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...e lowest data rate, whereas with autorate unicast packets may be sent at a higher data rate. Hence the measured loss rates may not reflect the actual loss probability for unicast traffic. However, in =-=[17]-=-, we have shown that ETX in an autorate environment performs well despite this issue. One explanation is that the autorate algorithm inour cards only uses higher data rates if the loss rate is very s...

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... Intelligence Laboratory biswas, rtm @csail.mit.edu 133 Keywords wireless, mesh, 802.11 1. INTRODUCTION Multi-hop wireless networks typically use routing techniques similar to those in wired networks =-=[15, 16, 9, 4, 5]-=-. These traditional routing protocols choose the best sequence of nodes between the source and destination, and forward each packet through that sequence. In contrast, cooperative diversity schemes pr...

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...ller transmit timers, this benefit comes at a significant cost: the delivery ratio drops as low as 72%, which does not satisfy the reliability requirement. However, as the timer length increases past =-=[8,16]-=-ms, goodput drops significantly as the timer introduces idleness. Therefore, CTP Noe uses 7–14ms (1.5–3 average packet times) as its wait timer for the CC2420 radio. Similarly, CTP Noe uses 1.5–3 aver...

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... are new [1, 3, 2, 6], there has been no systematic evaluation of whether the architecture as a whole can achieve its goals. Prior evaluations of similar mesh networks have focused on routing metrics =-=[14]-=- and the radio-level causes of packet loss [7]. MANETs have been extensively studied [10, 19, 12], but their routing protocol design is focused on coping with rapid topology changes due to mobility. T...

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... using both simulations and measurements from real implementations running on a sensor network and an 802.11a Windows PC testbed. The Windows implementation modifies the Mesh Connectivity Layer (MCL) =-=[10]-=- to support VRR. The VRR network appears to an unmodified TCP/IP protocol stack as a single virtual link. Therefore, all IP-based applications can be run over the VRR network without modification. The...

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...networks. In general, ad hoc networks have recently received a great deal of attention and the issues of power and rate control have been also studied in the context of ad hoc routing protocols, e.g. =-=[18, 8, 28, 11]-=-. There are, however, significant differences between ad hoc networks and chaotic networks. First, ad hoc networks are multi-hop while our focus is on AP-based infrastructure networks. Moreover, nodes...

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...nimum weight paths and ensuring loop-free routing. Third, we show how to use these four requirements to analyze the performance of five existing routing metrics for mesh networks: hop count, ETX [3], =-=[4]-=-, ETT [5], WCETT [5] and MIC [6]. Our simulation results confirm our analytical results. The remainder of the paper is organized as follows. Section II investigates the possible types of routing proto...

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...the dependency of reception rates over time with respect to a variety of parameters. There are also several important empirical studies using medium-power RF radios in indoor and outdoor environments =-=[12, 13]-=-. These studies use 802.11 wireless radios. Aguayo et al. [12] measured the temporal variability of the packet reception rate for very short time scales (from 10 ms to 10 seconds) showing that the pac...

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...nsider concurrent packet transmissions. Many of these are orthogonal to our work in that they pertain primarily to the evaluation of different routing metrics in the presence of multiple flows (e.g., =-=[4, 7, 33]-=-). Kochut et al. [19] empirically study capture effect in 802.11b and show that the stronger signal can still capture a channel even when it does not arrive first at the receiver if it is still earlie...