112 research outputs found
Performance analysis of diversity techniques in wireless communication systems: Cooperative systems with CCI and MIMO-OFDM systems
This Dissertation analyzes the performance of ecient digital commu- nication systems, the performance analysis includes the bit error rate (BER) of dier- ent binary and M-ary modulation schemes, and the average channel capacity (ACC) under dierent adaptive transmission protocols, namely, the simultaneous power and rate adaptation protocol (OPRA), the optimal rate with xed power protocol (ORA), the channel inversion with xed rate protocol (CIFR), and the truncated channel in- version with xed transmit power protocol (CTIFR). In this dissertation, BER and ACC performance of interference-limited dual-hop decode-and-forward (DF) relay- ing cooperative systems with co-channel interference (CCI) at both the relay and destination nodes is analyzed in small-scale multipath Nakagami-m fading channels with arbitrary (integer as well as non-integer) values of m. This channel condition is assumed for both the desired signal as well as co-channel interfering signals. In addition, the practical case of unequal average fading powers between the two hops is assumed in the analysis. The analysis assumes an arbitrary number of indepen- dent and non-identically distributed (i.n.i.d.) interfering signals at both relay (R) and destination (D) nodes. Also, the work extended to the case when the receiver employs the maximum ratio combining (MRC) and the equal gain combining (EGC) schemes to exploit the diversity gain
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μ μκ° μ¦κ°ν μλ‘ λΆλ₯ νλ₯ μ΄ μ¦κ°ν¨μ νμΈνλ€.Wireless relay technology is one of the most promising technologies for the future communication systems which provide higher data rate and better quality of service (QoS). Thanks to its advantages, it has been adopted in wireless standards such as IEEE 802.16j and 3GPP LTE-Advanced. However, there are still many challenges to be addressed for developing protocols of wireless relay networks. Especially, in multitier cellular networks (e.g. small cell underlaid macro cell), cochannel interference from multiple interferers in other macro cells and neighboring small cells is one of the major limiting factors due to frequency reuse for high spectrum utilization. In the full-duplex relay networks, cochannel loop interference from a transmit antenna to a receive antenna of a terminal is an important limiting factor to determine the performance of full-duplex relay networks.
The dissertation consists of three main results. First, we analyze the performance of a two-way relay network experiencing cochannel interference from multiple interferers due to frequency reuse in cellular networks. In the two-way relay network, two users exchange their information with the help of an amplify-and-forward (AF) relay. We discuss two different scenarios: Outages are declared individually for each user (individual outage) and an outage is declared simultaneously for all users (common outage). We derive the closed-form expression for the individual outage probability and the exact integral expression for the common outage probability of the two-way relay network with multiple interferers. The validity of our analytical results is verified by a comparison with simulation results. It is shown that the analytical results perfectly match the simulation results of the individual and common outage probabilities. Also, it is shown that the individual and common outage probabilities increase as the number of interferers increases.
Second, we investigate two-way full-duplex relaying with cochannel loop interference. In the two-way full-duplex relaying, two full-duplex users exchange data with each other via a full-duplex relay and each node attempts to subtract the estimate of the cochannel loop interference from its received signal. We derive the exact integral and approximate closed-form expressions for the outage probability of the two-way full-duplex relaying in case of perfect and imperfect channel state information. Monte Carlo simulation verifies the validity of analytical results.
Third, we investigate a cognitive small cell network which is overlaid with a cellular network. We analyze the performance of the cognitive small cell network in the presence of cochannel interference from the cellular network. Analytical results are verified by Monte Carlo simulations. It is shown that the analytical results are in complete agreement with simulation results. It is shown that the outage probability increases as the number of cells increases.Abstract
1 Introduction
1.1 Background and Related Works
1.1.1 Relay Technology
1.1.2 Cognitive Radio
1.2 Outline of Dissertation
1.3 Notations
2 Two-Way Relay Network with Cochannel Interference
2.1 System Model
2.2 Outage Probability Derivation
2.2.1 Moment Generating Functions
2.2.2 Individual Outage Probability
2.2.3 Common Outage Probability
2.3 Numerical Results
2.4 Summary
3 Two-Way Full-Duplex Relaying with Cochannel Loop Interference
3.1 System Model
3.2 Outage Probability Derivation
3.2.1 Signal-to-Interference-plus-Noise Ratio
3.2.2 Cumulative Density Function
3.2.3 Outage Probability
3.3 Numerical Results
3.4 Summary
4 Multi-hop Cognitive Radio Network with Cochannel Interference
4.1 System Model
4.2 Outage Probability Derivation
4.2.1 Signal-to-Interference-plus-Noise Ratio
4.2.2 Cumulative Density Function
4.2.3 Outage Probability
4.3 Numerical Results
4.4 Summary
5 Conclusions
5.1 Summary
5.2 Future Works
Bibliography
Korean Abstract
AcknowledgmentsDocto
Cooperative wireless networks
In the last few years, there have been a lot of interests in wireless ad-hoc networks as
they have remarkable commercial and military applications. Such wireless networks
have the benefit of avoiding a wired infrastructure. However, signal fading is a severe
problem for wireless communications particularly for the multi-hop transmissions in
the ad-hoc networks. Cooperative communication has been proposed as an effective
way to improve the quality of wireless links. The key idea is to have multiple wireless
devices at different locations cooperatively share their antenna resources and aid
each otherβs transmission.
In this thesis, we develop effective algorithms for cooperative wireless ad-hoc
networks, and the performance of cooperative communication is measured based
on various criteria, such as cooperative region, power ratio and end-to-end performance.
For example, the proposed interference subtraction and supplementary cooperation
algorithms can significantly improve network throughput of a multi-hop routing.
Comprehensive simulations are carried out for all the proposed algorithms and
performance analysis, providing quantitative evidence and comparison over other
schemes. In our view, the new cooperative communication algorithms proposed
in this research enable wireless ad-hoc networks to improve radio unreliability and
meet future application requirements of high-speed and high-quality services with
high energy efficiency. The acquired new insights on the network performance of
the proposed algorithms can also provide precise guidelines for efficient designs of
practical and reliable communications systems. Hence these results will potentially
have a broad impact across a range of related areas, including wireless communications,
network protocols, radio transceiver design and information theory
Performance Analysis of Multi-Antenna Hybrid Satellite-Terrestrial Relay Networks in the Presence of Interference
AbstractβThe integration of cooperative transmission into satellite networks is regarded as an effective strategy to increase the energy efficiency as well as the coverage of satellite communications. This paper investigates the performance of an amplifyand-forward (AF) hybrid satellite-terrestrial relay network (HSTRN), where the links of the two hops undergo Shadowed- Rician andRayleigh fadingdistributions, respectively.By assuming that a single antenna relay is used to assist the signal transmission between the multi-antenna satellite and multi-antenna mobile terminal, and multiple interferers corrupt both the relay and destination, we first obtain the equivalent end-to-end signal-to-interference-plus-noise ratio (SINR) of the system. Then, an approximate yet very accurate closed-form expression for the ergodic capacity of the HSTRN is derived. The analytical lower bound expressions are also obtained to efficiently evaluate the outage probability (OP) and average symbol error rate (ASER) of the system. Furthermore, the asymptotic OP and ASER expressions are developed at high signal-to-noise ratio (SNR) to reveal the achievable diversity order and array gain of the considered HSTRN. Finally, simulation results are provided to validate of the analytical results, and show the impact of various parameters on the system performance
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