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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 proportional(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 even for simple systems. In this paper, we present an algorithm that produces a compact representation of the reachable state(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)
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)
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)
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. As(More)
In the IEEE Wireless Access in Vehicular Environment (WAVE), the periodic broadcast of the basic safety message (BSM) enables proximity awareness in the vehicle-to-vehicle (V2V) context. To maximize the level of awareness and consequently the driving safety, the BSM transmission at the highest allowed rate is desired in principle. A caveat, however, is(More)
The IEEE 802.11 physical layer (PHY) supports multiple transmission rates with varying modulation and channel coding scheme. This feature allows the 802.11 wireless LAN (WLAN) to protect the throughput performance in face of dynamically changing channel condition. For instance, 802.11a standard has 8 PHY "modes" or rates. The procedure of selecting the best(More)