Design And Simulation Of Packet Scheduling Algorithms In MIMO-OFDM Systems

Future wireless communication systems require high reliability, high-speed data transmission. To meet Quality of Service (QoS) requirements of multiple services from voice to data, high spectral efficiency is needed to achieve rapid transmission for integrated services.The Orthogonal Frequency Division Multiplexing (OFDM) technology effectively decomposes a wideband channel into a set of narrowband orthogonal subcarriers. It not only reduces the interference between subcarriers, but also greatly improves spectral efficiency. Multiple-Input Multiple-Output (MIMO) technology can achieve high throughput by multiplexing gain and increase reliability by space diversity gain. Effective combination of both technologies can overcome the harmful effects caused by multipath and frequency selective fading and achieve high transmission reliability. It can also increase system capacity and spectral efficiency at the same time. OFDM and MIMO are two key candidates for the fourth generation mobile communication systems. Therefore, how to design packet scheduling algorithm supporting QoS requirements of multiple services for MIMO-OFDM systems has become the key task of radio resource management.This paper firstly proposes a packet scheduling algorithm considering users’QoS requirements. It is committed to satisfying delay requirements of real-time users and the available bandwidth requirements of non-real-time users. In order to avoid that some users always occupy subcarriers, users’priorities are affected by their historical subcarrier occupations. In order to improve the utilization of subcarriers, this paper also proposes a reallocation algorithm of subcarriers’sending abilities. After packet scheduling algorithm finishing the subcarrier allocation, the surplus sending ability needs to be reallocated to reduce the waste and improve system performance.This paper realizes the simulation platform by VISUAL C++6.0and Matlab2010b to verify the proposed packet scheduling algorithms and the reallocation algorithm of subcarriers’surplus sending abilities. Simulation results show that the proposed algorithms can better meet delay and available bandwidth requirements, compared with other algorithms.