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

presented by

Seckin Ulug

Murat Ozyurt* Seckin Ulug Tuna Tugcu

Department of Computer Engineering Bogazici University

• 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

• ther

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
• CBS and Ci 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. CBS and Ci 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 Channel Bandwidth 6 Traffic requirement of a TV channel in terms of megabits-per- second Frame Length 300 Framelength of a single burst of an IPTV channel in terms of 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. Probability of Finding a Transfer Node 0.10 Two-hop nodes are transferred to another one-hop node according to this value, if existing one-hop node leaves the network. Probability of Two-Hop Connection 0.30 Probability of Two-Hop Connection 0.30 Probability of a new node to request relay. Probability of Changing Channel 0.06 Nodes change their current IPTV channels with this probability every second Probability of Collision At Two-Hop Nodes 0.10 Two-hop nodes receive signals from multiple one-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

Average ge Utiliza zati tion

• n of air

ir-link

• M. Ozyurt, S. Ulug, T. Tugcu,

Department of Computer Engineering, Bogazici University, presented at MSWiM’10

 Delays up to 100 ms between two consecutive visual frames

• f an IPTV channel can not be perceived by humans

 We considered inter-frame delays up to 50 milliseconds as

tolerable in our simulations

One-Hop

• p

Nodes Two-Ho Hop p Nodes 10 30 50 70 90 10

3/4 2/18 9/15 16/29 22/44

30

1/14 8/10 15/22 20/33 29/49

50

8/8 16/19 27/34 33/46 42/61 61

70

19/19 27/31 37/44 49/61 61 60/77 77

90

34/33 41/45 57/63 63 63/74 74 80/95 95

Average ge Inter-frame me Delay in Millisecon

• nds

ds values shown as one-hop

• p delay

y / two-hop

• p 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

• p 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

• p 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

• ver 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