A common strategy for energy saving in wireless network devices is to remain in sleep mode for as long as possible. The timing of packet transmission and reception depends on the behavior of the transport-layer protocols used by upper-layer applications. Therefore, understanding the relation between the behavior of the transport-layer protocols and energy efficiency using sleep mode is important for effective energy saving, especially when a wireless network interface (WNI) is activated in sleep mode at packet interarrivals. In this paper, we analyze the energy consumption of a client's WNI in Transmission Control Protocol (TCP) data transfer over a wireless LAN by focusing on the detailed behavior of TCP congestion control mechanisms. This model considers three situations: the WNI is activated in continuously active mode, in sleep mode, and in sleep mode with burst transmission. The latter is proposed as an effective method to improve energy efficiency, which lengthens sleep periods by transmitting and receiving multiple packets in a bursty fashion. Through numerical examples, we show that sleeping without modification of transmission timing reduces energy consumption in TCP data transfer by only around 10%, and that the burst transmission can contribute further 50% energy reduction.
- Transmission Control Protocol (TCP)
- energy consumption model
- energy efficiency
- wireless LAN