Analytical Model of Proportional Fair Scheduling in Interference-Limited OFDMA/LTE Networks

Abstract

Abstract-Various system tasks like interference coordination, handover decisions, admission control etc. in upcoming cellular networks require precise mid-term (spanning over a few seconds) performance models. Due to channel-dependent scheduling at the base station, these performance models are not simple to obtain. Furthermore, upcoming cellular systems will be interferencelimited, hence, the way interference is modeled is crucial for the accuracy. In this paper we present an analytical model for the SINR distribution of the scheduled subcarriers of an OFDMA system with proportional fair scheduling. The model takes the precise SINR distribution into account. We furthermore refine our model with respect to uniform modulation and coding, as applied in LTE networks. The derived models are validated by means of simulations. In additon, we show that our models are approximate estimators for the performance of rate-based proportional fair scheduling, while they outperform some simpler prediction models from related work significantly.

On the interference as noise approximation in OFDMA/LTE networks

“…Meanwhile, in [3] the SINR distribution is assumed as Gaussian distributed. Simulations and analytical evaluations from [4] showed that both these simplifications are very similar in rate prediction performance. On the other side, the SINR distribution is not exponential and a precise modelling of the SINR together with the consideration of the dynamic resource allocation has a significant divergence from the approximate model [4].…”

“…Simulations and analytical evaluations from [4] showed that both these simplifications are very similar in rate prediction performance. On the other side, the SINR distribution is not exponential and a precise modelling of the SINR together with the consideration of the dynamic resource allocation has a significant divergence from the approximate model [4]. Nevertheless, the work presented there did not consider multiple interfering sources which are in general present in practical LTE network deployments.…”

Inter-Cell Interference Mitigation in LTE-Advanced Heterogeneous Networks by Dynamic Subframes Assignment Guaranteeing Fairness

“…Some users who can't be allocated resources to, are in a completely outage state. It is necessary to suppress the inter-cell interference in the HetNets while guaranteeing the fairness of communication [11], [12]. Then the goal of optimization is no longer maximizing the number of users above the SINR threshold in the network.…”

Semi-static interference coordination in OFDMA/LTE networks

“…Considering the instantaneous SINR γj,n(t) as a random variable Zj,n, then from [7] the rate expectation Rj,n(p k,n (t)) for PFS based systems can be computed as:…”

“…So two fundamental problems are to be solved: (i) Modelling the expected system performance and (ii) Optimizing the power allocations accordingly. We have already addressed both these issues: In [7] we have addressed stochastic performance models for interference limited LTE systems. In [8] we have then fundamentally addressed the issue of solving the optimization problem.…”