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Performance evaluation of joint downlink scheduling in multi-cellular OFDMA systems based on IEEE 802.16a

The employment of the OFDMA transmission technique in broadband radio systems shows several benefits. Especially the exploitation of multi-user diversity with the help of sophisticated scheduling algorithms can significantly increase the system capacity. In this paper, the performance of joint scheduling of downlink data transmissions for access point sets is evaluated in a multi-cellular system. The latter is compared with an independent scheduling on orthogonal subchannel sets in the access points. The general MAC structure of the investigated system is thereby based on IEEE 802.16a. However, concerning the Physical Layer there is an important difference. In IEEE 802.16a, the exploitation of multi-user diversity is not possible since the OFDMA subchannel scheme is based on an interference and fading averaging approach. The technique examined in this paper in contrast can be regarded as an avoidance approach which is subject to diversity in the subchannel quality. A basic OFDMA scheduling algorithm, which is able to exploit multi-user diversity and provide fairness, is used both for the joint and for the independent scheme.