Analytical Evaluation of QoS in the Downlink of OFDMA Wireless Cellular Networks Serving Streaming and Elastic Traffic

The objective of the present paper is to build analytical methods for the evaluation of the quality of service (QoS) perceived by the users in the downlink of OFDMA wireless cellular networks serving streaming and elastic traffic. To do so, we first describe the resource (power and bandwidth) allocation problem and characterize its feasibility by some reference feasibility condition (FC). The QoS for FC may only by evaluated by simulations. To cope with this difficulty, we propose some sufficient feasibility condition (SFC) having the multi-Erlang form which permits analytical evaluation of the QoS. In particular, the blocking probability for streaming users can be calculated using Kaufman-Roberts algorithm. For elastic users, explicit expressions of the throughputs are obtained by using a multi-class processor sharing model. Moreover, we study the QoS in a network serving simultaneously streaming and elastic traffic. We validate this approach by comparing SFC's blocking probabilities to these simulated for FC. Moreover, we illustrate the proposed approach by solving the dimensioning problem; i.e., evaluating the minimal density of base stations assuring acceptable QoS of a given traffic demand per surface unit.