Outage Probability in GSM-GPRS Cellular Systems With and Without Frequency Hopping

General packet radio service(GPRS) is designed for transmitting packet data andis supposed to take its radio resource from the pool ofunused channels of GSM voice services. Obviously, theintroduction of GPRS has an impact on the voice services.In this paper, we present a method to calculate theoutage probability of the GSM-GPRS network for bothnon-frequency hopping and frequency hoppingsystems. This method takes into account Rayleighfading, power control (with error), discontinuoustransmission, and frequency hopping (if applied). Theoutage probability of voice services affected by theintroduction of GPRS is discussed. The number ofunused voice channels allocated to GPRS depends on thedifference between the outage level of the existingGSM network and the maximum acceptable level. Thefrequency hopping system can accommodate more GPRStraffic than the non-frequency hopping system. Thepower control error has more impact on systemperformance when more channels are allocated to GPRS.Beyond our expectations, for the non-frequency hoppingsystem, the channels provided for GPRS are not muchdifferent between high channel occupancy and lowchannel occupancy of voice services. In contrast, for thefrequency hopping system, the system can provide morechannels for GPRS at low channel occupancy. The cellservice area decreases by about 10% 20% for eachadditional channel allocated to GPRS.     

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.     

Co-Channel Interference in Cellular Mobile Radio Systems with Coded PSK and Diversity

In this paper, the performance of coding and diversity in narrowband wireless cellular systems affected by fading, shadowing and co-channel interference is analyzed. We consider low-order diversity, that can be practically realized for both coherent and differential phase shift keying. We assume that the shadowing random processes affecting all transmitted signals do not vary appreciably over the transmission duration. Fading, on the contrary, is assumed to vary more rapidly. Our main focus here is on outage probability. After choosing a performance indicator, its expectation is taken with respect to fading and co-channel interference, conditionally on shadowing. Hence, the resulting average performance indicator is a random variable. The probability that this random variable exceeds a specified threshold defines the outage probability. We consider as performance indicators (i) the channel cut-off rate R₀ and (ii) the bit error rate P_b of an actual coded scheme. As we are interested in interference-limited, rather than power-limited systems, we evaluate both R₀ and P_b for very high signal-to-noise ratios. Results are parameterized by the frequency reuse factor and the diversity order.     

Constrained Power Control to Enhance the Capacity of Slotted DS-CDMA Cellular Systems

We propose and study the constrained power control scheme for direct sequence code division multiple access (DS-CDMA) systems supporting voice and data services. In the proposed scheme, the voice users are subject to the conventional power control, while the data users are subject to distance dependent transmit power constraint. Several power control profiles for data users are suggested to reduce interference within its own and neighboring cells. For given delay and outage probability requirements, we present an analytical framework to analyze the number of users that can be supported by the proposed scheme. The results are compared to the conventional power control scheme, where no such constraint is imposed. We derive new closed form expression for the interference correction factor for the constrained power control scheme. In addition, we show that the total interference power can be approximated by the log-normal distribution, and we evaluate the mean and variance of the log-normal distribution analytically. We also derive the distribution of the signal-to-noise ratios for voice and data users, which is useful in evaluating the user capacity for slotted DS-CDMA cellular systems with both delay and power constraints.

MIMO解码转发双向中继系统中的传输策略与中断概率分析

在多输入多输出(MIMO)解码转发(DF)双向中继系统中,分别设计了两种信道状态信息(CSI)情况下的系统传输策略,并推导了系统中断概率的闭合表达式.当已知完全CSI时,采用(最大比发送-最大比接收)MRT-MRC技术设计波束形成和合并向量;当未知完全CSI时,设计了基于有限反馈的传输策略,并采用随机向量量化和Grassmann两种码本进行数值仿真验证.仿真结论显示,所设计的双向中继传输策略的中断概率性能明显优于其他策略,所推导的闭合表达式能准确地表征系统中断概率性能.     

Improved Analysis of Co-Channel Interference in Cellular Communications Systems

1 Introduction The performance analysis of co-channel interferenceincellular systems has been actively researched in the lastfewyears , due to the rapid deployment and success ofsuch systems , and because of the scarce bandwidthwhich calls for very careful design tools in order to uti-lizeit most efficiently.Signal transmission over a mobilechannel often suffers fromshadowing effect ,causing byobstacles in the radio propagation, such as the build-ings .In a cellular mobile system,the problemis…     

Influence of Discontinuous Transmission and Power Control on the Average SIR and the Outage Probability of the Uplink of CDMA Systems

In this paper the impact of the voice activity detection process and the powercontrolsystem on the average signal-to-interference ratio (SIR) is investigatedconcerningthe uplink of a single cell code division multiple access (CDMA) based mobilecommunication system. In the literature lower bounds on the average SIR areoftenemployed. Here we show the applicability of such bounds. For this purpose theresultsobtained from these bounds are compared with results obtained fromsimulations.Especially, for a few number of subscribers the differences between the lowerboundand the exact values are significant. Furthermore, the variance of the SIR isinvestigated for different parameters. We found out that significantvariations occurwhich affect the outage probability. But, many authors often employ only theaverageSIR, e.g. for their capacity estimations. However, the variance of the SIR hasto betaken into consideration too.     

