Cross-layer enhanced real-time packet scheduling over CDMA networks

Most existing scheduling algorithms for real-time traffic in code division multiple access (CDMA) networks bound the bit error rate (BER) in order to guarantee the packet error rate (PER) of each packet. However, there is a tradeoff between PER and the packet drop rate (PDR) caused by delay violations, i.e., by slightly degrading the PER, more packets can be sent thus lowering PDR This paper defines a new problem for scheduling real-time traffic in time division multicode CDMA networks, which optimizes the PER and PDR jointly across the physical and link layers. These two metrics make up the total packet loss ratio (PLR). A novel cross-layer enhanced real-time packet scheduling algorithm is proposed to optimize the PLR experienced by each user in each frame, and distribute it fairly between users over the long term. Simulation results show that the proposed algorithm provides fairness in packet losses among users of different traffic classes, and achieves superior performance over previous algorithms in reducing PLR and increasing system capacity.