ICACT20210196 Slide.16
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This is end of presentation
Thank you for listening
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ICACT20210196 Slide.15
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Left figure shows the simulation result for measuring the latency of the scenario by comparing WCETT and RBMRP.
WCETT periodically measures all link quality to the path and updates routing metrics of the path to detect and respond to changes in the network.
The way to measure the quality of a link is to exchange the probe message.
However, in the multi-radio multi-channel environment, the node should transmit the probe message to existing all channels to measure the quality of all links. Then, when the probe message is transmitted by channel, channel switching overhead occurs.
In our environment, 6 channel switching occurs at the time of one probe message exchange. For this reason, the latency of WCETT fluctuates periodically. By contrast, RBMRP also detects and responds to changes in the network by simply measuring RSSI. Measuring RSSI does not incur any extra cost. Therefore, RBMRP is superior to WCETT in terms of low latency.
Right figure shows the simulation result for measuring throughput by comparing WCETT and RBMRP.
This result indicates that the throughput of RBMRP is higher than WCETT because the throughput of WCETT is rapidly decreased when the probe message is exchanged.
But RBMRP doesn¡¯t need a extra cost.
WCETT is famous for its efficient path with low latency and high throughput.
Then, RBMRP, which does not require a probe message, also shows better performance in the throughput part.
In terms of latency, however, it shows that RBMRP is more efficient than WCETT, which periodically generates probe messages.
That means, RBMRP does not require an extra cost for metric measurements, but it can discover a path that has similar performance to WCETT with an overhead for metric measurements.
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ICACT20210196 Slide.14
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This is our simulation setup table.
In the scenario, we consider WAVE nodes as smart poles and a root node as Gateway pole, which means a mesh node has streaming data needed to be processed, so it transmits the data to the GW in the uplink path.
As the simulation starts, node 12 transmits data traffic to the gateway node, and after 20 seconds node 10 transmits data traffic to the gateway. Node 10 stops transmitting data traffic at 50 seconds.
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ICACT20210196 Slide.13
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Next chapter is performance Evaluation
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ICACT20210196 Slide.12
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In detail, each node scans SCH 1 through SCH 6 and allocates the channel with the lowest RSSI value as the receiving channel. To avoid overlapping of channels with nearby nodes, the node generates a noise through the selected receiving channel until channel allocation of other nodes is completed. After that, control messages of RBMRP are transmitted in the CCH period. The information of the node including receiving channel is delivered by a Hello message. And the route discovery to the gateway starts with PREQ due to RANN. When the PREQ is transmitted, each node adds RSSI of the receiving channel for downlink routing and uplink routing. The node received PREQ selects the downlink route to the best path with the least RSSI. When the gateway receives PREQ message, it compares the uplink metrics and transmits the PREP to the best path with the least RSSI. Like downlink routing, the node received PREP add the uplink route to the gateway. And through the Hello message, the RSSI of the neighbor node and the routing metric to the gateway is updated. If the updated routing metric exceeds the threshold, the node sends PERR and re-discover the route to the gateway
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ICACT20210196 Slide.11
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Next contribution is Routing Protocol.
RBMRP is designed by modifying the HWMP to suit for multi-channel and multi-radio environment.
So I modified Hello message and PREQ msg and PREP message.
The Hello message is delivered to the sending interface during the CCH period, but it contains the receiving channel information.
When a node transmits data to another node, it transmits the data after switching the sending interface channel to the destination node¡¯s receiving channel.
That information could be known through the Hello message.
And after routing, routing metrics are updated through Hello message.
And a PREQ message is broadcasted including two metrics for uplink routing and downlink routing in a CCH interval.
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ICACT20210196 Slide.10
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This is Channel Allocation Algorithm.
Node measures RSSI during T on each 6 SCH.
And select the channel that have lowest Cumulative RSS as receiving channel.
To avoid overlapping of channels with nearby nodes, the node generate noise until all neighbor nodes allocate the channel.
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ICACT20210196 Slide.09
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RBMRP utilizes RSSI information for channel allocation.
When there is no packet destined for a node, the RSSI is treated as noise. To minimize transmission collision, we use the RSSI to disjointly allocate the channel.
For efficient channel allocation, a node proceeds channel scanning by collecting Cumulative-RSSI for each SCH channel to select the optimal receiving channel.
Through the C-RSS value, a node can determine the degree of noise for each channel.
When the measurement is completed for all channels, the channel with the lowest C-RSS is allocated to the receiving channel.
and the node to which the channel is assigned generates noise through the selected receiving channel until all neighbor nodes allocate the channel.
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ICACT20210196 Slide.08
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Before introducing the proposed scheme, I will describe our assumptions about the targeting environment.
We use 7 channels according to IEEE 1609.4 standard and two radio interfaces.
We manage the radio interface by setting one interface as the sending interface and another interface as receiving interface to minimize channel switching overhead.
To minimize channel switching overhead, we set the channel of the receiving interface is fixed and the sending interface channel is switchable according to the receiving interface¡¯s channel.
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ICACT20210196 Slide.07
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There are 2 contributions in proposed scheme.
Channel allocation and routing protocol
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ICACT20210196 Slide.06
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Existing metrics such as Distance Vector and Air Link Metric and WCETT are not suitable for MRMC environments.
These are not for multi radio, multi channel environment. Also WCETT need to exchange prove messages to calculate metric. In MRMC environment, periodic exchanging through each channel that incurs huge overhead due to the channel switch delay.
So we proposed a RSSI-based mesh routing protocol RBMRP IEEE 802.11p/WAVE based smart pole networks.
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ICACT20210196 Slide.05
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To support a smart pole mesh system,
a low latency wireless communication technology for V2I and I2I is essential.
IEEE 802.11p is the standard for a vehicular wireless network that provides MAC and PHY specifications to support Wireless Access in Vehicular Environment that is called WAVE.
Wireless Mesh Network technology capable of operating in that standard is required.
So there is an IEEE 802.11s for WLAN based wireless mesh network.
To operate IEEE802.11s based HWMP protocol on the IEEE 802.11p/WAVE network,
it is necessary to modify the protocol by considering the IEEE 1609 operation and multi-radio operation for multi-hop communication.
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ICACT20210196 Slide.04
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Have you ever heard about ITS?
ITS is Intelligent Transportation System.
So through this system, We can make road safe, prevent accidents and monitor road condition.
For example, there was a traffic accident on the road. Nearby other cars and smart street pole that equipped various IoT sensor like monitoring camera, they transmit Accident information to other device and ITS center. Then we can respond to an accident faster. This leads to prevention of additional accidents. Even artificial intelligence computing unit can predict accidents by collaborating with nearby vehicle and other smart poles.
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ICACT20210196 Slide.03
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Let¡¯s start Introduction.
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ICACT20210196 Slide.02
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The presentation has three parts. First introduction
And Second proposed scheme
and last performance evaluation
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ICACT20210196 Slide.01
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Hello! Everyone. I¡¯m JongYoung Choi. And I will give a short presentation about the paper.
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