Cross Layer Architecture for Maintaining QoS in Multimedia Applications

Multimedia applications requires certain QoS to meet certain functionality.QoS requirements include bandwidth guarantees and temporal guarantees. In this paper, we propose a novel method that uses a cross layer architecture in which information from Application layer is used with UDPLite in Transport layer and Active Queue Management (AQM) with SiViRED in Network Layer with modified dynamic mapping in MAC layer that guarantees 14% increase in Peak signal to Noise ratio (PSR) and 40% decrease in delay compared to conventional methods.


INTRODUCTION
In MANETs, Routers implement active queue Mobile Adhoc Networks (MANeTs) isself- [1] and provide service differentiation to the traffic configuring and infrastructure less network of mobile according to pre-assigned service classes and drop devices connected without wires.MANETs are complex priorities carried in the packet header. in nature as each device is free to move and can link with In [2] Floyd et al, the adaptive RED or active RED other devices frequently hence wireless medium is used.
(ARED) algorithminfers whether to make RED more or less All these attributes make MANET more intricate entity to aggressive based on the observation of the average deal with.Moreover transmitting multimedia applications queue length.If the average queue length oscillates over MANETs maintaining a QoS is a big challenge.
around min threshold then early detection is too The Challenge could be overcome by two methods 1) aggressive.On the other hand if the average queue length Video Compression 2) Application layer QoS control oscillates around max threshold then early detection is technique.Video Compression techniques are used to being too conservative.So the ARED active Queue reduce the amount of data size so that lesser amounts of management algorithm does not control the video traffic data are transmitted in the bandwidth scarce Networks in MANETs properly.and the size of memory used is reduced.Application-NRED is an extension of the original RED scheme.K. Layer QoS control techniques are used to reduce the Xu et al [3] assumed that each node keeps estimating the transmission delays and the packet loss that occur in the size of its neighborhood queue (distributed queue).Network.
Another assumption is once the queue size exceeds a Rest of the article is organized as follows 1) Related certain threshold, an overall drop probability is computed works 2) Proposed System 3) Simulation results and by the algorithm of NRED and this overall drop Discussion.
probability is propagated to all the nodes in the Related Works: Especially in MANETs, packet loss dropping the packets.But in the MANETS the nodes in results in increased overhead in terms of energy wasted the topology would not cooperate that much because the to forward a packet which was dropped, additional energy topology will change very frequently.So cooperation required to retransmit this packet.Active Queue cannot be expected.The second Point is nodes will send Management (AQM) has been a solution to the global neighborhood congestion notification Packets to the synchronization problem in wired networks.neighborhood nodes again which is time consuming and management schemes, such as RED with In and Out (RIO) neighborhood nodes.The neighborhood nodes starts those packets will be utilizing the channel bandwidth preceding I -frame and B-frame contain data that during the congestion resulting in high delay.Thirdly no have changed from both preceding and following frames.priority has been given to the packets so all the packets Thus I packet has high priority than P packet and P packet will be given equal preference while dropping the packets has more priority than B -packet frame.The marking of during congestion.So using NRED algorithm with AQM drop differentiation of video packets takes place at video for video streaming in MANETs is not beneficial.
source based on the type of MPEG frame.Sentini et al. [4] proposed a cross-layer architecture The generated video information at the Application that relied on a Data Partitioning (DP) technique at the Layer is mapped to the Type of Service (TOS) of DS field Application layer and an appropriate QoS mapping at the in IP header.The TOS field contains the pre-marked video 802.11e-basedMAC Layer.Each data partition was priority information.I-frame packets are marked with the mapped statically into MAC layer [5,6].
lowest drop probability and P-frame packets are marked Zeadally et al. [7], proposed a cross-layer with a medium drop probability, B-frame packets are mapping algorithm to improve the quality of marked with the highest drop probability.According to transmission of H.264 video stream over IEEE 802.11e the priority information and service differentiation defined based wireless networks.Cross-layer design involves the by the, SiVIREDAQM algorithm in edge routers the video mapping of H.264 video slices (packets) to appropriate traffic is handled.access categories of IEEE 802.11e rendering to When the queue gets accumulated in edge router significance of its information.
