Video Streaming Transmission Over Multi-channel
Multi-path Wireless Mesh Networks
Authors:
Guojun Shui, Shuqun Shen
Speaker :吳靖緯 MA0G0101
2008. WiCOM '08. 4th International Conference on
Wireless Communications, Networking and Mobile Computing
On page(s): 1 - 4, Oct. 2008
2012.02.17
Outline
• Introduction
• Multi-channel multi-path routing
• Performance evaluations
• Conclusion
2
Introduction
• Transmitting real-time video streaming requires
bandwidth, low delay jitter, and low error-rate.
high
• 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 MMDSR 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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