Modeling and Analysis of Tcp Performance under Joint Rate and Power Adaptation in Multi-cell Multi-rate Wcdma Systems

This paper models and analyzes the performance of TCP (Transmission Control Protocol) under joint rate and power adaptation with constrained BER (Bit Error Rate) requirements for downlink data transmission in a multi-cell VSF (Variable Spreading Factor) WCDMA system. The performance of TCP in a wide area Internet environment is evaluated by using computer simulation considering both random user mobility with uncorrelated shadowing and directional user mobility with correlated shadowing. Since the shortterm fading (i.e., multipath fading) changes more rapidly compared to long-term fading (i.e., shadowing), multipath fading is assumed to be independent over successive adaptation intervals. System dynamics under multiple concurrent TCP connections is simulated for both the homogeneous (or uniform) and the non-homogeneous (or non-uniform) trafiic load scenarios in a multi-cell environment.