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OPNET Technologies © 2008 OPNET Technologies, Inc. |
Title: A Distributed Radio Channel Allocation Scheme For WLANs With Multiple Data Rates For IEEE 802.11 wireless LANs (WLAN) with multiple access points (AP), it is critical to allocate the limited number of radio channels dynamically and efficiently. In this paper, we present a new radio channel allocation (RCA) scheme for WLANs with multiple data rates. First, we propose a new algorithm to dynamically estimate the number of active stations by using the least square estimator (LSE), which is unbiased and has minimum variance. Second, we derive an expression to evaluate the impact of the co-channel stations of an AP on the channel utilization of the AP based on the number of equivalent co-channel stations, which is the difference between the numbers of stations that are sensed by and associated with the AP. Third, we develop a new distributed RCA (DRCA) that considers the changing number of active stations, the impact of co-channel interference (CCI), and different traffic demands for different APs, which have not been considered by the existing RCA schemes. Simulation results by using OPNET have demonstrated that DRCA quickly finds optimal or suboptimal channel assignments and improves overall channel utilization for about 15~50% for different AP layouts, as compared to the existing schemes.
Title: A New Radio Channel Allocation Strategy For WLAN APs With Power Control Capabilities This paper proposes a new framework for radio channel allocation (RCA) strategy for WLAN APs with power control capabilities. First, we formulate the RCA as a min-max optimization problem regarding channel utilization with constraints of data rate, channel quality, and transmission power. Second, we derive an expression to evaluate the channel utilization, which incorporates the condition of wireless channel, such as signal-to-noise (SNR) ratio and transmission power, in addition to the transmitting probability of a station. Third, we propose a new RCA algorithm that considers both link adaptation and power control mechanisms, in addition to the impact of co-channel interference (CCI) and multiple data rates, which have not been considered by the existing RCA schemes. OPNET software will be used to simulate various scenarios and demonstrate the effectiveness of the proposed strategy. Other Simulations: Teaching Graduate Courses Title: EEL-5784: Computer Network Design and Analysis and EEL-6xxx: Computer Networks II. The first one focuses on the topics including theoretical basis for data communications, transmission media; data link layer, medium access control sublayer, routing algorithms and protocols, protocol modeling and performance analysis, typical applications including the Internet, introduction to mobile and wireless networks, network traffic, quality of service (QoS), security issues, and other related areas. OPNET will be briefly introduced and used to demonstrate the concepts and methods used in the network design and analysis. The second one concentrates on the modeling and management of interconnected networks, including an IP backbone network, WLANs, and wireless ad hoc networks. Major topics include a) routing protocols: OSPF, BGP, MPLS, on-demand routing; b) QoS: IntServ, DiffServ, QoS routing; c) security: cryptography, PKI, IPsec, secure routing; d) management: fault management, intrusion detection, traffic modeling and performance evaluations. OPNET will be used to study the protocol performance, including MAC and routing protocols with different enharncements. Other courses that may also use OPENT include EEL-5591: Wireless Communications and EEL-5xxx: Advanced Topics in Computer Networks (offered once in a two-year plan).
OPNET Technologies, Inc. is a leading provider of solutions for managing networks and applications. OPNET's best-in-class solutions address application troubleshooting, application monitoring, network monitoring, network configuration management, network planning , and network simulation. OPNET’s solutions have been operationally proven in thousands of customer environments worldwide, including corporate and government enterprises, government and defense agencies, network service providers, and network equipment manufacturers. For more information about OPNET and its products, visit www.opnet.com. |