with video packets and transcends a given threshold, the In [8] Naveen Chilamkurti et al proposed dynamic SiVIRED begins to drop packets following the specified mapping algorithm in which video packets are dynamically drop probability parameters.Significant Video Information mapped to the appropriate Access Category based on the Based Random Early Detection (SiVIRED), unites the factors namely the significance of the video data and the capabilities of the RED algorithm with video Precedence network traffic load.By exploiting the dynamic mapping (I packet>P packet>B packet).This combination affords approach, the transmissions of essential video data are preferential traffic handling for higher priority video prioritized thereby improving the queue space utilization.
packets and lower priority video packets than In the above two approaches [7, 8] inter-packet delay conventional traffic.It can discriminate and reject lower is very high.In proposed system, a cross layer priority traffic when the queue begins to get overfilled.architecture in which an Active Queue Management for If the number of packets are more than the minimum diffserv in MANETs has been designed that uses the threshold then the packets are stored in a queue if it is video significance information gathered from application greater than maximum threshold then the lower priority layer and UDPLite in transport layer, SIVIRED AQM packets are dropped,if the average queue size is between ALGORITHM [9-14] in network layer to avoid congestion, maximum and minimum then arriving packets are stored DYNAMIC MAPPING IN MAC layer to reduce delay and with a drop probability.jitter and to improve the performance of streaming.
The maximum threshold (maxth) parameter value is Proposed System: In proposed system, we combine the (minth) is assigned as 0.6*queue length and maximum RED algorithm with video precedence called as SiViRED dropping probability (Pmax_I) is assigned as 0.016 for I (Significant Video Information Random Early detection) Packet.Maximum threshold parameter (maxth) for P packet -AQM in the Network layer that provides service is assigned as 0.6* queue length and minimum threshold differentiation based on the pre-assigned service classes (minth) is assigned as 0.4*queue length and maximum and video packet drop priority specified in packet header.
dropping probability (Pmax_B) is assigned as 0.02.For B This will reduce congestion and decrease delay and jitter packets and maximum threshold parameter(maxth) is when compared to conventional methods.assigned as 0.4* queue length and minimum threshold SiViRED -AQM is implemented in Edge Router.
(minth) is assigned as 0.2*queue length and maximum Edge Router has 3 virtual queues for 3 video frames I dropping probability (Pmax_B) is assigned as 0.03 -packet frame,P-packet frame, B -packet frame.I frame respectively.The weight of queue (w ) is assumed as called as Intra frame is very necessary for more quality 0.002.The packets from the Network layer are sent to the whereas P-frames and B-frames are called as delta frames.
MAC layer.In MAC layer the proposed modified dynamic P-frame -contain only the data that have changed from mapping is used.In modified dynamic mapping the MPEG 4 videos are mapped dynamically to the appropriate category (AC).Loss of B-frame does not affect the video but loss of I-frame would cause all the frames in GOP(Group Of Pictures) to be undecodable.Based on the significance of the video the frame is placed in a appropriate category.The video frames are mapped in to Access Category (AC) queues such as AC [0], AC [1], AC [2] according to the video coding significance Other traffics are assigned to AC [3].
