Murat Ozyurt* Seckin Ulug Tuna Tugcu Department of Computer - PowerPoint PPT Presentation

Murat Ozyurt* Seckin Ulug Tuna Tugcu Department of Computer Engineering Bogazici University presented by Seckin Ulug M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 Problem Definition ◦ Alternative Solutions  Proposed Solution ◦ Worst-Case Problem  Simulation & Results ◦ Simulation Setup ◦ Evaluation of Results  Conclusion M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 A user’s channel quality may enforce the use of a low capacity modulation ◦ Physical proximity does not necessarily mean connection with high-data rate modulation  Users have to use different modulation schemes according to their available signal quality  In which modulation should the IPTV channels be broadcast? M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 Broadcast a requested IPTV channel for each type of modulation once. + Every user gets the service at maximum available connection quality. - Capacity insufficient to broadcast an IPTV channel more than once  Broadcast a requested IPTV channel once, using the highest applicable modulation (i.e., using a robust modulation) for everyone + Every user receives the transmission at the same time period. + No retransmission of the same channel for each type of modulation. - Even good quality connections have to use the chosen low capacity modulation. M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 Mesh mode operation enables relaying over a subscriber station (called the one-hop node) ◦ Benefit from space diversity to relay simultaneously  Subscriber stations (called the two-hop nodes) who suffer bad channel conditions due to physical factors may receive service via relaying M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 Scheduling works in the following order: 1. The base station transmits frames for all requested IPTV channels 2. One-hop nodes simultaneously transmit frames of two-hop nodes that can receive data without collision with other concurrent transmissions. 3. One-hop nodes sequentially transmit frames of remaining two- hop nodes that can not be scheduled to same slot with any other transmission without collision 1/ M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 The worst case occurs when ◦ All subscribers are watching different IPTV channels ◦ No parallel transmission from one-hop nodes to two-hop nodes is possible All distributed transmissions have to be made sequentially   The total duration of a single burst of requested IPTV channels (K) in the worst case is calculated as follows: where F is the framelength of a single burst of an IPTV channel in terms of bits, ◦ O Total number of one-hop nodes in the network, T is the total number of two-hop nodes in the network ◦ C BS and C i are the capacity of the air link modulation in terms of bits per second for BS to one-hop nodes and one-hop ◦ nodes to two-hop nodes, respectively. C BS and C i are taken equal in our solution. M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 Developed in JAVA platform  300 Mbps available air-link capacity (IEEE 802.16m)  6 Mbps bandwidth requirement for each IPTV channel  Simulations of ◦ 3 hours long ◦ All combinations of  Initial number of one-hop nodes: 10,30,50,70,90  Initial number of two-hop nodes: 10,30,50,70,90 ◦ 100 repetitions for each setup M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

Parameter Value Description Channel Count 1000 Number of IPTV channels Traffic requirement of a TV channel in terms of megabits-per- Channel Bandwidth 6 second Framelength of a single burst of an IPTV channel in terms of Frame Length 300 kbits Simulation Duration 180 Simulation length in minutes One-Hop Nodes 10,30,50,70,90 Initial number of one-hop nodes Two-Hop Nodes 10,30,50,70,90 Initial number of two-hop nodes. Probability of a New Node 0.03 Probability of joining a new node, each second. Probability of Leaving 0.03 Probability of a node to leave, each second. Two-hop nodes are transferred to another one-hop node Probability of Finding a 0.10 according to this value, if existing one-hop node leaves the Transfer Node network. Probability of Two-Hop Probability of Two-Hop Connection 0.30 Probability of a new 0.30 Connection node to request relay. Probability of Changing Nodes change their current IPTV channels with this probability 0.06 Channel every second Probability of Collision At Two-hop nodes receive signals from multiple one-hop nodes 0.10 Two-Hop Nodes with this probability M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 Scenarios: Up to 70x10, 50x50 or 30x70 one-hop and two- hop node combinations network may operate with air-link utilization below ~85%.  More nodes cause fully-utilized network, yet we may still achieve reasonable inter-frame delay values M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Average ge Utiliza zati tion on of air ir-link Bogazici University, presented at MSWiM ’ 10

 Delays up to 100 ms between two consecutive visual frames of an IPTV channel can not be perceived by humans  We considered inter-frame delays up to 50 milliseconds as tolerable in our simulations Two-Ho Hop p Nodes One-Hop op Nodes 10 30 50 70 90 3/4 2/18 9/15 16/29 22/44 10 1/14 8/10 15/22 20/33 29/49 30 8/8 16/19 27/34 33/46 42/61 61 50 19/19 27/31 37/44 49/61 61 60/77 77 70 34/33 41/45 57/63 63 63/74 74 80/95 95 90 Average ge Inter-frame me Delay in Millisecon onds ds values shown as one-hop op delay y / two-hop op delay M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 In case of scenario with initially 10 one-hop nodes and 50 two-hop nodes, which under-utilizes bandwidth (~60%) ◦ No delay for ~84% of the frames in the first hop and ~63% of the frames in the second hop  ◦ Tolerable delays (below 50 ms) for ~99% of the frames in the first hop and ~97% of the frames in the second hop  Percenta tage ge Distribu buti tion of Delayed d Frames (One-hop p Nodes by Two-hop op Nodes vs vs Delay (msec)) )) M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 In case of scenario with initially 90 one-hop nodes and 50 two-hop nodes, which utilizes bandwidth fully ◦ Tolerable delays (below 50 ms) for ~73% of the frames in the first hop and ~71% of the frames in the second hop  ◦ Intolerable delays (above 50 ms) for ~27% of the frames in the first hop and ~29% of the frames in the second hop  Percenta tage ge Distribu buti tion of Delayed d Frames (One-hop p Nodes by Two-hop op Nodes vs vs Delay (msec)) )) M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

 Broadcasting in classical WiMAX systems is inefficient since the users experience different channel quality ◦ Requires retransmission of the same IPTV channels with different modulations ◦ Transmission using the highest available modulation for everyone  WiMAX mesh mode operation enables us relay transmissions over other subscribers  IPTV broadcasting in WiMAX Mesh mode operation has been improved to allow for more efficient broadcasting ◦ We propose parallel relaying by benefiting from space diversity M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10

Questions??? M. Ozyurt, S. Ulug, T. Tugcu, Department of Computer Engineering, Bogazici University, presented at MSWiM ’ 10