Video Streaming Transmission Over Multi-channelMulti-path Wireless Mesh Networks

2012.02.17

Speaker : 吳靖緯 MA0G0101

2008. WiCOM '08. 4th International Conference onWireless Communications, Networking and Mobile Computing

On page(s): 1 - 4, Oct. 2008

Authors:Guojun Shui, Shuqun Shen

Outline

• Introduction

• Multi-channel multi-path routing

• Performance evaluations

• Conclusion

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Introduction

• Transmitting real-time video streaming requires high bandwidth, low delay jitter, and low error-rate.

• Achieving each of these requirements in a WMNs is challenging itself, considering the limited bandwidth, high delay jitter, and the high bit error-rates of wireless medium.

• All these problems could be caused by both the nature of wireless medium and high route breakages.

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Introduction

• Single-channel protocols have a single common channel shared by all nodes.

• Collisions always occur when two or more nodes transmit simultaneously.

• Comparing with single-channel protocols, utilization of multichannel technology, which allows simultaneous transmissions on different channels, increasing average network throughput and decreasing the propagation delay.

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Introduction

• In this paper, we proposed Multi-channel Multi-path Routing DSR(MM-DSR) protocols that builds two disjoint paths.

• Real-time video streaming can be divided into two sub-streams and each of the sub-stream is transmitted through one of these two paths to avoid congestion.

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Multi-channel multi-path routing

• When the source needs a route to the destination but no route information is found in cache, it floods the ROUTE REQUEST (RREQ) messages to the entire network.

• The destination node then sends ROUTE REPLY (RREP) messages responding to the RREQ back to the source node.

• The source node selects multiple routes based on given metrics.

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Multi-channel multi-path routing

A. Route Discovery

• The source node will flood the RREQ messages in order to find paths to the destination.

• Each RREQ identifies the source and destination of the route discovery, which contains unique request identification (ID).

• When another node receives this RREQ and is the destination of the route discovery, it returns an RREP to the source of the route discovery.

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Multi-channel multi-path routing

• It will check if this RREQ is duplicated or not by the ID.

• If it is not the duplicate, it appends its ID and rebroadcasts the packet.

• Otherwise, it will discard this duplicate RREQ.

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Multi-channel multi-path routing

• An example of a MM-DSR routing protocol is shown in Figure 1, where the source node will select the two best routes from the route cache for data transmission at bands P1 and P2.

• In this protocol, all the nodes can listen to both frequency bands P1 and P2.

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Multi-channel multi-path routing

B. Route Selection Method

• In order to measure the performance of each route for the selection process, we define the following metrics:

(1) Hop count

(2) Delay of route

(3) Number of joint nodes between two routes

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Multi-channel multi-path routing

• In the route selection process, the source node will try to find the two best routes based on the above metrics.

• First, a route with the smallest hop count has the highest priority.

• If two or more routes have the same hop count, then delay of route is used to select the route with the smaller joint nodes.

• The next step is choosing the second best route amongst the remaining routes.

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Multi-channel multi-path routing

C. Route Maintenance

• In MM-DSR, when one node detects a broken link, it will send the ROUTE ERROR (RERR) message.

• Once the source node receives the RRER message, it will remove every route entry in the route cache, which uses the broken link.

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Performance evaluations

A. Multiple Description Coding

• Multiple description coding (MDC) is a technique that generates multiple equally important descriptions.

• In a multiple description (MD) coder known as multiple description motion compensation (MDMC) is employed.

• With this coder, two descriptions are generated by sending even pictures as one description and odd pictures as the other.

• When both descriptions are received, the decoder can reconstruct a picture.

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Performance evaluations

B. Simulation Environment

• Our simulation modeled a wireless mesh network of 10 static Mesh Routers placed in a rectangular field of 400×1500 m2.

• Each node has a radio propagation range of 250 meters and channel capacity was 2Mb/s.

• Each run executed for 300 seconds of simulation time.

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Performance evaluations

C. Results and Analysis

• In the simulations, we use the “Packet Success Delivery Percentage” metric to evaluate the performance.

• Packet Success Delivery Percentage:

It is the ratio between the number of packets received by the destination nodes to the number of packets sent by the source nodes.

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Performance evaluations

• Figure 2 shows the Packet Success Delivery Percentage comparison between two protocols in WMNs, and the sizes of packet was 300, 350, 400, 450, and 500 bytes respectively.

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Performance evaluations

• As shown in Figure 3, for a packet size of 500 bytes, the MM-DSR results, compared with SMR, verify the profound effect that the elimination of inter-path interference can have on the multiple-path routing performance.

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Performance evaluations

• Figure 4 shows the average peak signal-to-noise ratio (PSNR) quality of video signals at the destination node for 150 frames.

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Performance evaluations

• In these experiments, MDMC is used to generate the video packets.

• The source node then transmits them to the destination node using MM-DSR and SMR protocols respectively.

• Such a significant gain is mainly due to the fact that MM-DSR improves the link connectivity and eliminates interference under wireless conditions.

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