When the MPEG-4 video streams are transmitted as traffic, as per the static mapping algorithm proposed in [1], the I frame will always be mapped to AC [2], while the P frame will be mapped to AC [1] and the B frame will be mapped to AC[0].If the AC [2] queue is empty (which means the video traffic load is light) such a static mapping algorithm will result in unnecessary transmission delays as well as high packet loss if AC [1] and AC [0] are almost full at the same time.To avoid the packet loss andto guarantee the quality of delivered video the proposed mapping algorithm dynamically allocates the video to the most appropriate AC at the MAC layer according to both the significance of video type and the network traffic load.To allocate important video data into higher priority AC queue in 802.11eMAC layer as far as possible, new parameter called Probability-TYPE is introduced so that less important video frame types will be assigned larger probability.Probability-TYPE have been defined for three video frames I,P,B as Prob_I for I frame, Prob_P for P frame and Prob_B as Probability-TYPE for B frame according to its coding significance.The frame which has been mapped to a lower priority queue, the transmission allocating probability of that frame is higher than that of important video frames.As a result, for the MPEG-4 codec the downward mapping probability relationship of these three video frame types is Prob_B > Prob_P > Prob_I.
Furthermore, to support dynamic adaptation to changes in network traffic loads, MAC queue length is used as an indication of the current network traffic load.According to the IEEE 802.11e specification, when MPEG-4 video packets are transmitted over an IEEE 802.11e wireless network, they are placed in AC2 category which has better opportunity to access the channel than lower priority ACs.The tradeoff is, when the video stream increases, this queue rapidly jams and dropping occur.For this reason, the proposed mapping algorithm rearranges most recently received video packets into other available lower priority queues, while the AC2 queue is getting filled.The two threshold parameters, maxth and minth are adopted predicatively to avoid the upcoming congestion by performing queue management in advance.Probability-TYPE will be adapted according to the current queue length and threshold values and the result is a new downward mapping probability, Probability-New.Probability-New is based on four parameters namely math,minth, current queue length and Probability-TYPE.When the Probability-New value is higher, the opportunity for the packet to be mapped into a lower priority queue is greater.The queue length is managed with the help of threshold parameters.The threshold parameters for IPB packets are configured to the percentages of the total number of packets which is assumed as 50 (queue length).The maximum threshold (maxth) parameter value is assigned as 40 and minimum threshold (minth) is assigned as 10.The integrated function in the Cross Layer mapping approach using these parameters is given In this function, when the queue length of AC2 is between maxth and minth, the video packets are mapped to the ACs based on their Probability-Type and the current queue length.The AC2 queue length is taken into account because it has better opportunity to access the channel than other lower priority ACs and if this queue gets filled the video packets will be dropped.

Table 1 :
Simulation Parameters for Udplite and Sivired Algorithm and

Table 2 :
Comparison of Psnr and Delay of Proposed Approach and Other 7. Soni, R., N. Chilamkurti, G. Giambene and S. Zeadally, In the simulation, the proposed SiVIRED method Over Wireless Local Area Networks, International and Modified dynamic mapping algorithm in MAC layer.Symposium on Computer Science and its The video sequenceForeman", is at QCIF format with 400 Applications, CSA, 08: 387-392.frames.8. Naveen, Sherali Zeadally, Robin Soni and Giovanni The above shows that the proposed approach Giambene, 2010.Wireless multimedia delivery over outperforms all the other related approaches in terms of 802.11e with cross-layer o Chilamkurti ptimization Delay.techniques, Springer Multimedia Tools Application, CONCLUSION 9. Gomathi, N., P. Seethalakshmi and Dr. A. Govardhan, The Multi Description Coding along with UDPLite For Multimedia Streaming Over Mobile Adhoc and multipath transport and SiVIRED are proposed to Networks, International Journal on Computer Science enhance the quality of video transmission over Mobile and Engineering, 3(1): 114-126.adhoc Networks.The simulation results show that the 10.Gomathi, N., P. Seethalakshmi, A. Govardhan proposed approach achieves an increase of 14% in Peak N. Gomathi, P. Seethalakshmi and A. Govardhan, Signal to Noise Ratio (PSNR) which is an improvement in 2011.Performance Evaluation of Multimedia PSNR and 40% decrease in delay as compared to the Streaming Over Mobile Adhoc Networks Using conventional methods.Mapping Algorithm, International Journal of wireless