Results 1  10
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114
Trusted Computer System Evaluation Criteria
 National Computer Security Center
, 1985
"... We develop a general model to estimate the throughput and goodput between arbitrary pairs of nodes in the presence of interference from other nodes in a wireless network. Our model is based on measurements from the underlying network itself and is thus more accurate than abstract models of RF propag ..."
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Cited by 61 (2 self)
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We develop a general model to estimate the throughput and goodput between arbitrary pairs of nodes in the presence of interference from other nodes in a wireless network. Our model is based on measurements from the underlying network itself and is thus more accurate than abstract models of RF propagation such as those based on distance. The seed measurements are easy to gather, requiring only O(N) measurements in an Nnode networks. Compared to existing measurementbased models, our model advances the state of the art in three important ways. First, it goes beyond pairwise interference and models interference among an arbitrary number of senders. Second, it goes beyond broadcast transmissions and models the more common case of unicast transmissions. Third, it goes beyond homogeneous nodes and models the general case of heterogeneous nodes with different traffic demands and different radio characteristics. Using simulations and measurements from two different wireless testbeds, we show that the predictions of our model are accurate in a wide range of scenarios.
Modeling 802.11e for Data Traffic Parameter Design
, 2006
"... This paper introduces a finite load multiclass 802.11e EDCF model that is simple enough to be explicitly solvable. The model is nevertheless flexible enough to model the impact of 802.11e parameters on the prioritization of realistic traffic. We emphasize that a modeling framework which allows nons ..."
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Cited by 21 (6 self)
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This paper introduces a finite load multiclass 802.11e EDCF model that is simple enough to be explicitly solvable. The model is nevertheless flexible enough to model the impact of 802.11e parameters on the prioritization of realistic traffic. We emphasize that a modeling framework which allows nonsaturated sources is essential in the study of realistic traffic. We apply the model to a situation of practical interest: competing TCP flows in an infrastructure network. The model allows us to make a principled selection of 802.11e parameters to resolve problems highlighted in this scenario. Model predictions and parameter selections are validated against simulation and experiment. The model is shown to be accurate and the parameters effective.
Aggregation With Fragment Retransmission for Very HighSpeed WLANs
, 2009
"... In upcoming very highspeed wireless LANs (WLANs), the physical (PHY) layer rate may reach 600 Mbps. To achieve high efficiency at the medium access control (MAC) layer, we identify fundamental properties that must be satisfied by any CSMA/CAbased MAC layers and develop a novel scheme called aggr ..."
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Cited by 16 (6 self)
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In upcoming very highspeed wireless LANs (WLANs), the physical (PHY) layer rate may reach 600 Mbps. To achieve high efficiency at the medium access control (MAC) layer, we identify fundamental properties that must be satisfied by any CSMA/CAbased MAC layers and develop a novel scheme called aggregation with fragment retransmission (AFR) that exhibits these properties. In the AFR scheme, multiple packets are aggregated into and transmitted in a single large frame. If errors happen during the transmission, only the corrupted fragments of the large frame are retransmitted. An analytic model is developed to evaluate the throughput and delay performance of AFR over noisy channels and to compare AFR with similar schemes in the literature. Optimal frame and fragment sizes are calculated using this model. Transmission delays are minimized by using a zerowaiting mechanism where frames are transmitted immediately once the MAC wins a transmission opportunity. We prove that zerowaiting can achieve maximum throughput. As a complement to the theoretical analysis, we investigate the impact of AFR on the performance of realistic application traffic with diverse requirements by simulations. We have implemented the AFR scheme in the NS2 simulator and present detailed results for TCP, VoIP, and HDTV traffic. The AFR scheme described was developed as part of the IEEE 802.11n working group work. The analysis presented here is general enough to be extended to proposed schemes in the upcoming 802.11n standard. Trends indicated in this paper should extend to any welldesigned aggregation schemes.
Modeling 802.11 Mesh Networks
"... We introduce a tractable analytic model of throughput performance for general 802.11 multihop multiradio networks subject to finite loads. The model's accuracy and utility is illustrated by comparison with simulation. ..."
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Cited by 12 (8 self)
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We introduce a tractable analytic model of throughput performance for general 802.11 multihop multiradio networks subject to finite loads. The model's accuracy and utility is illustrated by comparison with simulation.
