Performance of generalized selection combining for mobile radio communications with mixed cochannel interferers

The performance of generalized selection combining (GSC) space diversity for mobile radio systems in the presence of multiple cochannel interferers is studied. Two cochannel interference models are considered: 1) L cochannel interferers consisting of L-N Nakagami-m interferers and N Rayleigh interferers and 2) L cochannel interferers in which each interferer follows Nakagami-m distribution for a fraction of time and Rayleigh distribution for the remaining of time. The fading parameters of the Nakagami-m interferers are limited to integer values only. The desired signal is assumed to be Rayleigh faded. Also, all the desired signals and the cochannel interferers received on each branch are independent of each other. Closed-form expressions are derived for the probability density functions (pdfs) of the instantaneous signal-to-interference power ratio (SIR) at the output of the GSC for the two cochannel interference models. Using these SIR pdfs, closed-form expression for evaluating the outage probability and the average bit error probability (BEP) are subsequently derived. A differential phase-shift keying scheme is considered in the derivation. Numerical results showing the influences of various system parameters on the outage probability and the average BEP are then presented.published_or_final_versio

A heuristic algorithm for channel assignment in cellular mobile systems

This paper describes an efficient heuristic algorithm for the channel assignment problem (CAP) in cellular mobile systems. The channel assignment scheme proposed here is based on repetitive ordering of requirements in sequences. The performance of the proposed algorithm is verified by several benchmark problems and found to be superior than other existing methods. The study show that the proposed algorithm yields optimal assignment in most of the cases and near-optimal assignment in other cases.published_or_final_versio

Approximate BER performance of generalized selection combining in Nakagami-m fading

The error performance of generalized selection combining (GSC), which optimally combines the K highest signal-to-noise ratio (SNR) signals out of L total diversity signals, in Nakagami-m fading was recently evaluated using moment generating function (MGF) of the GSC output SNR. However, no single closed-form expression for the MGF exists for arbitrary K and L. In fact, closed-form expression for the MGF is possible only for individual combination of K and L. In this letter, a single closed-form expression for approximating the MGF is, therefore, derived and employed in evaluating the approximate error performance. Although the approximation is only applicable for GSC with K being a factor of L, it nonetheless achieves a high degree of accuracy.published_or_final_versio

Performance analysis of bandwidth efficient coherent modulation schemes with L-fold MRC and SC in Nakagami-m fading channels

This paper presents the average symbol error rates (SERs) of the 16-ary phase shift keying (16PSK), 16-ary amplitude phase shift keying (16APSK) and 16-ary quadrature amplitude modulation (16QAM) with L-fold maximal ratio combining (MRC) and selection combining (SC) space diversity receptions over Nakagami-m fading channels. Numerical results manifested error performance improvement when L-fold MRC and SC diversity receptions were employed. Error performance improvement attributed to an L=2 MRC diversity reception is comparable with that attributed to an L=4 SC diversity reception for the above three 16-ary modulation systems in a Nakagami-m fading channel with m of 5.published_or_final_versio

Analytical method to compute capacity improvement of dynamic channel assignment with power control

An analytical method is proposed to compute the capacity improvement of a dynamic channel assignment with power control (DCA/PC). A closed-form expression is derived to calculate the capacity of the DCA/PC, which is improved more than 150% compared with fix channel assignment (FCA) and dynamic channel assignment (DCA) with no power control. The theoretical and simulation results show good agreement, the difference being less than 7%.published_or_final_versio

Probability of symbol error for MPSK, MDPSK and noncoherent MPSK with MRC and SC space diversity in Nakagami-m fading channel

This paper derives analytically some simple closed form expressions for the average symbol error rate (SER) of M-ary phase shift keying (MPSK), M-ary differential phase shift keying (MDPSK) and noncoherent M-ary frequency shift keying (MFSK) over a Nakagami-m (1960) fading channel with L-fold maximal ratio combining (MRC) and selection combining (SC) space diversity reception. Numerical results demonstrate the error performance improvement by employing MRC and SC diversity reception in the above communications systems and show that MRC improves the error performance more significantly than does simple SC.published_or_final_versio

Performance analysis of IS-95 CDMA cellular system using noncoherent M-ary orthogonal modulation with other cell interference

The bit error rate (BER) performance of the M-ary DS/CDMA cellular system in the presence of an additive white Gaussian noise (AWGN) and interference from other cells has been investigated. The data frame structure of the IS-95 system was adopted. The system operated in an asynchronous mode with perfect power control and voice activity factor of 3/8. Both the hard handoff and the soft handoff were considered respectively. A close form expression for the BER performance has been derived for the single cell CDMA system whereas numerical integration was employed for the multiple cells CDMA systems instead.published_or_final_versio

Performance analysis of dynamic channel assignment with queuing and guard channel combined scheme for handoff prioritisation

An analytical method to calculate the performance of dynamic channel assignment with queuing and guard channel combined scheme for handoff prioritisation is proposed. Closed form expressions of the call blocking and handoff failure probability are respectively evaluated. The analytical and simulation results show good agreement.published_or_final_versio

Performance analysis of dynamic channel assignment for cellular mobile radio systems

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Cross layer designs for OFDMA wireless systems with heterogeneous delay requirements

This paper investigates a cross layer scheduling scheme for OFDMA wireless system with heterogeneous delay requirements. Unlike most existing cross layer designs which take a decoupling approach, our design considers both queueing theory and information theory in modeling the system dynamics. The cross layer design is formulated as an optimization of total system throughput, subject to individual user's delay constraint and total base station transmit power constraint. The optimal scheduling algorithm for the delay-sensitive cross layer optimization is to dynamically allocate radio resources based on users' channel state information, source statistics and delay requirements. Specifically, optimal power allocation was found to be multilevel water-filling where urgent users have higher water-filling levels, while optimal subcarrier allocation strategy is shown to be achievable by low complexity greedy algorithm. Simulation results also show the proposed jointly optimal power and subcarrier allocation policy can provide substantial throughput gain with all delay constraints being satisfied. © 2006 IEEE.published_or_final_versio