STATISTICS OF SIGNAL TO INTERFERENCE RATIO PROCESS AT OUTPUT OF MOBILE-TO-MOBILE RAYLEIGH FADING CHANNEL IN THE PRESENCE OF COCHANNEL INTERFERENCE

Dual-hop cooperative communications in interference-limited Rayleigh fading channel will be investigated in this paper. The paper considers the first- and second-order statistics of the signal to interference ratio process at the input of the destination mobile station. The exact closed-form expressions for the first-order statistical measures, the probability density function and cumulative distribution function, will be derived. We will also derive approximate closed form expressions for the second-order statistics, the level crossing rate and the average fade duration. The obtained theoretical results will be verified by the Monte-Carlo simulations

Cascade decode-and-forward : spatial diversity reuse in sensor networks

In this paper, we consider a wireless sensor network that involves sensory data hoping through multiple wireless relays to reach a central collection hub. In particular we improve the decode-and-forward cooperative relaying scheme. In this paper, we propose the Cascade-Decode-and-Forward, where the number of successful relays increases with each additional cooperation stage. The achieved effect is a cascade of relays that contribute towards achieving full spatial diversity at the destination. A novel relationship between the achievable bit error rate and delay is derived for the proposed scheme. The results show that a small delay constraint relaxation, the proposed scheme can achieve full diversity. As the delay constraint relaxes further, the protocol can achieve full diversity at signals levels 10–100 orders magnitude lower than the decode-and-forward protocol. The proposed protocol can dynamically trade-off transmission reliability with delay and the analysis has shown that a certain node connectivity density is required to achieve a cascading cooperation chain with an arbitrarily low data extinction probability

Outage Probability of Dual-Hop Multiple Antenna AF Relaying Systems with Interference

This paper presents an analytical investigation on the outage performance of dual-hop multiple antenna amplify-and-forward relaying systems in the presence of interference. For both the fixed-gain and variable-gain relaying schemes, exact analytical expressions for the outage probability of the systems are derived. Moreover, simple outage probability approximations at the high signal to noise ratio regime are provided, and the diversity order achieved by the systems are characterized. Our results suggest that variable-gain relaying systems always outperform the corresponding fixed-gain relaying systems. In addition, the fixed-gain relaying schemes only achieve diversity order of one, while the achievable diversity order of the variable-gain relaying scheme depends on the location of the multiple antennas.Comment: Accepted to appear in IEEE Transactions on Communication

Energy harvesting AF relaying in the presence of interference and Nakagami-m fading

Energy-harvesting relaying is a promising solution to the extra energy requirement at the relay. It can transfer energy from the source to the relay. This will encourage more idle nodes to be involved in relaying. In this paper, the outage probability and the throughput of an amplify-and-forward relaying system using energy harvesting are analyzed. Both time switching and power-splitting harvesting schemes are considered. The analysis takes into account both the Nakagami-$m$ fading caused by signal propagation and the interference caused by other transmitters. Numerical results show that time switching is more sensitive to system parameters than power splitting. Also, the system performance is more sensitive to the transmission rate requirement, the signal-to-interference-plus-noise ratio in the first hop and the relaying method

Outage Probability of Dual-Hop Selective AF With Randomly Distributed and Fixed Interferers

The outage probability performance of a dual-hop amplify-and-forward selective relaying system with global relay selection is analyzed for Nakagami-$m$ fading channels in the presence of multiple interferers at both the relays and the destination. Two different cases are considered. In the first case, the interferers are assumed to have random number and locations. Outage probability using the generalized Gamma approximation (GGA) in the form of one-dimensional integral is derived. In the second case, the interferers are assumed to have fixed number and locations. Exact outage probability in the form of one-dimensional integral is derived. For both cases, closed-form expressions of lower bounds and asymptotic expressions for high signal-to-interference-plus-noise ratio are also provided. Simplified closed-form expressions of outage probability for special cases (e.g., dominant interferences, i.i.d. interferers, Rayleigh distributed signals) are studied. Numerical results are presented to show the accuracy of our analysis by examining the effects of the number and locations of interferers on the outage performances of both AF systems with random and fixed interferers.Comment: 35 pages, 11 figures, accepted with minor revisions for publication as a regular paper in the IEEE Transactions on Vehicular Technology on 21/09/201

