Wireless Token Ring Protocol WTRP A Medium Access Control Protocol for QoS Aware Wireless Networks

1
Wireless Token Ring Protocol (WTRP)A Medium
Access Control Protocol for QoS Aware Wireless
Networks
Mustafa Ergen, Duke Lee, Ruchira Datta, Jeff Ko,
Roberto Attias, Anuj Puri, Raja Sengupta,
Starvros Tripakis, and Pravin Variaya
2
Automated Vehicle Platoon

• Real-time safety critical control over ad-hoc
  network
• Vehicles transmit control data in round robin
  every 20 ms
• Wireless Quality of Service

3
Merge Lane

• Distributed solution
• Need wireless QOS
• Admission control

4
Motivations for WTRP

• Quality of service (real time applications)
• Distributed solution (robust against a single
  node failure)
• Flexible topology (token ring can be created with
  Pico cells)
• Safety critical applications (need fast recovery
  from failure)
• No need for clock synchronization (compared to
  TDMA)
• Partial connectivity (hidden terminal problem)

5
Motivations for WTRP

• Quality of service (real time applications)
• Distributed solution (robust against a single
  node failure)
• Flexible topology (token ring can be created with
  Pico cells)
• Safety critical applications (need fast recovery
  from failure)
• No need for clock synchronization (compared to
  TDMA)
• Works on partial connectivity (no hidden terminal
  problem)

6
Motivations for WTRP

• Quality of service (real time applications)
• Distributed solution (robust against a single
  node failure)
• Flexible topology (token ring can be created with
  Pico cells)
• Safety critical applications (need fast recovery
  from failure)
• No need for clock synchronization (compared to
  TDMA)
• Works on partial connectivity (no hidden terminal
  problem)

centralized (802.11 PCF, Bluetooth)
distributed (token ring)
7
Motivations for WTRP

• Quality of service (real time applications)
• Distributed solution (robust against a single
  node failure)
• Flexible topology (token ring can be created with
  Pico cells)
• Safety critical applications (need fast recovery
  from failure)
• No need for clock synchronization (compared to
  TDMA)
• Works on partial connectivity (no hidden terminal
  problem)

1
4
3
1
2
TDMA
8
Motivations for WTRP

• Quality of service (real time applications)
• Distributed solution (robust against a single
  node failure)
• Flexible topology (token ring can be created with
  Pico cells)
• Safety critical applications (need fast recovery
  from failure)
• No need for clock synchronization (compared to
  TDMA)
• Works on partial connectivity (no hidden terminal
  problem)

9
Additional Challenges From Wireless Medium

• Partial connectivity (unable to hear all nodes in
  a ring)
• Support for multiple rings
• Self-managed admission control
• Frequent packet loss, corruption

10
Solutions Connectivity Table

• Each node builds and updates connectivity table
  that contains information of all stations in its
  reception range, and transmission order of the
  nodes in its ring

11
Solutions Connectivity Table

• Each node builds and updates connectivity table
  that contains information of all stations in its
  reception range, and transmission order of the
  nodes in its ring

12
Ring Recovery

• B fails or moves out of range.
• A tries to transmit to its successor (B) a
  specified number of tries and determine that
  communication link to B is bad.

C
A
B
13
Solutions Unique Ring Address

• Each ring has unique ring id based on unique MAC
  address of one of the stations of the ring.

14
Solutions Unique Priority of Token

• Based on ring address and generation sequence
  number pair.
• Station only accept token that has higher
  priority than the last token that the station has
  accepted.

ring address
generation sequence

15
Token Recovery (Multiple Tokens Resolution)
1
1
2
2
1
1
6
6
16
Token Recovery (Multiple Tokens Resolution)
2
2
1
2
1
6
6
6
17
Token Recovery (Multiple Tokens Resolution)
2
2
2
6
6
1
6
6
18
Token Recovery (Multiple Tokens Resolution)
6
6
2
6
2
2
6
6

• At next step
• Delete token with generation sequence number 2
  since the next node has seen token with
  generation sequence number 6

19
Token Recovery (Multiple Tokens Resolution)
6
6
6
6
2
6
6
20
Token Recovery (Multiple Tokens Resolution)
6
6
6
6
6
6
6
21
Token Recovery (Multiple Tokens Resolution)
6
6
6
6
6
7
7
Token refreshed by owner
22
Token Recovery (Multiple Tokens Resolution)
6
6
6
6
7
7
7
23
Token Recovery (Ring Address Resolution)
6
6
6
6
6
6
7
24
Token Recovery (Ring Address Resolution)
6
6
6
6
8
7
8
This node detects that the owner is down and
claims the token
25
Token Recovery (Ring Address Resolution)
6
6
8
8
6
8
7
26
Token Recovery (Ring Address Resolution)
8
8
6
8
6
8
7
27
QOS Interface
High Priority Applications (6)
Low Priority Applications (6,3)
Wireless Token Ring Protocol (10)
28
QOS Interface
High Priority Applications (6)
Low Priority Applications (6,3)
Wireless Token Ring Protocol (4)
29
QOS Interface
High Priority Applications (6)
Low Priority Applications (6,3)
Wireless Token Ring Protocol (4)
30
QOS Interface
High Priority Applications (6)
Low Priority Applications (6,3)
Wireless Token Ring Protocol (1)
31
WTRP Deliverables (2001)
http//wow.eecs.berkeley.edu
32
UDP Video Streaming
33
Simulation Front End
34
Token Rotation Time Vs. Rotation
A
3
A
A
1
2
B
C
B
B
C
C
35
Fairness
36
Throughput Comparison With 802.11 DCF
37
Conclusions

• The wireless token ring protocol (WTRP) is a
  medium access control protocol for wireless
  networks in mission critical systems.
• It supports quality of service in terms of
  bounded latency and reserved bandwidth.
• WTRP is efficient in the sense that it reduces
  the number of retransmissions due to collisions.
  
