On the Performance of Slotted Aloha with Capture Effect in Wireless NetworksSlide 2Slide 3I. Two Core Interference Models in Wireless Networks and their FeaturesSlide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11II. Some Asymptotic Theoretical ResultsSlide 13Slide 14Slide 16Slide 17Slide 18Slide 19III. Power Control and Capture EffectSlide 21Slide 22Slide 23IV. Preliminary Simulation ResultsSlide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 311On the Performance of Slotted Aloha with Capture Effect in Wireless Networks On the Performance of Slotted Aloha with Capture Effect in Wireless Networks Arash Behzad and Julan HsuProfessor Mario GerlaCS218 ProjectUCLADecember 1, 2003 {abehzad,julan}@ee.ucla.edu2System ModelSystem ModelAssumptions: Slotted ALOHA Omni directional antennas Half-duplex radios Immobile nodes and fixed topological configuration (single access net) Assumptions: Slotted ALOHA Omni directional antennas Half-duplex radios Immobile nodes and fixed topological configuration (single access net) Objective: Analysis of the throughput performance of the Slotted Aloha medium access control for an arbitrary topology under variations of transmission probability (q) and transmission power level (P)Objective: Analysis of the throughput performance of the Slotted Aloha medium access control for an arbitrary topology under variations of transmission probability (q) and transmission power level (P)3Highlights of PresentationHighlights of PresentationHighlights of this presentation:i. Major interference models in wireless networks and their featuresii. Some asymptotic theoretical results iii. Power control and capture effect iv. Preliminary simulation resultsv. Conclusions Highlights of this presentation:i. Major interference models in wireless networks and their featuresii. Some asymptotic theoretical results iii. Power control and capture effect iv. Preliminary simulation resultsv. Conclusions4I. Two Core Interference Models in Wireless Networks and their Features I. Two Core Interference Models in Wireless Networks and their Features51. Protocol Interference Model1. Protocol Interference Model Assuming all nodes employ a common transmission range rc, transmission fromnode i1 to node j1 is successful ifand for every other node i2 transmitting in the same time slot rc and ri are commonly known as communication range and interference range, respectively. Assuming all nodes employ a common transmission range rc, transmission fromnode i1 to node j1 is successful ifand for every other node i2 transmitting in the same time slot rc and ri are commonly known as communication range and interference range, respectively. ,),(11 crjid .),(12 irjid j1j2j3i3i1i26 Let be the subset of nodes simultaneously transmitting at some time instant (time slot) employing an identical transmit power level. Then the transmission from a node , , is successfully received by a node , , if and only if whereby is the distance betweennodes and , N is the ambient noise power level, and is the path loss exponent. Let be the subset of nodes simultaneously transmitting at some time instant (time slot) employing an identical transmit power level. Then the transmission from a node , , is successfully received by a node , , if and only if whereby is the distance betweennodes and , N is the ambient noise power level, and is the path loss exponent. 2. Physical Interference Model 2. Physical Interference Model Wiikk,1iWi 1 1jWj 1,),(/),(/1111cWkikkjidPNjidP),(1jidk1jkij1j2j3i3i1i27Disadvantages of Protocol Interference Model: Aggregate Effect of Interference Disadvantages of Protocol Interference Model: Aggregate Effect of Interference -Illustration of a transmission scenario, which is feasible based on Protocol Interference Model and is infeasible based on Physical Interference Model. Note that all receivers are out of the “interference range” ri of non-associated transmitters. This problem can be resolved by Protocol Interference Model via considering a larger interference range in the expense of losing some spatial reuse. j1j2j3i3i1i2Feasible based on Protocol Interference Model, butinfeasible based on Physical Interference ModelFeasible based on Protocol Interference Model, butinfeasible based on Physical Interference Model8-Illustration of a transmission scenario, which is feasible based on Physical Interference Model (assuming i2 is sufficiently close to j2) and is infeasible based on Protocol Interference Model, since j2 is in the interference range of i1. j1i1i2j2Infeasible based on Protocol Interference Model, butfeasible based on Physical Interference ModelInfeasible based on Protocol Interference Model, butfeasible based on Physical Interference ModelDisadvantages of Protocol Interference Model: Capture Effect Disadvantages of Protocol Interference Model: Capture Effect9KEY ASSUMPTIONS:I. Protocol Interference ModelII. Identical transmit power level (no power control) III. Identical probability of transmission for all nodesKEY ASSUMPTIONS:I. Protocol Interference ModelII. Identical transmit power level (no power control) III. Identical probability of transmission for all nodesConventional Slotted Aloha in Wireless Networks Conventional Slotted Aloha in Wireless Networks 4AP/BN/BS2635110 Interference Model Assumptions: Protocol Model Interference Model Assumptions: Protocol Model Based on the Protocol Interference Model, transmission from node k to AP is successfully received if and only if it is the only transmission in the underlying slot. Why? Based on the Protocol Interference Model, transmission from node k to AP is successfully received if and only if it is the only transmission in the underlying slot. Why?1)1(1}1Pr{)(nqqnxnTH4 AP26351nq /1* Is it fair?Is it fair?11Interference Model Assumptions:Physical ModelInterference Model Assumptions:Physical Model What if we consider the Physical Interference Model? The throughput under Protocol Interference Model is higher or under the Physical Interference Model? Why? What if we consider the
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