동일채널간섭이 존재하는 페이딩채널에서 무선 중계 네트워크의 성능 분석

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 8. 이재홍.무선 중계 기술은 차세대 통신 시스템에서 요구되는 높은 서비스 품질/데이터 전송률 달성을 위한 가장 중요한 기술 중 하나이다. 중계 기술이 갖고 있는 다양한 장점으로 인해 중계 기술은 지금까지 IEEE 802.16j 및 3GPP LTE-Advanced 등의 무선통신 시스템 표준에 반영되기도 하였다. 그러나 실질적인 무선 중계 네트워크의 프로토콜 개발을 위해서는 여전히 해결해야하는 많은 문제들이 있다. 특히 대형셀과 소형셀이 동시에 존재하는 중첩셀 네트워크에서 이웃한 대형셀 및 소형셀로부터 받게되는 동일채널간섭은 차세대 무선통신 시스템의 성능을 저하시키는 주요 제한 요소인데 아직 연구가 미흡한 실정이다. 또한 전이중 중계 네트워크에서 단말기의 송신안테나에서 수신안테나로 들어오는 동일채널 루프간섭은 전이중 중계 네트워크의 성능을 결정하는 중요한 요소로 추가적인 연구가 필요한 실정이다. 본 논문에서는 동일채널간섭을 포함한 양방향 중계 네트워크, 동일채널 루프간섭을 포함한 양방향 전이중 중계 네트워크 및 무선 인지 다중 홉 네트워크의 성능을 분석하며, 주요한 연구결과는 다음과 같다. 첫째, 셀룰러 환경에서 높은 주파수 재사용율로 인해 발생한 동일채널간섭이 존재하는 양방향 중계 네트워크의 성능을 분석한다. 이때 임의의 한 사용자가 불능 사건이 발생하는 시나리오(개별 사용자 불능), 전체 사용자가 동시에 불능 사건이 발생한 시나리오(전체 사용자 불능)의 두 가지에 대해 성능을 분석한다. 여기에서 각 시나리오에 대하여 개별 사용자 불능 확률 및 전체 사용자 불능 확률을 폐형으로 유도한다. 모의실험을 통해 얻어진 불능 확률이 유도한 불능 확률 값과 일치함을 확인한다. 또한 동일채널간섭을 발생하는 인접 셀의 사용자가 늘어날수록 개별 사용자 불능 확률 및 전체 사용자 불능 확률이 증가함을 확인한다. 둘째, 동일채널 루프간섭이 존재하는 전이중 양방향 중계 네트워크를 연구한다. 여기에서 두 전이중 방식의 사용자들이 전이중 방식의 중계기를 이용하여 서로 신호를 교환한다. 이때 각 단말기들은 자신의 수신 신호에서 루프간섭 신호의 추정치를 제거한다. 단말기들이 채널 상태 정보를 정확하게 혹은 부정확하게 알고 있는 경우에 전이중 양방향 중계 네트워크의 불능 확률을 정확한 적분 표현 및 근사적 폐형 표현으로 유도한다. 모의실험을 통해 얻어지 결과가 유도한 수식과 일치함을 확인한다. 셋째, 대형셀과 소형셀이 동시에 존재하는 중첩셀 네트워크를 연구한다. 특히 인접 대형셀 및 소형셀에서 발생한 동일채널간섭이 존재하는 무선 인지 기반 다중 홉 소형셀 네트워크의 불능 확률을 분석한다. 모의실험을 통해 얻어진 불능 확률을 통해 유도한 불능 확률을 검증한다. 유도한 불능 확률 값과 모의실험을 통해 얻어진 불능 확률 값이 일치함을 확인한다. 대형셀의 수가 증가할수록 불능 확률이 증가함을 확인한다.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

Outage Analysis Of Two-way Relaying In Interference-limited Af Cooperative Networks Over Nakagami-m Fading

This paper investigates the outage performance of dual-hop amplify-and-forward (AF) two-way relaying systems with multiple co-channel interferers at the AF relay and two noisy end-sources. Assuming a Nakagami-m fading environment, a highly precise, easy-to-compute closed-form approximate expression for the outage probability is derived. Our analysis allows for general operating scenarios with distinct Nakagami-m fading parameters and unequal average fading powers between the hops. Monte Carlo simulation results are presented to corroborate the tightness of the proposed approximations. © 2012 IEEE.561564Zhong, C., Jin, S., Wong, K.-K., Dual-hop systems with noisy relay and interference-limited destination (2010) IEEE Trans. Commun., 58 (3), pp. 764-768. , MarSuraweera, H.A., Garg, H.K., Nallanathan, A., Performance analysis of two hop amplify-and-forward systems with interference at the relay (2010) IEEE Commun. Lett., 14 (8), pp. 692-694. , AugLee, D., Lee, J.H., Outage probability for dual-hop relaying systems with multiple interferers over Rayleigh fading channels (2011) IEEE Trans. Veh. Technol., 60 (1), pp. 333-338. , JanDa Costa, D.B., Ding, H., Ge, J., Interference-limited relaying transmissions in dual-hop cooperative networks over Nakagami-m fading (2011) IEEE Commun. Lett., 15 (5), pp. 503-505. , MayHan, Y., Performance bounds for two-way amplify-and-forward relaying (2009) IEEE Trans. Wireless Commun., 8 (1), pp. 432-439. , JanLi, Q., Adaptive two-way relaying and outage analysis (2009) IEEE Trans. Wireless Commun., 8 (6), pp. 3288-3299. , JunGuo, H., Ge, J.H., Outage probability of two-way opportunistic amplify-and-forward relaying (2010) IET Electron. Lett., 46 (13), pp. 918-919. , JunGradshteyn, I.S., Ryzhik, I.M., (2007) Table of Integrals, Series, and Products, , 7th ed., San Diego, CA: AcademicRankov, B., Wittneben, A., Spectral efficiency protocols for halfduplex fading relay channels (2007) IEEE J. Select. Areas Commun., 25 (2), pp. 379-389. , FebYacoub, M.D., Nakagami-m approximation to the sum of M non-identical independent Nakagami-m variates (2004) IET Electron. Lett., 40 (15), pp. 951-952. , JulSimon, M.K., Alouini, M.S., (2005) Digital Communication over Fading Channels, , 2nd ed., John Wiley & Son