Video scheduling algorithm Ben-Gurion University of the Negev Department of communication system engineering Video scheduling algorithm in OFDMA systems Supervisors: Dr. Shlomo Greenberg Mr. Pavel Babich Oded Sonin Tomer Lichtenfeld

Video scheduling algorithm in OFDMA systems Project goal Finding a video scheduling algorithm for OFDMA systems that will provide high network bandwidth while supporting good video quality for the users. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems Orthogonal Frequency Division Multiple Access (OFDMA) is a multi-user version of the popular OFDM digital modulation scheme. FDM OFDM Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems OFDMA (cont.) Multiple access is achieved by assigning subsets of subcarriers to individual users. This allows simultaneous low data rate transmission from several users. OFDMA Channels assignment example Pilot Sub carriers User 1 Sub carriers User 2 Sub carriers Frequency Guard band Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems MPEG MPEG technology uses differential frame compression. A loss of one packet can result a loss of Group Of Pictures (GOP). MPEG GOP Structure Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The Scheduling problem Assigning resources to users in a way that maximizes the system performance. In our case, providing a scheduling algorithm that will maximize the network performance in terms of bandwidth and video performance. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm Priority Allocation Assignment Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 1. Priority The algorithm is priority based. The bit rate for each user is proportional to his priority which is determined in real time by important criteria. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 1. Priority P(i) is packet number i in the user’s buffer. More important video frames give the user higher priority. More urgent video frames give the user higher priority. Larger packets give the user higher priority. Priority Packet Type 8 I 5 P0 4 P1 3 P2 2 P3 1 B For each packet in the user buffer. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 1. Priority 2. Allocation 3. Assignment Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 2. Allocation The rate for each user is calculated according to the user priority and the estimation of the total bit rate in the network. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 2. Allocation T_B_E - Total bit rate estimation. Estimation_Factor – a dynamic variable, updated according to each assignment and the previous assignment. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 1. Priority 2. Allocation 3. Assignment Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 3. Assignment The problem is assigning the sub-carriers to the users in a way that will maximize bandwidth while supplying each user his necessary bit rate. We use an algorithm from graph theory called Min Cost Flow, traditionally used to minimize cost in a flow network. We translate our problem to a minimal cost flow problem in a graph. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The proposed algorithm 3. Assignment: Min Cost Flow The links are: Start  users Users  channels Channel  Target The nodes are: Users Channels Start Target User 1 User 2 User N Channel M Channel 1 Channel 2 S T להוסיף קיבולות ומשקולות Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The simulation We simulate a wireless OFDMA network base station, transmitting real time encoded MPEG video streams to multiple users. We use MATLAB code to simulate the channel conditions and packet transmission. The proposed algorithm is used to dynamically assign the OFDMA channels to the users. We gather statistics about the performance of the algorithm and compare them with other scheduling algorithms performances. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems Results The algorithm will be measured by two parameters: System throughput- amount of bits transmitted successfully by the base station to the receiving terminals in the cell. Application QOS- percentage of unusable packets received by the terminals. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems Preliminary result The increase in application QoS is caused by the new priority function. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems Preliminary result The increase in system throughput is caused by the new assignment algorithm. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems Further expected research We expect to improve the preliminary results due to improvement of the assignment algorithm and the priority function. Video scheduling algorithm in OFDMA systems

Video scheduling algorithm in OFDMA systems The end Video scheduling algorithm in OFDMA systems