Single Cell Resource Allocation For The Downlink Of Multiuser OFDM Systems

Modern communication application requires wireless communication systems to havevery high throughput, supporting a large number of users and meeting their Quality of Serve(QoS). Wherever, the limited wireless resource and complexion and unsteadiness ofwireless channel pose very serious challenges to the design of wireless communicationsystem. Orthogonal Frequency Division Multiplexing (OFDM) is considered to be amodulation with high frequency efficiency which could alleviate Inter-Symbol Interference(ISI) greatly[1]. Multiple Input Multiple Output (MIMO) technology makes good use ofspatial diversity gain so that it significantly enhances stability of wireless communication orincreases the channel capacity[2]. In multiuser OFDM system, users have different QoS andhave different channel attribute corresponding to each sub-carrier. This characteristic offerssystem with multiuser diversity[3]and requires a good method to assign users wirelessresource such as sub-carrier and transmitting power, so as to get the optical systemperformance.This paper is going to address wireless resource allocation problem in single celldownlink multiuser OFDM system. Firstly, introduction of some fundamental wirelesscommunication knowledge is presented, including attribute of wireless channel, MIMOsystem, OFDM system and MIMO-OFDM system. After that, single cell wireless resourceallocation problem is fully investigated, including not only unicast service of single andmultiple antenna systems but also multicast service of those systems.As for single cell downlink multiuser Multiple Input Single Output-OrthogonalFrequency Division Multiplexing (MISO-OFDM) multicasting system, this paper comesforward two algorithms basing on some present research. One of these two methods exploitsspace diversity strategy and the other exploits Space Division Multiple Access (SDMA). Asfor the first strategy, optimal allocation algorithm is also presented. Simulation shows thatthe two proposed methods achieved very good performance.