A Cross-Layer Optimization Semantic for Improving the Performance of TCP over CDMA Networks
Vasilis Friderikos, L. Wang, A.H. Aghvami · 2003
In this paper a novel joint power and rate adaptation scheme for CDMA networks is proposed that integrate information from the TCP state machine. The impetus behind this cross layer optimization approach is twofold. Firstly, to minimize the Round Trip Time (RTT) variation, by tracking the vary-ing transmission rate of TCP flows under a minimum power assignment. Secondly and most apropos, to adaptively allocate bit-energy-to-interference-power-spectral-density ratios (Eb/I0) to different flows based on the TCP state. By differential allocation of Eb/I0 values, flows with small size of congestion window (cwnd), which are more vulnerable to a retransmission through time out, are protected. In that sense, the proposed scheme tries to minimize the aggregate probability of time out events which have a deleterious effect on TCP performance. Additionally, in order to avoid the heavy computation overhead of an exhaustive search, a greedy algorithm is proposed which solves the optimization problem in linear time.