Efficient Multicast Scheme based on Hybrid ARQ and Busy Tone for Multimedia Traffic in Wireless LANs

Abstract

Multicast in wireless LANs (Local Area Networks) is very useful for transmitting multimedia traffic from a sender to a group of receivers. The IEEE 802.11 WLAN MAC (Medium Access Control) layer does not support reliable multicast since, for multicast transmissions, it has no control packets such as the RTS, CTS, and ACK, which are used for unicast transmissions. Several protocols have been proposed to provide reliable multicast transmissions. However, they are not efficient for IEEE 802.11 WLANs due to the large number of packet transmissions and the excessive control overhead caused by the use of a large number of control packets in the error recovery process. In this paper, we propose a simple and effective scheme. The proposed scheme combines FEC (Forward Error Correction) and ARQ (Automatic Repeat reQuest) to reduce a large number of packet transmissions and to provide data reliability in the IEEE 802.11 WLANs multicast environment. It then uses busy tones to improve efficiency by reducing the excessive control overhead. Performance evaluation is conducted using both numerical analysis and simulation. The results show that the proposed scheme has good performance in terms of normalized throughput and average delay.

Reliable and Energy Efficient Protocol for MANET Multicasting

“…Issues and challenges presented by MANET multicasting include the following [2][3][4][5][6][7][8][9][10].…”

“…This is a similar system to the system proposed in IEEE 802.11 [3], but we modify it to be convenient for MANETs. When we have several receivers, multicast transmission is very useful compared to unicast transmission to each receiver.…”

“…After that, the MS or cluster head continues sending other blocks with the same technique. The feedback request transmission is defined before the transmission based on the network congestion status; if the network status is excellent, it can be postponed to the end of the message to reduce the time needed for error recovery, while if the status of the network is not good, it is better to send a feedback request after a number of blocks have been transmitted [3]. This may cause extra time overhead compared to the original transmission of multicast without any method of providing reliability, but our proposal ensures a better level of reliability with an appropriate control overhead.…”

“…In our RMBTM model, we will use the same standard spacing frame that we will use in the routing discovery method which is SIFS to utilize using tones and avoid the collisions of these tones [3]. To provide reliability, the standard format of the threeway handshake is as follows: send, receive, and acknowledge (ACK); however, we will modify this format to be convenient to our tone-based system.…”