• It is fair in the sense that each station takes a
  turn to transmit and is forced to give up the
  right to transmit after transmitting for a
  specified amount of time.
• It is a distributed protocol that supports many
  topologies since not all stations need to be
  connected to each other or to a central station.
  
• It can be used with an admission control agent
  for bandwidth or latency reservations.
• WTRP is robust against single node failure.
  WTRP is designed to recover gracefully from
  multiple simultaneous faults.

38
Conclusions

• The wireless token ring protocol (WTRP) is a
  medium access control protocol for wireless
  networks in mission critical systems.
• It supports quality of service in terms of
  bounded latency and reserved bandwidth.
• WTRP is efficient in the sense that it reduces
  the number of retransmissions due to collisions.
  
• It is fair in the sense that each station takes a
  turn to transmit and is forced to give up the
  right to transmit after transmitting for a
  specified amount of time.
• It is a distributed protocol that supports many
  topologies since not all stations need to be
  connected to each other or to a central station.
  
• It can be used with an admission control agent
  for bandwidth or latency reservations.
• WTRP is robust against single node failure.
  WTRP is designed to recover gracefully from
  multiple simultaneous faults.

39
Conclusions

• The wireless token ring protocol (WTRP) is a
  medium access control protocol for wireless
  networks in mission critical systems.
• It supports quality of service in terms of
  bounded latency and reserved bandwidth.
• WTRP is efficient in the sense that it reduces
  the number of retransmissions due to collisions.
  
• It is fair in the sense that each station takes a
  turn to transmit and is forced to give up the
  right to transmit after transmitting for a
  specified amount of time.
• It is a distributed protocol that supports many
  topologies since not all stations need to be
  connected to each other or to a central station.
  
• It can be used with an admission control agent
  for bandwidth or latency reservations.
• WTRP is robust against single node failure.
  WTRP is designed to recover gracefully from
  multiple simultaneous faults.

40
Conclusions

• The wireless token ring protocol (WTRP) is a
  medium access control protocol for wireless
  networks in mission critical systems.
• It supports quality of service in terms of
  bounded latency and reserved bandwidth.
• WTRP is efficient in the sense that it reduces
  the number of retransmissions due to collisions.
  
• It is fair in the sense that each station takes a
  turn to transmit and is forced to give up the
  right to transmit after transmitting for a
  specified amount of time.
• It is a distributed protocol that supports many
  topologies since not all stations need to be
  connected to each other or to a central station.
  
• It can be used with an admission control agent
  for bandwidth or latency reservations.
• WTRP is robust against single node failure.
  WTRP is designed to recover gracefully from
  multiple simultaneous faults.

41
Conclusions

• The wireless token ring protocol (WTRP) is a
  medium access control protocol for wireless
  networks in mission critical systems.
• It supports quality of service in terms of
  bounded latency and reserved bandwidth.
• WTRP is efficient in the sense that it reduces
  the number of retransmissions due to collisions.
  
• It is fair in the sense that each station takes a
  turn to transmit and is forced to give up the
  right to transmit after transmitting for a
  specified amount of time.
• It is a distributed protocol that supports many
  topologies since not all stations need to be
  connected to each other or to a central station.
  
• It can be used with an admission control agent
  for bandwidth or latency reservations.
• WTRP is robust against single node failure.
  WTRP is designed to recover gracefully from
  multiple simultaneous faults.

42
Conclusions

• The wireless token ring protocol (WTRP) is a
  medium access control protocol for wireless
  networks in mission critical systems.
• It supports quality of service in terms of
  bounded latency and reserved bandwidth.
• WTRP is efficient in the sense that it reduces
  the number of retransmissions due to collisions.
  
• It is fair in the sense that each station takes a
  turn to transmit and is forced to give up the
  right to transmit after transmitting for a
  specified amount of time.
• It is a distributed protocol that supports many
  topologies since not all stations need to be
  connected to each other or to a central station.
  
• It can be used with an admission control agent
  for bandwidth or latency reservations.
• WTRP is robust against single node failure.
  WTRP is designed to recover gracefully from
  multiple simultaneous faults.

43
Conclusions

• The wireless token ring protocol (WTRP) is a
  medium access control protocol for wireless
  networks in mission critical systems.
• It supports quality of service in terms of
  bounded latency and reserved bandwidth.
• WTRP is efficient in the sense that it reduces
  the number of retransmissions due to collisions.
  
• It is fair in the sense that each station takes a
  turn to transmit and is forced to give up the
  right to transmit after transmitting for a
  specified amount of time.
• It is a distributed protocol that supports many
  topologies since not all stations need to be
  connected to each other or to a central station.
  
• It can be used with an admission control agent
  for bandwidth or latency reservations.
• WTRP is robust against single node failure.
  WTRP is designed to recover gracefully from
  multiple simultaneous faults.