Uncoordinated real-time video transmission in wireless multicode CDMA systems: An SMPT-based approach

We consider the real-time transmission of encoded video from distributed, uncoordinated wireless terminals to a central base station in a multicode CDMA system. Our approach is to employ the recently proposed simultaneous MAC packet transmission (SMPT) approach at the data link layer (in conjunction with UDP at the transport layer). We consider the real-time transmission of both video encoded in an open loop (i.e., without rate control) and video encoded in a closed loop (i.e., with rate control). We conduct extensive simulations and study quantitatively the trade-off between video quality, transmission delay (and jitter), and number of supported video streams (capacity). We find that the simple-to-deploy SMPT approach achieves significantly higher video quality and smaller delays than the conventional sequential transmission approach, while ensuring high capacity. In typical scenarios, with SMPT the probability of in-time video frame delivery is more than twice as large as with sequential transmission (for given delay bounds). Our results provide guidelines for the design and dimensioning of cellular wireless systems as well as ad hoc wireless systems.