Generalized Cochannel Outage Analysis with DTX in PCS Channels

Spectrum limitations are often a deterrent for swift growth of cellular radio systems. Therefore, different technologies have been explored to enhance the Radio Frequency (RF) capacity as well as to improve the communication quality. Recent technologies suggest the use of Discontinuous Transmission (DTX) as a mean to achieve these goals. In this paper, we analyze and quantify the performance improvement which result from implementing DTX in microcellular systems. The performance criteria is chosen to be the outage probability of de signal to interference ratio. Closed form expressions are derived for outage probabilities for systems using discontinuous transmission. Results are obtained for generalized Nakagami(n)/Nakagami(m) channels as well as for Ricean/Nakagami(m) environments. Moreover, since DTX effectiveness depend on voice patterns, modified expressions are developed for average outage probabilities which take into consideration different voice activity factors.     

Multicellular Alamouti scheme performance in Rayleigh and shadow fading

In this paper, we study the performance of two downlink multicellular systems: a multiple inputs single output (MISO) system using the Alamouti code and a multiple inputs multiple outputs (MIMO) system using the Alamouti code at the transmitter side and a maximum ratio combining (MRC) as a receiver, in terms of outage probability. The channel model includes path-loss, shadowing, and fast fading, and the system is considered interference-limited. Two cases are distinguished: constant shadowing and log-normally distributed shadowing. In the first case, closed form expressions of the outage probability are proposed. For a log-normally distributed shadowing, we derive easily computable expressions of the outage probability. The proposed expressions allow for fast and simple performance evaluation for the two multicellular wireless systems: MISO Alamouti and MIMO Alamouti with MRC receiver. We use a fluid model approach to provide simpler outage probability expressions depending only on the distance between the considered user and its serving base station.     

Performance characterization of digital transmission systems withcochannel interference

This paper presents a general methodology for performance characterization of digital transmission systems in the presence of cochannel interference, as a function of the actual number of interferers (ranging from zero to infinity). The bit error probability in time-invariant channels and outage probability in time-varying quasi-stationary channels are discussed. More precisely, a general approach to an outage probability definition based on the concept of the outage domain is introduced. This allows the discussion of the relation to the other definitions which have appeared in the literature and the proposal of some new more accurate methods for the evaluation of outage probability. A suitable comparison between exact evaluation, the well-known Gaussian approximation, and the other new approaches proposed in this paper, is carried out to evaluate performance, bit error probability is suitably obtained for linearly modulated signals by adopting a semianalytical approach, and for nonlinear (e.g., continuous phase) modulation signals, by means of simulation. Finally, as an example, the different approaches to derive performance discussed in the paper have been applied to a linear microcellular scenario     

Performance Investigation of CDMA/PRMA with Imperfect Power Control in TDD Cellular Systems

This study investigates the performance of joint code-division multiple access/packet-reservation multiple access (CDMA/PRMA) with the consideration of imperfect power control in TDD-CDMA cellular systems, and compares with that of CDMA/PRMA with an assumption of perfect power control. Both voice and World Wide Web (WWW) Internet browsing traffic were considered. We have studied their performances in terms of packet loss probability, power outage probability and average access delay. The results show that the assumption of CDMA/PRMA with perfect power control is too optimistic and independent of cell radius. It might be valid when the cell radius is <500 m. In addition, the performance of CDMA/PRMA with imperfect power control is highly limited by the cell radius due to its constraint on transmission power levels. Therefore, careful study is required if CDMA/PRMA is used in TDD systems.     

Two-relay distributed switch and stay combining

We study a distributed version of switch-and-stay combining (DSSC) for systems that utilize two relays. In particular, four different scenarios are considered, depending on a) whether or not the source-destination channel is taken into account, and b) the type of relaying, i.e., decode and forward or amplify and forward. A performance analysis in terms of outage and bit error probability is presented, when operating over Rayleigh fading channels. Numerical results demonstrate that two-relay DSSC achieves the same diversity gain and outage performance as if the best relay is selected for each transmission slot, albeit simpler.     

Outage Performance with Handover Triggering in Cellular Mobile Networks

An approach to performance evaluation of cellular mobile networksis proposed, which includes the behavior of handover algorithmsin the computation of outage probability.In a general system scenario, with a central cluster and interferingbase stations, the average outage probability is computed along a trip of themobile terminal that involves crossing the boundary between adjacent cells.The effects of correlated co-channel interferersare accounted for in the computationof outage probability, as well as in the dynamics of a relative signalstrengthhandover algorithm.Numerical results are provided and discussed as obtained over a wide rangeof values of system parameters, namely cluster size and channel parameters.Trade-off curves are shown in terms of outage probability and cross-overpoint versus the average number of handovers, and possible design criteriaare outlined.It is also seen that the local outage analysis (without handover triggering)can be referred to as a lower performance bound in cases of practicalinterest.     

