Analysis of power control for indoor optical wireless code-division multiple access networks using on-off keying and binary pulse position modulation

Wireless infrared optical code-division multiple access (W-OCDMA) is a new developing technique with many useful applications. Noting the limitation on power consumption and eye-safety requirements, wireless optical systems are power limited. Therefore control and efficient use of optical power is a key issue in analysis and design of these systems. Also, multi-user interference is the major source of impairment in these systems and power control is required to control and reduce this interference. Power control and the inevitable errors in its algorithms play an important role in design and implementation of these systems. In this article the authors study the uplink performance of W-OCDMA networks employing on-off keying (OOK) and binary pulse position modulation (BPPM) schemes without any power control algorithm. The performance improvement as a result of using perfect power control is calculated. Then, the impact of imperfect power control that is the result of channel estimation error is analysed. The results clearly illustrate that deploying a proper and accurate power control algorithm can increase network capacity and reduce network average power consumption. The authors show that systems with non-ideal power control still perform considerably better than no-power controlled systems.