Analysis of duplexing modes in the IEEE 802.16 wireless system

The IEEE 802.16 standard defines two main duplexing modes: Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD). The FDD can be divided further into Full-FDD (F-FDD) and Half-FDD (H-FDD). F-FDD requires full duplexing support from subscriber stations and works with two frequency bands. TDD operates a single frequency band, but it does not need full-duplexing support. H-FDD is a combination of these: it works with two frequency bands and does not require full-duplexing support. The cost of this is a more complicated scheduling and added overhead. Still, H-FDD might be the only possible duplexing mode in some occasions. In this paper, these duplexing modes are compared and the H-FDD specific features, such as group balancing, are presented. The simulation results show that H-FDD does not quite match the performance of F-FDD or TDD. In the downlink direction, F-FDD and TDD have similar performance but in the uplink direction F-FDD can benefit from subchannelization gain with fewer bursts per frame.