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 xli@binghamton.edu

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

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.

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

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

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

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

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)

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)

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

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

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

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

5. Simulations Numerical optimization and Monte-Carlo simulations L=100 meters Exhaustive: locate the best one from MH-1 possible paths

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

5. Simulations (cont’) Numerical optimization and Monte-Carlo simulations Maximum capacity we may gain

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

Thank you and Any question?