Analysis of Blocking Probability in a Relay-Based Cellular OFDMA Network (original) (raw)
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Ijca Special Issue on Wireless Communication and Mobile Networks, 2012
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This study investigates a relay-assisted orthogonal frequency division multiple access cellular system with joint consideration of direct and relaying paths. In this system, a novel implementation adopting full-duplex relaying is proposed for joint relay-destination selection, subcarrier and power allocation. This new implementation can be shown to significantly improve spectrum efficiency as compared with the conventional half-duplex relaying orthogonal frequency division multiple access. In addition, the proposed scheme enables flexible controllability on the tradeoff between system capacity and user fairness.
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Reuse Partitioning has been recently proposed as an effective inter-cell interference mitigation strategy for OFDMA cellular networks. However, mobility of users has been largely ignored in the system level analysis of these systems. To fill this void, in this paper, a teletraffic analysis of a Reuse Partitioning (RP) system is conducted in order to evaluate the impact of mobility on the performance of this kind of systems. Contrary to the previous related published works, in the present paper the analysis considers realistic users’ mobility conditions by means of a smooth random mobility model. Also, intra-cell handoff attempts from outside region to inside region are considered. Novel mathematical expressions for the new call blocking, handoff failure, and call forced termination probabilities are then derived. In addition, Multiple Fractional Channel Reservation is used as a prioritization scheme in order to maximize system capacity. Moreover, the best distribution of resources for each region within a cell is also found for different Radio Resource Management (RRM) strategies and mobility scenarios.
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The opportunities and flexibility in relay networks and orthogonal frequency-division multiple access (OFDMA) make the combination a suitable candidate network and air-interface technology for providing reliable and ubiquitous high-data-rate coverage in next-generation cellular networks. Advanced and intelligent radio resource management (RRM) schemes are known to be crucial toward harnessing these opportunities in future OFDMA-based relay-enhanced cellular networks. However, it is not very clear how to address the new RRM challenges (such as enabling distributed algorithms, intra-cell/inter-cell routing, intense and dynamic co-channel interference (CCI), and feedback overhead) in such complex environments comprising a plethora of relay stations (RSs) of different functionalities and characteristics. Employment of conventional RRM schemes in such networks will highly be inefficient if not infeasible. The next-generation networks are required to meet the expectations of all wireless users, irrespective of their locations. High-data-rate connectivity, mobility, and reliability, among other features, are examples of these expectations. Therefore, fairness is a critical performance aspect that has to be taken into account in the design of prospective RRM schemes. This paper reviews some of the prominent challenges involved in migrating from the conventional cellular architecture to the relay-based type and discusses how intelligent RRM schemes can exploit the opportunities in relay-enhanced OFDMA-based cellular networks. We identify the role of multiantenna systems and explore the current approaches in literature to extend the conventional schedulers to next-generation relay networks. This paper also highlights the fairness aspect in such networks in the light of the recent literature, provides some example fairness metrics, and compares the performances of some representative algorithms.
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In this paper, we quantify the expected symbol loss probability in mobile multi-hop relaying systems employing Orthogonal Frequency Division Multiple Access (OFDMA) Techniques. We obtain the expected number of collisions and calculate the probability of symbol loss when a conflict occurs between subcarriers of two or more non-transparent relay stations, as well as we calculate the average symbol loss probability in the system. Also, the proportion of symbol with degraded SNR is measured and the collision rate is calculated. Our analysis shows that the resulting collision due to the simultaneous use of a subcarrier in different non-transparent relay stations can be very significant in a multi-hop relaying communication system, and severely degrades the SNR, and affects the QoS support in the system.