Simulation of digital transmission over mobile channels at 300 kb/s

Studies of digital transmission over typical urban and suburban mobile channels using simulations that employ a local area model for the time varying mobile channel impulse response are discussed. The digital transmission techniques of coherently detected and differentially coherent detected versions of quadrature phase-shift keying (QPSK), Gaussian minimum shift keying (GMSK), and coherently detected binary phase-shift keying (BPSK) over example mobile channels are presented. Two measures of performance are considered; the mean bit error ratio (and irreducible bit error ratio), which is used to compare the robustness of the various modulation methods to delay spread, and the outage probability, which provides a measure of the overall transmission quality as would be perceived by a user. Emphasis is placed on results obtained for GMSK, which is the modulation scheme to be employed in the Pan-European digital cellular mobile system. The effects of RMS delay spread on the mean bit error ratio, mean irreducible bit error ratio, and probability of outage are considered for different channel types     

中继辅助蜂窝系统中降低盲区呼叫中断率的性能分析

该文介绍了一种盲区环境下在传统蜂窝系统加入中继功能的系统结构,并且描述了在这种环境下系统的解析模型。然后在这个模型的基础上,通过数学解析得到这种中继辅助蜂窝系统的呼叫中断概率。最后通过数值分析和性能比较证明了在盲区环境中,与无中继辅助的传统蜂窝系统相比较,中继辅助蜂窝系统可以获得更低的呼叫中断率。并且分析了节点移动速度、呼叫平均服务时间和节点覆盖半径等系统参数对这两种不同蜂窝系统性能的影响。     

Outage Probability Analysis of Dual-Hop Decode-and-Forward Relaying Over Mixed Rayleigh and Generalized Gamma Fading Channels

In this letter, outage probability of dual-hop decode-and-forward (DF) relaying scheme is analyzed over mixed Rayleigh and generalized Gamma fading channels. Cooperation model considered in this work consists of a source, a relay and a destination. It is assumed that source-relay and relay-destination channels experience Rayleigh fading and generalized Gamma fading, respectively. Exact outage probability expression is derived and outage performance is illustrated for both direct transmission and DF relaying scheme.     

基于STBC的无线认知NOMA系统物理层安全性能研究

基于非正交多址接入（NOMA,Non-Orthogonal Multiple Access）的认知无线电（CR,Cognitive Radio）网络物理层传输面临主用户干扰和第三方窃听双重干扰威胁.本文提出利用空时编码（STBC,Space Time Block Coding）技术提高认知用户物理层安全性能,推导了任意认知用户的安全中断概率闭合表达式.通过蒙特卡洛仿真进行验证,结果表明,所提STBC-CR-NOMA相比未采用STBC编码方案的CR-NOMA可以明显提高用户的安全中断概率,且随着认知发射功率的增大,近端用户安全中断性能提高越大,而远端用户安全中断性能提升受认知基站发射功率的影响较小.仿真结果还表明,通过调整功率分配系数对远端用户和近端用户的安全中断性能影响不同.     

Radio resource management scheme and outage analysis for network-assisted multi-hop D2D communications

In a cellular network it's very difficult to make spectrum resource more efficiently. Device-to-Device (D2D) technology enables new service opportunities, and provides high throughput and reliable communication while reducing the base station load. For better total performance, short-range D2D links and cellular links share the same radio resource and the management of interference becomes a crucial task. Here we argue that single-hop D2D technology can be used to further improve cellular networks performance if the key D2D radio resource management algorithms are suitably extended to support multi-hop D2D communications. Aiming to establish a new paradigm for the analysis and design of multi-hop D2D communications, We propose a radio resource allocation for multi-hop D2D routes based on interference avoidance approach in LTE-A networks. On top of that, we investigate the outage probability of D2D communication. We first introduce a new definition of outage probability by considering the maximum distance to be allowable for single-hop transmission. Then we study and analyze the outage performance of a multi-hop D2D route. We derive the general closed form expression of outage probability of the multi-hop D2D routes. The results demonstrate that the D2D radio, sharing the same resources as the cellular network, provide higher capacity compared to pure cellular communication where all the data is transmitted through the base station. They also demonstrate that the new method of calculation of D2D multi hop outage probability has better performance than classical method defined in the literature.     

Outage Performance of MRT with Unequal-Power Co-Channel Interference and Channel Estimation Error

In this letter we investigate the outage performance of maximal ratio transmission (MRT) with unequal-power co-channel interference (CCI) and channel estimation error. The exact expression for the outage probability is presented. Our results are applicable to the MRT systems with arbitrary numbers of transmit and receive antennas.     

Statistical channel modelling and performance evaluation in satellite personal communications

This paper is concerned with channel modelling for satellite personal communications and with the associated problem of performance evaluation. Channel characteristics for personal communications tend to differ from those traditionally accepted for vehicular communications. In this paper we report on modelling aspects for both wideband and narrowband personal communications. Then we consider performance evaluation for low-altitude earth orbit (LEO) satellite systems in terms of bit error probability and outage probability. To evaluate the outage probability for LEO systems, a tight and simple upper bound is finally provided. © 1998 John Wiley & Sons, Ltd.     

