Energy/throughput tradeoffs of TCP error control strategies

Today's universal communications increasing involve mobile and battery-powered devices (e.g. hand-held, laptop, IP-phone) connected over wired and wireless networks. Energy efficiency, as well as throughput are becoming service characteristics of dominant importance in communication protocols. The wide applicability of IP-networks/devices, and the wide range of TCP-based applications, have rendered TCP the de facto reliable transport protocol standard not only for wired, but also for wireless and mixed (wired/wireless) communications. TCP's congestion control algorithms have been refined to achieve higher throughput. Even with these modifications, however, TCP versions do not incorporate a flexible error recovery strategy that is responsive to distinct environmental characteristics and device constraints. We have compared the energy- and throughput-efficiency of TCP error control strategies based on results gathered from our implementation of TCP Tahoe, Reno, and New Reno. We show that, depending on the frequency and duration of the error, each demonstrates appropriate behavior under specific circumstances, with Tahoe more-or-less the most energy conserving of the three. None of them, however, possesses a clear-cut overall advantage that would render it the version of choice for wired/wireless heterogeneous networks.