Outage Probability of Opportunistic Amplify‐and‐Forward Relaying in Nakagami‐m Fading Channels

We address the outage performance for the opportunistic amplify‐and‐forward relaying strategies under Nakagami‐m fading channels. A closed‐form expression for the outage probability is derived. Simulation results verify our theoretical solutions.     

Interference Mitigation in MIMO Systems by Subset Antenna Transmission

This paper investigates subset antenna transmission (SAT) for multiple-input multiple-output (MIMO) systems in the presence of strong dominant co-channel interferer. The capacity gain from SAT is investigated in the context of optimal antenna subset selection and power allocation. The SAT does not require channel state information of the co-channel interference, and achieves capacity gains by distributing the transmit power equally over a selected subset of the transmit antennas. The capacity gain of the SAT method is analyzed in terms of transmit power and eigenvalues of channel matrix, and its performance in V-BLAST MIMO systems with various signal constellations is evaluated by computer simulation.     

Outage performance of amplify-and-forward two-way relaying with asymmetric traffics

This letter conducts the outage analysis for an amplify-and-forward (AF) based two-way relaying by jointly considering outage events at the two senders with asymmetric traffics. Unlike the current research activities, our goal is to explore the impact of traffic asymmetry on the system outage probability. We first derive the exact expressions of outage probability for the AF scenario over Rayleigh fading channels. To gain more insight, approximated expressions are developed at high signal-to-noise ratio (SNR) region. After that we interestingly find that the asymmetry of system traffics has significant impact on the system outage probability and the outage probability in the system is determined only by the one-way channel or related simultaneously to the two-way links, depending on the level of asymmetry between the two senders’ information rates. Simulation experiments are done. The simulation results verify our propositions and validate the accuracy of our derived expressions.     

Performance of Reuse Partitioning in Cellular Systems with Mobile Users

Reuse partitioning (RP) is a simple technique that can be used to increase the traffic capacity in a cellular system. With RP, a cell is divided into several concentric regions, each associated with a different cluster size. In this article, a traffic model is developed to analyze the impact of mobile users on a two-region RP system using fixed channel assignment. The influence of user speed and cell size on the new call blocking probability, P_b, and the call dropping probability, P_d, is investigated. A simpler model that can be used to estimate P_b and P_d in some cases is described. The effect on system capacity of reserving some channels for handoff calls is also studied. It is found that even though prioritized handoff can reduce P_d, it may also degrade the capacity. The accuracy of the analysis is verified using simulation for three mobility models.     

SDMA系统FD方案阻塞率的仿真

现代无线移动通信系统广泛考虑采用空分多址（SDMA）多址接入技术来提高系统容量。比如在频分复用（FDMA）时分复用（TDMA）,码分复用（CDMA）。分析研究SDMA系统中的FD信道分配机制,给出了理论推导,并在此基础上进行了仿真。仿真结果表明：采用该机制以后,用户可以在同一时间共享同一信道。     

Rapid Access Protocols for Discontinuous Transmission in DS-CDMA Systems

In this paper, three reverse link access protocols (AP) enabling discontinuous transmission (DTX) in DS-CDMA personal communication systems are introduced and discussed. The first protocol is synchronous (SDTX-AP), and it uses a so-called synchronous reservation channel to accommodate access requests in a time slotted frame structure. The second uses an asynchronous approach (ADTX-AP) with a spread slotted ALOHA protocol for access requests; access request messages consist of a synchronizing preamble and a user identifier appendix. The third one employs a synchronous structure of overlapping slots, offset in time by a minimum interval (mini-slot) necessary to enable resolution of overlapping access probes sent by different mobile users (MSDTX-AP). Instead of using different spreading codes for different mobile transmitters, all transmitters are assigned the same spreading code to send their access request messages on the access reservation channel. Analysis considers the mean access delay and throughput of the protocols in a multipath fading channel. Numerical results indicate that at high values of offered traffic of access requests mean access delays of ADTX-AP and SDTX-AP are comparable. The mean access delay for the MSDTX-AP depends on the number of minislots or users within each frame, but its throughput is much higher than that of either SDTX-AP or ADTX-AP.     

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.     

