A new access point selection policy for multi-rate IEEE 802.11 WLANs.

International Journal of Parallel Emergent and Distributed Systems 05/2008; 23:291-307. DOI: 10.1080/17445760801930914
Source: DBLP

ABSTRACT In wireless local area networks often a station can potentially associate with more than one access point. Therefore, a relevant question is which access point to select \best" from a list of candidate ones. In IEEE 802.11, the user simply associates to the access point with the strongest received signal strength. However, this may result in a signican t load imbalance between several access points. Moreover, the multi-rate exibilit y provided by several IEEE 802.11 variants can cause low bit rate stations to negatively aect high bit rate ones and consequently degrade the overall network throughput. This paper investigates the various aspects of \best" access point selection for IEEE 802.11 systems. In detail, we rst derive a new decision metric which can be used for AP selection. Using this metric we propose two new selection mechanisms which are decentralized in the sense that the decision is performed by each station, given appropriate status information of each access point. In fact, only few bytes of status information have to be added to the beacon and probe response frames which does not impose signican t overhead. We show that our mechanism improves mean quality of service of all stations and better utilizes network resources compared to the conventional one implemented today in IEEE 802.11 devices. Also, the schemes are appealing in terms of stability and provide their performance improvement even for denser or lighter network congurations.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Voice over Internet Protocol (VoIP) application has observed the fastest growth in the world of telecommunication. VoIP is seen as a short-term and long-trem transmission for voice and audio traffic. Meanwhile, VoIP is moving on Wireless Local Area Networks (WLANs) based on IEEE 802.11 standards. Currently, there are many packet scheduling algorithms for real-time transmission over network. Unfortunately, the current scheduling will not be able to handle the VoIP packets with the proper manner and they have some drawbacks over real-time applications. The objective of this research is to propose a new Voice Priority Queue (VPQ) packet scheduling and algorithm to ensure more throughput, fairness and efficient packet scheduling for VoIP performance of queues and traffics. A new scheduler flexible which is capable of satisfying the VoIP traffic flows. Experimental topologies on NS-2 network simulator wereanalyzed for voice traffic. Preliminary results show that this can achieve maximum and more accurate VoIP quality throughput and fairness index in access point for VoIP over WLANs. We verified and validated VPQ an extensive experimental simulation study under various traffic flows over WLANs.
    International Journal of Mobile Network Communications & Telematics. 12/2011; 1(2).
  • [Show abstract] [Hide abstract]
    ABSTRACT: We consider the issues of mitigating interference and improving network capacity in wireless networks from the viewpoint of channel diversity. Multi-channel diversity allows multiple pairs to concurrently use the wireless medium, thus increasing the achievable capacity; this multi-channel diversity can then be fully utilized by enabling wireless nodes to dynamically switch their channels. However, the process of switching channels in a wireless transceiver incurs switching overhead, resulting in the degradation of the throughput performance. We propose a receiver-centric multi-channel MAC protocol (RcMAC) that allows nodes to efficiently utilize multiple channels by reducing unnecessary channel switching. Receiver-centric channel switching enables each sender node to asynchronously and independently switch channels to one where its intended receiver resides, without requiring explicit channel negotiation. Thus, the wait time at the control channel is reduced, in addition to the number of channel switchings, thereby improving channel utilization. As this scheme requires prior knowledge of which channel a node is switched to, each node cooperatively shares its channel usage information in order to recognize the channels that its neighboring nodes are using. Through extensive simulations, we show that the proposed MAC protocol significantly improves network throughput and reduces end-to-end delay compared with other multi-channel MAC protocols.
    Computer Communications 02/2013; 36(4):431–444. · 1.35 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Station-Access Point (STA-AP) association is an important function in IEEE 802.11 Wireless LAN (WLAN) management. We obtain an association policy that can be implemented in centralized WLAN management devices, or in STAs, by taking into account explicitly two aspects of practical importance: (a) TCP-controlled short file downloads interspersed with read times (motivated by web browsing), and (b) different STAs associated with an Access Point (AP) at possibly different rates (depending on distance from the AP). Our approach is based on two steps. First, we consider an analytical model to obtain the aggregate AP throughput for long TCP-controlled file downloads when STAs are associated at k different rates r1, r2, ..., rk; this extends earlier work in the literature. Second, we present a 2-node closed queueing network model to approximate the expected average-sized file download time for a user who shares the AP with other users associated at a multiplicity of rates. These analytical results motivate the proposed association policy, called the Estimated Delay based Association (EDA) policy: Associate with the AP at which the expected file download time is the least. Simulations indicate that for a web-browsing type traffic scenario, EDA performs substantially better than other policies that have been proposed earlier. Crucially, the improved performance is sustained even in realistic evaluation scenarios, where the assumptions underpinning the analytical model do not hold. To the best of our knowledge, this is the first work that proposes an association policy tailored specifically for web browsing. Apart from this, our analytical results could be of independent interest.
    IEEE Transactions on Network and Service Management 09/2012; 9(3):346-358.

Full-text (2 Sources)

Available from
May 29, 2014