The Achievable Rate Region of 802.11Scheduled Multihop Networks
 IEEE/ACM TRANSACTIONS ON NETWORKING
"... In this paper, we characterize the achievable rate region for any 802.11scheduled static multihop network. To do so, we first characterize the achievable edgerate region, that is, the set of edge rates that are achievable on the given topology. This requires a careful consideration of the inter ..."
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Cited by 11 (4 self)
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In this paper, we characterize the achievable rate region for any 802.11scheduled static multihop network. To do so, we first characterize the achievable edgerate region, that is, the set of edge rates that are achievable on the given topology. This requires a careful consideration of the interdependence among edges, since neighboring edges collide with and affect the idle time perceived by the edge under study. We approach this problem in two steps. First, we consider twoedge topologies and study the fundamental ways by which they interact. Then, we consider arbitrary multihop topologies, compute the effect that each neighboring edge has on the edge under study in isolation, and combine to get the aggregate effect. We then use the characterization of the achievable edgerate region to characterize the achievable rate region. We verify the accuracy of our analysis by comparing the achievable rate region derived from simulations with the one derived analytically. We make a couple of interesting and somewhat surprising observations while deriving the rate regions. First, the achievable rate region with 802.11 scheduling is not necessarily convex. Second, the performance of 802.11 is surprisingly good. For example, in all the topologies used for model verification, the maxmin allocation under 802.11 is at least 64 % of the maxmin allocation under a perfect scheduler.
Modeling the impact of buffering on 802.11
 IEEE Comm. Lett
"... A finite load, large buffer model for the WLAN medium access protocol IEEE 802.11 is developed that gives throughput and delay predictions. This enables us to investigate the impact of buffering on resource allocation. In the presence of heterogeneous loads, 802.11 does not allocate transmission opp ..."
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Cited by 8 (4 self)
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A finite load, large buffer model for the WLAN medium access protocol IEEE 802.11 is developed that gives throughput and delay predictions. This enables us to investigate the impact of buffering on resource allocation. In the presence of heterogeneous loads, 802.11 does not allocate transmission opportunities equally. It is shown that increased buffering can help this inequity, but only at the expense of possibly significantly increased delays.
On buffer sizing for voice in 802.11 WLANs
 IEEE Commun. Lett
, 2006
"... Abstract — The use of 802.11 to transport delay sensitive traffic is becoming increasingly common. This raises the question of the tradeoff between buffering delay and loss in 802.11 networks. We find that there exists a sharp transition from the lowloss, lowdelay regime to highloss, highdelay op ..."
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Cited by 8 (1 self)
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Abstract — The use of 802.11 to transport delay sensitive traffic is becoming increasingly common. This raises the question of the tradeoff between buffering delay and loss in 802.11 networks. We find that there exists a sharp transition from the lowloss, lowdelay regime to highloss, highdelay operation. Given modest buffering at the access point, this transition determines the voice capacity of a WLAN and its location is largely insensitive to the buffer size used. Index Terms — 802.11, voice, buffer. I.
Unsaturated Throughput Analysis of IEEE 802.11 in Presence of Non Ideal Transmission Channel and Capture Effects
 IEEE Trans. Wireless Commun
, 2008
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Modeling the 802.11e Enhanced Distributed Channel Access Function
 Proc. IEEE GLOBECOM’07
, 2007
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Verification of Common 802.11 MAC Model Assumptions
"... Abstract. There has been considerable success in analytic modeling of the 802.11 MAC layer. These models are based on a number of fundamental assumptions. In this paper we attempt to verify these assumptions by taking careful measurements using an 802.11e testbed with commodity hardware. We show tha ..."
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Cited by 7 (1 self)
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Abstract. There has been considerable success in analytic modeling of the 802.11 MAC layer. These models are based on a number of fundamental assumptions. In this paper we attempt to verify these assumptions by taking careful measurements using an 802.11e testbed with commodity hardware. We show that the assumptions do not always hold but our measurements offer insight as to why the models may still produce good predictions. To our knowledge, this is the first indetail attempt to compare 802.11 models and their assumptions with experimental measurements from an 802.11 testbed. The measurements collect also allow us to test if the basic MAC operation adhere to the 802.11 standards. 1