Real-time evaluation of EVM based Strict priority and round robin schedulers

摘要

While implementing the idea of multiuser diversity for a scheduling scheme in a real time Orthogonal Frequency Division Multiplexing (OFDM) system, one is immediately confronted with two issues: fairness and delay. In the ideal situation when users' fading statistics are the same, the total capacity of the system as well as the throughput of individual users are maximized. In reality, the statistics are not symmetrical; there are users who are closer to the Base station (BS) with a better average Signal to Noise Ratio (SNR). To improve the throughput, Packet Delivery Ratio (PDR) of multiple packet-data users should be maintained maximum while preserving the fairness. The main contribution of this research paper is the real time implementation of two novel EVM (Error Vector Magnitude) based Multiuser Scheduling algorithms such as EVM based Strict priority scheduler (ESPS), EVM based Round robin scheduler (ERRS). The proposed EVM based algorithms are evaluated by implementing it on the FPGA (Field Programmable Gate Array) based WARP (Wireless open- Access Research Platform) board. Resources were allocated depending upon EVM. Almost the two proposed schedulers gave good performance with and without AGC (Automatic Gain Control) in terms of PDR and fairness. ESPS had a resource starvation of best-effort traffic with low delay when compared to ERRS.