of cycling for both scenarios, the body shadow effect is therefore the same for both scenarios, as signal transmission is not hindered by body barrier.

This is attributed to the fact that body obstruction does not hinder signal transmission during cycling.

RESULTS 72

Parameters such as Tx, mf, QAM and spectral efficiency (ηSE) are varied to investigate their impact on system performance. It is observed that as the number of broadcast antennas increases, the system performance degrades. The effect of constellation scheme on system performance is investigated by considering 4-QAM and 16-QAM.

It is observed that the system performance improves similarly with a decrease in the number of transmitting antennas, number of RF mirrors and constellation size.

RESULTS 74

Conclusion

CONCLUSION 76

Optical Spatial Modulation for Free-Space Op- tical Communication

Modulation Schemes in FSO Communication
CHANNEL MODELS FOR FSO COMMUNICATION 78
Channel Models for FSO Communication

G-G Channel Model

OPTICAL SPATIAL MODULATION FOR FSO COOPERATIVE COMMUNICATION 80
Optical Spatial Modulation for FSO Cooperative Communication

Proposed System Model

Lower Bound of Outage Probability

Upper Bound of Outage Probability
Outage Probability Analysis for Direct System

Asymptotic Analysis
Results and Discussion

We must not forget that the probability of failure occurs when one of the two links (relay-source 1 or relay-source 2) fails. In the first phase, when the source nodes forward the message to the relay, the outage probability can be defined by the expression PoutR LB obtained from Eq. For the first stage, there may be an outage probability when any of the links fail (either the source 1-to-relay link or the source 2-to-relay link).

Asymptotic analysis can be performed for lower and upper bounds on the cutoff probability.

DFSOOSM-DFTWR

PLNC-LOG

DFSO-LOG

OSM-DFTWR

OPTICAL SPATIAL MODULATION FOR FSO COOPERATIVE COMMUNICATION 96

Thus, we can observe that the outage probability value increases as the SNR loss factor increases. OPTICAL SPATIAL MODULATION FOR FSO COOPERATIVE COMMUNICATION. turbulence increases, resulting in a weak signal being received at the receiver located far away. The asymptotic results converge with the analytical and simulation results for high SNR values, thus justifying our analysis.

It is pertinent to note that as the atmospheric turbulence increases, the Rytov variance value increases due to increase in value of the constant Cn2.

TRANSMIT LASER SELECTION FOR FSO COMMUNICATION 98

Moderate

Weak

Strong

Transmit Laser Selection for FSO Communication
TRANSMIT LASER SELECTION FOR FSO COMMUNICATION 100

Channel Model with Pointing Error

Proposed System Model for TLS and TLS-OSM

Complexity Analysis of TLS and TLS-OSM

Performance Analysis of TLS and TLS-OSM

Analysis of TLS-OSM System

Error Analysis of TLS and TLS-OSM
Asymptotic Analysis

Results

Thus, the first phase outage probability will be the product of outage probability of source-to-relay transmission and the outage probability of source-to-destination transmission. Hence, the second phase outage probability can be calculated as the product of outage probability of relay-to-destination transmission and the complement of outage probability of source-to-relay transmission. The failure probability for source-to-relay link is given by FγSR(γ¯γSRth), while the failure probability of the overall source-to-destination link (when all link failure occurs for source-to-destination) is given by hFγSD( ¯γγSDth )iNLS.

The outage probability for the overall relay-to-destination link (provided relay can successfully decode the message in the first phase) is given by hFγSRD¯γ γth.

Transmit source optical power (dBm)

TRANSMIT LASER SELECTION FOR FSO COMMUNICATION 116

Transmit optical power (dBm)

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 118

R =6, T=2TLS without OSM,

Advanced Optical Spatial Modulation Schemes for FSO systems

However, there exists a significant research gap in implementing such advanced OSM schemes for outdoor FSO communications. There is still a major research gap in the calculation method of BER for all these advanced OSM schemes in different domains. Another important factor, the pointing error for outdoor FSO communications, has been ignored in the literature when analyzing state-of-the-art OSM schemes.

There is no available work regarding the analysis of advanced OSM schemes in terms of energy consumption and cost.

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 120

System Model for Advanced Schemes of OSM
Optical Enhanced Spatial Modulation
Optical Improved Quadrature Spatial Modulation

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS. QPSK) and secondary constellation will be binary phase shift keying (BPSK). For the specific 4t6b OESM scheme, a total of 16 combinations are possible, of which the first 4 combinations are the same as those of OSM, with one optical source active. Double source activation is performed for the next 6 cases where symbol assignment is performed according to one of the secondary constellation schemes BP SKO, while the secondary constellation scheme BP SK1 is used for the next 6 cases.

