Back to the list of Graduate Students Inverse Multiplexing of IS95 Traffic for Video Transmission
by
Mazda Salmanian
1997 M. Eng Thesis
Abstract
This thesis studies the transmission of video signals over an IS95 CDMA communication system through Rayleigh fading channels. The video encoder's (H.263-compliant) bit rate ranges from 16Kbps to 64Kbps with which the air interface (IS95) system copes by adapting and assigning more channels to the video users dynamically. We consider up to 8 channels at 9600bps per video user. A channel in the reverse direction (mobile to the base station) is identified by the ESN (Electronic Serial Number) mask of the mobile; whereas a channel in the forward direction (base-station to the mobile) is identified by its Walsh code spreader. Effect of power control, slow and fast fading, and channel utilization are studied through the simulation of several scenarios involving audio and video users. Power control is required to maintain a reliable communication channel, especially at low mobile speeds; however it is observed that video-users do not require power control and synchronization per channel like audio users do. The base-station manages the channels assigned to a video user as one, since their origins are co-located. The system operates reliably in fast fading environments where the fade duration is several times shorter than the interleaver's depth. It is also found that a video-user's channel utilization is more efficient than that of an audio user. It is concluded that such system can reliably support 2 video users in the forward and reverse traffic channels with the presence of 6 to 8 audio interferers.