Joint Opportunistic Spectrum Sharing and Dynamic Full Frequency Reuse in OFDMA Cellular Relay Networks

This paper considers the problem of spectrum sharing in orthogonal frequency division multiple access cellular relay networks. Firstly, a novel dynamic full frequency reuse scheme is proposed to improve the spectral efficiency. Different from the conventional full frequency reuse scheme which only allows the base station (BS) reusing the subcarriers in the specific regions, an improved full frequency reuse scheme is proposed to allow the BS reusing all the subcarriers in the whole BS coverage region to exploit additional multiuser diversity gain. In order to dynamically reuse the frequency resource among the BS and relay stations (RSs) to further improve the spectral efficiency, the adaptive subcarrier scheduling is introduced into the improved full frequency reuse scheme to obtain more multi-user diversity gain, which forms the proposed novel dynamic full frequency reuse scheme. Secondly, in order to further increase the system throughput, the opportunistic spectrum sharing scheme is introduced to allow the RSs selectively reusing the subcarriers among each other, which joint with the proposed dynamic full frequency reuse scheme to intelligently allocates the subcarriers originally reused by the BS and a RS to another suitable RS which can best improve the system performance after considering the additional interference. Thirdly, in order to select The optimal reusing combination scheme of BS and RSs to exploit more potential system performance, a heuristic approach based on genetic algorithm is proposed to search the optimal BS and RSs combination to opportunistically share the frequency resource. Simulation results show that the proposed dynamic full frequency reuse scheme can obtain high spectral efficiency, fine fairness and low outage probability compared to the conventional full frequency reuse scheme. Furthermore, the system performance can be improved when considering the opportunistic spectrum sharing among RSs. Finally, after adopting the genetic algorithm, the system performance can be greatly improved by the frequency reusing among the optimal BS and RSs combination.     

On Issues about the Application of MIMO in Mobile Cellular Communications

1　Introduction　Thenewgeneration (beyond 3G/4G)mobilecel lularcommunicationsystemneedstosatisfythehighcapacitydemandsdrivenbysomeapplicationssuchasInternetandmultimediaapplications.Insuchasystem ,thekeytoachievetherequiredratesinahighlylimitedradiospectrumresourceisinadoptionofnoveltransmissiontechniques,whichofferhighspectralefficiencyandhightransmissionreliabilityrelativetothecurrentsystems.Multiple InputMul tiple Output(MIMO)systemusingmultipleantennasattransmitandreceiveendcanincrease…     

Approximating the Outage Probability of the Pilot Channel for IS‐95‐Based Cellular CDMA Systems in the Soft Handover Region

This letter presents an approximation of the outage probability of the pilot channel that can be used for CDMA cell planning. The approximation can determine system parameters for soft handover in IS‐95‐based cellular CDMA downlink design. Computer simulations show that our analytical results agree with empirical results.     

Interference Modelling in DS/CDMA Cellular Systems Operating in a General Fading Environment

Multiple access interference and the mobile radio environment are the primary limitations on the performance of DS/CDMA cellular systems. This paper presents the analysis of a DS/CDMA cellular system operating in a general fading environment. In particular the issues of signal fading, multiple access interference, and power control are addressed. A computationally efficient statistical method is used in the estimation of system performance. It is assumed that the variability of each received signal can be represented by fast Nakagami_m fading plus slower log-normal shadowing. Average bit-error-rate (BER) and outage probability are estimated as system performance indicators. The analysis shows, that as the variability of the fast fading of the received signal reduces, the performance of the system improves. However, when the signal undergoes both fast fading and shadowing, it is largely the shadowing that determines system performance. Use of forward link power control (that compensates for the variability due to shadowing) results in minimal performance improvement. However, in the reverse link significant improvement in performance can be achieved using a similar power control scheme.     

全双工窃听者主动干扰的协作NOMA网络性能分析

研究了瑞利衰落信道下协作非正交多址系统的安全性能。通信过程由一个时隙构成,源节点向中继广播叠加信号,全双工中继使用串行干扰消除技术解码信号协助用户通信。假设存在潜在全双工主动窃听者,窃听者能够从中继处截获信息并同时向用户发送人工噪声进行干扰。基于上述假设,在高信噪比条件下,推导了安全中断概率的近似表达式,分析了各节点传输信噪比与功率分配因子对系统中断概率的影响,分析结果与蒙特卡洛仿真结果吻合。     

A New Dynamic Channel Allocation Scheme for Microcellular Systems

1IntroductionThetremendousgrowthofthemobileuserpopulahonrequiresefficientreuseofscarceradiospectrUmallocatedtomobilecommunications.InmobilenetWorks,co-channelinterferencecausedbyfrequencyreuseisthemostrestrainingfactorontheoverallsystemcapacity.Inthecurrentcellularsystems,themainideabehindchannelallocationistomakeuseofradiopropagationpathlosscharacteristicsinordertondnindzethecaacer-tointerferenceratio(CIR)andhencetoincreasetheradiospecmimreuseefficiency.MicrocellularsystemshaveshowngreatPO…