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— Today's IEEE 802.11 WLANs (Wireless LANs) provide multiple transmission rates so that different rates can be exploited in an adaptive manner depending on the underlying channel condition in order to maximize the system performance. Many rate adaptation schemes have been proposed so far while most (if not all) of the commercial devices implement a simple(More)
This paper analyzes the impact of different MAC (medium access control) and transmission rate adaptation schemes on wireless mesh networks. The considered protocols include three different MAC protocols specified in IEEE 802.11 standards, i.e., 802.11, 802.11e, and 802.11n, and three rate adaptation schemes, i.e., ARF (automatic rate fallback), RBAR(More)
Many rate adaptation algorithms have been proposed for IEEE 802.11 Wireless LAN devices and most of them operate in an open-loop manner, i.e., the transmitter adapts its transmission rate without using the feedback from the receiver. A key problem with such transmitter based rate adaptation schemes is that they do not consider the collision effect.(More)
WLAN technology has been shown a revolutionary development during the last decade. Recently popularized IEEE 802.11a/g-based products can support up to 54 Mbps PHY (Physical layer) rate and give much freedom to access the Internet wirelessly. However, the 802.11 MAC (Medium Access Control) protocol has relatively large overhead in order to robustly deal(More)
The performance of an IEEE 802.11 station heavily depends on the selection of an AP (Access Point) that the station is associated with to access the Internet. The conventional approach to the AP selection is based on the received signal strength called RSSI (Received Signal Strength Indication) from APs within the transmission range. This approach however,(More)
We propose QUEST (QUality ESTimation), a new method that accurately estimates IEEE 802.11 wireless link quality with no in-band signaling overhead. Existing link quality estimation methods either are based on hello exchanges by fixing or varying transmission rates or rely on the history (e.g., delivery ratio) of previously sent data packets in a(More)
Today, IEEE 802.11 wireless LAN (WLAN) has emerged as a prevailing technology for broadband wireless networking. Along with many emerging applications and services, the demands for faster and higher-capacity WLANs have been growing fast. We propose a new medium access control (MAC) scheme for the next-generation high-speed WLANs, such as IEEE 802.11n. The(More)
Recently, IEEE 802.11 wireless LAN (WLAN) has emerged as a widely accepted technology for broadband wireless networking. A WLAN handoff operation, which occurs when a wireless station (STA) changes its association from one access point (AP) to another, has not been well understood so far since the mobility has not been a major concern for typical WLAN(More)
While many existing rate adaptation schemes in IEEE 802.11 Wireless LANs result in severe throughput degradation since they do not consider the collision effect when selecting the transmission rate, CARA (Collision-Aware Rate Adaptation) [1] shows improved system performance thanks to its collision-awareness capability. In this paper, we propose two(More)
We provide a comparative analysis of various routing strategies that affect the end-to-end performance in wireless mesh networks. We first improve well-known link quality metrics and routing algorithms to enhance performance in wireless mesh environments. We then investigate the route optimality, i.e., whether the best end-to-end route with respect to a(More)