Performance Improvement of IEEE802.16-2004 System in Jamming Environment via Link Adaptation

Beginning with a study on the performance of IEEE 802.16-2004 based system in military specialized environment where jamming is prominence, this paper focuses on system performance enhancement in jamming environment via link adaptation. Two types of jamming are considered: multitone pilot jamming and partial-band jamming. The results of computer simulation show that the system is vulnerable to jamming. Further, multitone pilot jamming degrades the system performance more severely than partial-band jamming, when jamming resource is of limited power. A robust characteristic is observed from the standard newly defined operation mode, 'BPSK frac12', under most of the jamming scenarios. Accordingly, a practical mean carrier-to-interference-noise ratio (CINR) based link adaptation algorithm is proposed with merit that it requires no change to the current protocol. In the assumed jamming scenario, the system with link adaptation and systems with fixed operation mode are tested and compared. The simulation results verify that the system operating in jamming environment achieves performance improvement from both throughput and service stability aspects by applying the proposed link adaptation algorithm. A parameter 'imperfectness' is introduced to evaluate the algorithm. Higher efficiency is found in system under partial-band jamming. An optimal value of a used for estimating the mean CINR is proposed to be around 0.3