Capacity analysis of a TDMA-based slow-frequency-hopped cellularsystem

Time-division multiple access (TDMA)-based systems have been adopted as the first generation digital cellular standards in North America, Europe, and Japan. The increasing demand for capacity motivates the study of alternate systems and enhancements to the adopted TDMA standards. In particular, CDMA techniques using direct sequence and slow frequency hopping have been suggested. We analyze the capacity of a slow-frequency-hopped TDMA-based cellular system via calculation of the outage probability. Expressions for the outage probability as a function of voice activity, power control, and antenna diversity are provided for mobile-to-base transmission. These expressions are used to evaluate the system capacity (users/MHz/cell) based on simulating mobile locations within 37 hexagonal cells. The sensitivity to power control error, voice activity factor, and soft capacity of the system is investigated     

Performance analysis of cellular mobile systems with successive co-channel interference cancellation

This paper presents an analytical framework for the performance evaluation of cellular mobile radio systems equipped with smart antenna systems. In particular, the paper focuses on low-complexity systems which are able to successively suppress the strongest active interferers. The desired user fading statistics is assumed to be flat Rayleigh, Rician, or Nakagami, whereas the interfering signals are assumed to be independent and subject to slow flat Rayleigh fading. The paper starts by presenting generic closed-form expressions for the the carrier-to-interference ratio probability density function after interference cancellation. Based on that, exact closed-form expressions for the outage probability and average error rate formulas are derived. Finally, a comparison with a practical cancellation scheme and the impact of some practical considerations on the performance of successive interference cancellation are investigated. More specifically, the effect of traffic loading, the overall spectral efficiency gain, and the impact of time delay are studied.     

Resource allocation for outage performance in heterogeneous networks: a matching game approach

In heterogeneous cellular networks (HCNs), the deployed small cell base stations share the same spectrum resource with that of macro base station, which causes cross-tier interferences and the performance depreciation of the system. This paper investigates the downlink outage performance of HCNs and its resource allocation problem to mitigate interferences. Specifically, we first derive closed-form expressions of overall outage probability of the system. Then, the resource allocation problem is proposed to reduce the outage probability of HCNs. This problem is formulated as a matching game, and a stable matching is considered to be the solution. Finally, to address this matching problem, a distributed algorithm is proposed which can find a stable matching. Both analytical results and simulations show that the proposed algorithm improves the overall performance of HCNs.     

Probability of error and outage in a Rice-lognormal channel forterrestrial and satellite personal communications

This letter addresses performance evaluation in a nonselective fading channel modeled by a combination of Rice and lognormal (RLN) statistics. The RLN model is valid under widely different environmental conditions, both for terrestrial cellular and for satellite personal communication systems. The letter provides semianalytical expressions for the average error probability in the RLN channel for coherent M-ary phase shift keying (PSK) and noncoherent M-ary orthogonal transmissions, then it highlights the relationship between outage probability and cell coverage for macro and microcellular systems, and finally it provides some error probability results for nongeostationary (non-GEO) satellite systems     

Power control and diversity in mobile radio cellular systems in thepresence of Ricean fading and log-normal shadowing

The performance of a cellular mobile radio system with frequency reuse is evaluated in terms of outage probability. Deterministic path loss, log-normal shadowing, and Ricean fading are accounted for, and the use of diversity and power control is considered in order to enhance system performance. Both hexagonal and lineal cells are considered. Particular attention is given to the sensitivity of the outage probability to the system parameters, especially those related to the propagation model (fading, shadowing, and path loss). It is seen that diversity and power control can improve the system behavior. The performance is sensitive to the fading parameter (i.e., the Rice factor) of the intended user, but is relatively independent of that of the interferers. Also, a significant dependence is observed on the shadowing parameter, whereas a limited dependence is seen on the outage threshold and the channel utilization. Finally, the presence of a dual path loss law degrades the performance, and the outage probability increases as the breakpoint distance gets larger     

Dual diversity combining and equalization in digital cellularmobile radio

The performance of digital data transmission over frequency-selective fading channels is investigated. For statistically independent diversity paths, estimates of average attainable error rates and outage probabilities as functions of system parameters are provided. The dependences among the important system parameters are exhibited graphically for several examples, including quaternary phase-shift keying (QPSK). In the optimized uncoded QPSK with 1.5 b/s/Hz, two orders of magnitude in outage probability can be gained by diversity reception. When one compares the uncoded average probability of error for the optimized mean squared error (MSE) systems one finds at most an order-of-magnitude difference among the different equalizers investigated except for the zero-forcing equalizer, whose performance is drastically inferior to the others. Again, dual diversity can provide two orders of magnitude improvement in the average error rate or in outage probability for the uncoded optimized systems