Performance analysis of cooperative virtual multiple‐input–multiple‐output in small‐cell networks

Abstract

With the advent of small cell networks (SCNs) to support growing wireless data volumes and thus reduced cell sizes, cooperative communications are significantly facilitated. Applicable to 3GPP LTE-A, we propose a novel channel/queue-aware user pairing and scheduling scheme in a cooperative virtual multiple-input multiple-output (VMIMO) system. The queueing performance of the VMIMO system with the scheduling scheme is analyzed based on the finite-state Markov model (FSMM), and compared with that of non-cooperative systems. Bounds on the average queuing delay of users are derived by using a semi-definite programming (SDP) approach. The presented analyses are validated through comparing the analytical and simulation results. It is found that the introduced VMIMO pairing process is able to significantly reduce service delays, bringing on a positive impact of cooperative techniques on next generation wireless systems.

Performance analysis of cooperative small cell systems under correlated Rician/Gamma fading channels

“…In SCNs, due to the even shorter access distances between transmitters and receivers, the propagation channels are characterised by deterministic or LoS components [9]. On this basis, the Rician multipath model is well suited to characterise the fading fluctuation of LoS wireless environment [7,9,11]. Yet the shadowing fading effect is not taken into account within Rician model, whereas by prior study, the Lognormal (LN) shadowing model is a prevalent model to capture this [8].…”

“…To solve this problem, the LN shadowing is approximated by the mathematical friendlier Gamma shadowing, which is revealed to have a good fit to the experimental data [14,15]. Unfortunately, most of the existing studies only consider small-scale fading [7,9,10] or simply assume that large-scale fading (shadowing fading and path loss) is a priori constant [11,16]. Besides, the effect of correlation is not considered either.…”

“…In this paper, we pursue a detailed performance analysis of SCNs over correlated Rician/Gamma (RG) fading channels with zero-forcing (ZF) receivers. To the best of authors' knowledge, the relevant studies have been published in [9,11,19,20]. In [19], the lower bound on the achievable sum rate of multi-cell cooperative MIMO systems over Rayleigh/Lognormal fading channels was investigated, while its validity is challenged in the LoS propagation environment and the promising SCNs are not considered yet.…”

“…On similar grounds, Mirhosseini and Tadaion [20] studied the performance of dense SCNs with multi-antenna BS employing the spatial Poisson point process model but does not consider the Rician composite channel, correlation and shadowing fading. In [11], the queuing performance of cooperative SCNs was analysed based on the finite-state Markov model. With the aid of random matrix theory, Hoydis et al [9] presented an approximate expression for outage probability (OP) of cooperative SCNs over Rician fading channels.…”

“…With the aid of random matrix theory, Hoydis et al [9] presented an approximate expression for outage probability (OP) of cooperative SCNs over Rician fading channels. Unfortunately, the common characteristics of [9,11,20] are the lack of consideration of the shadowing fading, correlation, as well as the ZF receivers.…”