Thus, the first four bits are used as control bits, corresponding to the decimal number 9, i.e.

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 122

Optical Generalized Spatial Modulation

C is defined as the control bits used to select the set of active laser sources and is defined by C =jlog2 NL. The set of valid laser patterns to be activated is given by K with dimension 2C.

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 124

Performance Analysis of Advanced OSM Schemes

The total noise variance (n) is calculated by adding the variances of the three types of noise. Its channel matrix has the dimension ND×NL and it is an element of the channel matrix that follows the G-G distribution with pointing errors as in Eq. The integration includes multi-dimensional integration across the channel gains from each laser to photodetector.

During detection of the laser index, the APEP (where the laser index j may be misdetected as i) for G-G channel may be with pointing errors.

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 126

It is interesting to note that closed form expressions are possible for laser index detection while not possible for symbol error detection. This is because laser index detection differs from one-dimensional channel gain, where laser index is held fixed and the photodetector index can vary at the receiver. PDF of such a summary of the difference of channel gains can be obtained as shown in Appendix for laser index tracking error.

The total BER of the system can either occur when there is an error in laser index estimation or when there is an error in symbol estimation.

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 128

Comparison of Performance Metrics

Therefore, the switch cost and switch power consumption are much lower for higher spectral efficiency in OESM, OGSM and OIQSM compared to OSM. Thus, for a larger value of NL required to obtain a larger value of ηSE, the total cost of OSM is greater than the cost of the proposed methods due to excessive switch requirements. The power consumption of OSM is relatively lower than other schemes, but this trend is not fixed for all values of spectral efficiency and modulation scheme.

In this case, we can clearly notice that the total power consumption of OSM will exceed that of the other advanced OSM schemes due to the excessive need for switches.

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 130

Results related to Advanced OSM Schemes

The performance of the proposed methods- OESM and OGSM is compared with that of OSM and other techniques used in literature, in terms of BER in Fig. BER was calculated over G-G channel assuming light fog and strong turbulence conditions, and 4-QAM modulation in [169]. Nopt = 2 and 4-QAM modulation is used for OGSM, 4-QAM is also used for OESM, while OSM uses 16-QAM to achieve the same spectral efficiency.

OESM and OGSM easily outperform OSM as OSM uses a higher modulation scheme which has closer spacing between constellation points, thus causing more symbol detection errors.

ADVANCED OPTICAL SPATIAL MODULATION SCHEMES FOR FSO SYSTEMS 132

It is observed that performance of OGSM and OESM decreases with increase in spectral efficiency as higher target data rates are difficult to achieve. It is relevant to note that OGSM with 3 optical chains outperforms OESM with 2 optical chains at the same spectral efficiency of 8 bpcu. This is because OGSM uses 4-QAM and OESM uses 16-QAM to achieve the same spectral efficiency.

Again for the same spectral efficiency of 6 bpcu, OESM with 2 optical chains outperforms OGSM with 2 optical chains.

CONCLUSION 134

Conclusion

Spatial Modulation for Underwater Optical Wire- less Communication

Introduction to UOWC
INTRODUCTION TO UOWC 136
Channel Model
AMPLIFY-AND-FORWARD BASED UOWC SYSTEMS 138
Amplify-and-Forward Based UOWC Systems

Outage Probability for One-Way Relay System (OWR based UOWC)

Outage Probability for Two-Way Relay System (UOWC TWR)

ASEP Calculation for UOWC AF Systems
PDF, CDF and Error Analysis using MG Distributions

Results for AF Based UOWC Systems

OPTICAL IMPROVED QUADRATURE SPATIAL MODULATION FOR UOWC 152
Optical Improved Quadrature Spatial Modulation for UOWC

Optical Improved Quadrature Spatial Modulation
Performance Analysis of OIQSM UOWC Systems

Complexity Analysis of OIQSM

Results of OIQSM Based UOWC Systems

Transmit Laser Selection Based UOWC Systems
TRANSMIT LASER SELECTION BASED UOWC SYSTEMS 162

Proposed System Model for TLS-Based UOWC Systems

Performance Analysis of TLS and TLS-OSM UOWC System

TLS-OSM System Analysis
TLS and TLS-OSM Error Analysis

Results for TLS and TLS-OSM UOWC Systems

The total energy required for transmission in the two time slots by SN and RN is 2E. The received signal rRD on DN at the end of the second time slot can be written as:. For the last step of the above equation, we split the integration limit into two parts: y = 0 to x and the other = x to ∞. The PDF and CDF of the terms are inserted from Eq. 5.3) to respectively obtain the following simplified equation: In this case, the 1/2 term is due to the full-duplex nature of the system.

The relay node can decode the message from the source node and forward it to the destination node.