Multimedia CDMA wireless network design: the link layer perspective

Multimedia traffic sources with tight latency constraint, arising in sessions such as data query, image and video transmissions, can be very bursty and are inefficient to be serviced with a dedicated high-speed link. On wireline networks, bursty traffic is statistically multiplexed to fully utilize the link capacity. In light of recent proposals for wideband CDMA (WCDMA) to service multimedia data, there is a similar need to develop wireless network architectures with flexible bandwidth allocation to facilitate statistical multiplexing. To address this issue, we compared the throughput performance of two promising WCDMA configurations, high speed CDMA (HS-CDMA) and multi-code CDMA (MC-CDMA). HS-CDMA assigns each user a single code with small spreading gain to enable a high transmission rate when it is needed. In contrast, MC-CDMA employs codes with a large spreading gain but permits a user to acquire more than one code. As expected, the throughput of a configuration depends on the receiver structure as well as the operation scenarios like power and SNR constraints. When matched filter receivers are applied, HS-CDMA fares better in most occasions. When multi-user receivers are used, both configurations deliver the same throughput except the situation when the total power is bounded