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An Efficient Method For Hop Selection And Capacity Enhancement In Multi-Hop Wireless AD-Hoc Networks
Xiaohua (Edward) Li and Juite Hwu Department of Electrical and Computer Engineering State University of New York at Binghamton
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1.Introduction Multi-hop transmission Benefit: Deficit:
Make network flexible, Create larger network Save the energy of source node. Deficit: Increase the complex of system Interference from other nodes
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1.Introduction (cont' ) Our objective for this paper
Deal with mutual interference Derive the SINR of each node Locate the best path which provides the maximum capacity under mild conditions.
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2.System Model Consider a H-hop wireless network with J+1 nodes in a LхL meters square (H≤J) Let each node have a transmission power p Node i receives signal power pdij-α node j dij: distance between node i and j α: path-loss exponent
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2.System Model: slotted transmission protocol
1 2 ….. k Node 0 Tx Pk 0 Tx Pk 1 Tx Pk 2 Tx Pk k Node 1 Rx Pk 0 Rx Pk 1 Rx Pk 2 Tx Pk k-1 Rx Pk k : Node j Tx Pk k-j Rx Pk k-j+1
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2.System Model: received signal of node i
dij: distance between node i and j α: path-loss exponent u: signal of packet k v: noise N: power of noise
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3. SINR Analysis and Optimization
Slot # ….. k-1 k : Node j-1 Tx Pk k-j Rx Pk k-j+1 Node j Rx Pk k-j Node j+1 Signal known by Node j Simplify the received signal
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3. SINR Analysis and Optimization (cont’)
SINR of node j at time slot k SINR of node j at time slot k-1 Notice: here we track the same packet u(k-j+1)
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3. SINR Analysis and Optimization (cont’)
For the detection of u(k-j+1) Apply maximal ratio combing (MRC) to find the maximum SINR of yj(k)
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3. SINR Analysis and Optimization (cont’)
Calculate the overall SINR with MRC Notice: This SINR is for a node j in an H-hop when detecting packets
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3. SINR Analysis and Optimization (cont’)
Calculate the Capacity Like a water pipe, the capacity is limited by the minimum tunnel Find the max one, we can get the best transmission hopping path
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4. Hop optimization and node selection
First term of sj is the dominating one (when l=0) Formulate the problem to a max-min scheme
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4. Hop optimization and node selection (cont’)
Apply previous method and locate the points M nodes are closed to these points We have MH-1 possible paths
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5. Simulations Numerical optimization and Monte-Carlo simulations
L=100 meters Exhaustive: locate the best one from MH-1 possible paths
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5. Simulations (cont’) Numerical optimization and Monte-Carlo simulations Same parameters Capacity raises with the increasing of H H increase analysis performance is better than proposed method
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5. Simulations (cont’) Numerical optimization and Monte-Carlo simulations Maximum capacity we may gain
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6. Conclusion Advantage of our method Disadvantage
More efficient in large networks Feasible to approximate the optimal path by numerical evaluation Disadvantage Results becomes more suboptimal in larger networks We need a good initial condition
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Thank you and Any question?
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