Loss Differentiated Rate Adaptation in Wireless Networks

Abstract

Data rate adaptation is the process to select the optimal data rates for instantaneous channel conditions. This paper proposes a data rate adaptation technique that poses following traits: (1) it uses the periodical IEEE 802.11 beacons; (2) moreover, it distinguishes packet losses due to channel fading from those due to collisions and take actions appropriate for each type of loss; (3) in addition, it introduces the lowest data rate retransmission for the very first retransmission after packet loss. In traditional strategies, after a packet loss, retransmissions are often attempted with the same data rate. This work analytically shows that retransmitting at the lowest data rate is more efficient, especially in poor SNR environment or when there is no knowledge of the loss cause (channel degradation or transmission collision). This scheme, dubbed Loss Differentiated Rate Adaptation (LDRA), is extensively evaluated through simulations and shown to perform better especially when network collision is heavy.

Rate-adaptation for multi-rate IEEE 802.11 WLANs using mutual feedback between transmitter and receiver

“…Therefore, once the existing SNR is known, a suitable modulation technique (and thus a transmission rate) which can be decoded at the existing SNR can be selected [7][8][9][10][11][12][13][14][15]. SNR-based rate-adaptation schemes uses SNR measurements to estimate the quality of channel and such measurements are utilized for selecting a suitable transmission rate.…”

“…But nevertheless SNR based CSI is accurate and rate-adaptation schemes relying on SNR are relatively more robust. Therefore, to use the advantages of SNR for determination of CSI and at the same time to avoid modification in the standard frames, sender-side SNR based schemes were proposed [11][12][13][14][15]. Inspired from SampleRate [4] and SNR-based approaches, authors in [11] combine frame statistics information with SNR of ACK frames to select a transmission rate which gives highest throughput.…”

“…These extensions enhanced the PHY and MAC layer capabilities of the original standard. The IEEE 802.11 standard specifies transmissions at various rate, for instance, the Extended rate PHY (ERP), provides payload transmission support at 1, 2, 5.5, 6,9,12,18,24,36,48 and 54 Mbps. Two additional modes are defined to support payload transmission at 22 and 33 Mbps.…”

Increasing throughput in dense 802.11 networks by automatic rate adaptation improvement

“…According to the authors, this difference between simulation and experimental results probably comes from implementation issues with RTS/CTS that result in data frame losses even when the channel is reserved and is not limited by SINR. Some other works [5,7,8,11,13,20,35,39,48,51] are prone to a similar problem, since they were implemented only in a simulator and made strong assumptions that are hard to confirm using real hardware.…”

Adaptative Rate Issues in the WLAN Environment

“…In the case where one terminal is connected to an Access Point, some SNR information can be used to have a first idea of the channel quality, see Biaz & Wu (2008).…”