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— It was recently shown that 802.11b MAC has an " anomaly " that the throughput of high bit-rate terminals in good channel condition is down-equalized to that of the lowest bit-rate peer in the network. In this letter, we analytically prove that the phenomenon can be cleanly resolved through configuring the initial contention window size inversely(More)
State explosion is a well-known problem that impedes analysis and testing based on state-space exploration. This problem is particularly serious in real-time systems because unbounded time values cause the state space to be infinite. In this paper, we present an algorithm that produces a compact representation of reachable state space of a real-time system.(More)
— Algorithmic approach to link adaptation for IEEE 802.11 networks such as Automatic Rate Fallback (ARF) is known to suffer from the inability to differentiate between collision and channel-induced error. In this paper, we propose a novel algorithm called COLA that overcomes the shortcoming and achieves near-optimal throughput over wide range of channel and(More)
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— The bandwidth efficiency of Voice over IP (VoIP) traffic on the IEEE 802.11 WLAN is notoriously low. VoIP over 802.11 incurs high bandwidth cost for voice frame packetization and MAC/PHY framing, which is aggravated by channel access overhead. For instance, 10 calls with the G.729 codec can barely be supported on 802.11b with acceptable QoS – less than 2%(More)
A fundamental issue in the automated analysis of concurrent systems is the efficient generation of the reachable state space. Since it is not possible to explore all the reachable states of a system if the number of states is very large or infinite, we need to develop techniques for minimizing the state space. This paper presents our approach to cluster(More)
—In this paper, we first show that various network attacks can cause fatal inflation of dynamic memory usage on packet processing computers. Considering Transmission Control Protocol (TCP) is utilized by most of these attacks as well as legitimate traffic, we propose a parsimonious memory management guideline based on the design of the TCP and the analysis(More)
ntuitive visualization of ongoing attacks is something that network administrators can make good use of, providing quick perceptual clues before other more complicated analyses kick in. We demonstrate in this article that such attack visualization can be surprisingly straightforward yet highly informative. Although there are numerous types of malicious(More)
—The already severe inefficiency problem in running VoIP on the IEEE 802.11-based wireless LAN is exacerbated in multi-hop networks due to spatial interference. This paper presents a novel scheme that significantly mitigates the effect of the interference by combining the inter-call aggregation and the pseudo-broadcast technique as used in network coding.(More)