Software Architecture
Application with DECA protocol
DENSO provides the Software Service and the underlying Linux Operating
System (OS). GPS data can be obtained from the API provided by the Software
Service. To transmit and receive data, it can be done using WAVE radio module. An
onboard application can access the internal service directly using API. On the other
hand, an offboard application needs to connect to the Offboard Access Services (OAS)
via Ethernet to grant access to use available services like GPS and radio module.
The offboard application must setup a UDP socket to communicate with OAS.
The OAS is listening to a fixed UDP port number 42000 for a command that is sent
from a host. OAS can support multiple applications from multiple hosts that are
connected to the WSU-5001.
Hardware Architecture
Access Point
Raspberry Pi + Sensors
Ethernet Switch
DENSO WSU-5001
Voltage Step Down Circuit
- 24V to 5V (Switch+Pi)
- 24V to 12V (DENSO+AP)
The DENSO's Wireless Safety Unit (WSU) is a wireless platform designed for
evaluating Intelligent Transportation System (ITS) applications in an automotive
environment. In our experiment, we use WSU model 5001 (WSU-5001). The WSU5001 ports and connectors are shown in the figure above.
DECA Protocol algorithm [1]
This figure shows the algorithm of DECA protocol.
DECA Implementation [2]
For our protocol implementation we chose and did it for onboard application
because of the convenient in deployment. Our application will transmit and receive
data via radio module on IPv4 UDP socket. This figure shows how our application
sends out and receives the message using Radio Interface Services (RIS) API.
This figure shows cross-compiled Makefile for our application. Due to its support
programming language limitation, we implement the application and protocol using C
language. DENSO WSU also cannot compile any programing language into a binary
code itself so we need to do a cross-compiled process on another computer and
deploy the compiled-binary file back to the device.
Installation processes
Communication box was installed at the front of shuttle bus.
GPS
Antenna
Base station and Antenna
Preliminary Experiment
We have preliminarily tested our application in ISEL Laboratory.
- Test DECA protocol
- Test Scenario: One-hop, Two-hops
- Ping pong test: Active 3 nodes simultaneously
Experiment results
1
2
3
4
50.00%
5
6
7
8
9
0.00%
5:00:00
5:30:00
6:00:00
6:30:00
7:00:00
7:30:00
8:00:00
8:30:00
9:00:00
9:30:00
10:00:00
10:30:00
11:00:00
11:30:00
12:00:00
12:30:00
13:00:00
13:30:00
14:00:00
14:30:00
15:00:00
15:30:00
16:00:00
16:30:00
17:00:00
17:30:00
18:00:00
18:30:00
19:00:00
19:30:00
Online Activity Ratio
100.00%
Available 9 nodes (old results)
50%
76 (Line 1)
79 (Line 1)
80 (Line 1)
81 (Line 2)
82 (Line 4)
83 (Line 1)
85 (Line 4)
89 (Line 1)
90 (Line 4)
91 (Line 2)
92 (Line 2)
93 (Line 1)
95 (Line 4)
98 (Line 2)
Available 15 nodes (new results)
Packet Delivery Ratio
100.00%
91.30%
80.22%
80.00%
70.20%
75.00%
50.00%
0.00%
91
92
93
94
95
Maximum number of nodes that were online simultaneously is 5 nodes (old
results).
88 (Line 2)
19:30:00
19:00:00
18:30:00
18:00:00
17:30:00
17:00:00
16:30:00
16:00:00
15:30:00
15:00:00
14:30:00
14:00:00
13:30:00
13:00:00
12:30:00
12:00:00
11:30:00
11:00:00
10:30:00
10:00:00
9:30:00
9:00:00
8:30:00
8:00:00
7:30:00
7:00:00
6:30:00
6:00:00
5:30:00
0%
5:00:00
Online Activity Ratio
100%
Packet Delivery Ratio
100%
83.93%
83.50%
65.52%
65.42%
56.44%
64.17%
57.42%
56.06%
85
89
50%
0%
76
79
81
83
90
92
Maximum number of nodes that were online simultaneously is 8 nodes (new
results).
Reference
[1] Nawut Na Nakorn; Rojviboonchai, K., "DECA: Density-aware reliable broadcasting in vehicular
ad hoc networks," Electrical Engineering/Electronics Computer Telecommunications and
Information Technology (ECTI-CON), 2010 International Conference on , vol., no., pp.598,602,
19-21 May 2010
[2] Pramuanyat, N.; Nakorn, K.N.; Rojviboonchai, K., "Preliminary study of reliable broadcast
protocol on 802.11p public transport testbed," in Electrical Engineering/Electronics, Computer,
Telecommunications and Information Technology (ECTI-CON), 2015 12th International
Conference on , vol., no., pp.1-6, 24-27 June 2015