s Mesh Networks Introduction to Wirelesswireless.ictp.it/wp-content/uploads/2012/02/school... · 2012. 2. 13. · – Example: MeshDynamics MD4000 Compatibility options 1. Use standard

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Introduction to Wireless Mesh Networks • ICTP-ITU/BDT School on Sustainable Wireless ICT Solutions • Miramare, Trieste, Italy, Feb. 14th, 2012. Slide 1

ICTP-ITU/BDT School on Sustainable Wireless ICT Solutions 2012

Introduction to Wireless

Mesh Networks

Andreas J. Kassler [email protected]

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Wireless Mesh Networks Overview

  Wireless Mesh Networks –  Introduction –  Routing –  Channel Assignment Schemes –  Testbeds –  Conclusion

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  Overview Part III –  Dual Radio Meshes –  Multi-Channel Meshes –  Multi-Channel Single Radio –  Multi-Channel Multi Radio –  Routing Metrics for Multi-Channel –  802.11s Aspects

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Dual Radio WLAN Meshes Single-Radio Single-Channel Mesh Throughput

Key issues:  Cannot Tx and

Rx in parallel (single radio)

 More problems due to collisions (hidden nodes) and interference

 Need to serialize reception and transmission

 Reduces capacity

Per MN Capacity=1/N , (N=hops)

P1 P2 P3 P4

Step = 3 Step = 6 Step = 9 Step = 12

Single Radio and Single Channel 12 Steps to send 4 packets

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Dual Radio WLAN Meshes Dual Radio Single-Channel WMNs

  Single Radio Mesh –  Bandwidth sharing of

•  Access Tier •  Backhaul Tier •  External Interference

  Dual-radio mesh –  Client access and backhaul traffic separated on two different Radios

•  Different frequencies (e.g. 2.4 GHz 802.11b and 5 GHz 802.11a) –  Bandwidth sharing of

•  Backhaul Tier •  External Interference

–  Local access does not affect backhaul traffic –  BUT: Wireless Backhaul still shared in 802.11a band

•  Reduced system capacity with growing network diameter

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Dual Radio WLAN Meshes Dual Radio Single-Channel WMNs

  Experiments –  Dual Radio Mesh –  Deutsche Telekom Labs

VoIP service performance optimization in pre-IEEE 802.11s Wireless Mesh Networks, Nico Bayer, Marcel Cavalcanti de Castro, Peter Dely, Andreas Kassler, Yevgeni Koucheryavy, Piotr Mitoraj and Dirk Staehle, in: Proceedings of the IEEE ICCSC 2008, Shanghai, China, May 26-28 2008.

VoIP

disturber

  Effect of Disturber in backhaul frequency, 3 hop

–  Significant gain in dual radio deployment in all metrics but still low performance for small packets aggregation beneficial?

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  Overview Part IV –  Dual Radio Meshes –  Multi-Channel Meshes –  Multi-Channel Single Radio –  Multi-Channel Multi Radio –  Routing Metrics for Multi-Channel –  802.11s Aspects

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Multi-Channel WLAN Meshes Multi- Channel Mesh Backhaul

Key Idea:   Multi-radio, multi-

channel Backhaul required for Carrier-Grade

  Send and receive in parallel on different channels

  Channel qualities and traffic demand vary over time, unknown a priori

  How to find the “best” channel for given link?

  How to coordinate which channel to use between what nodes at a given time?

Two Radios and Multiple Channels 6 Steps to send 4 packets

P2 P3 P4

Step = 3 Step = 4 Step = 5 Step = 6

P1

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Multi-Channel WLAN Meshes Exploit Diversity- Multiple Channels

Large number of channels available

Today’s US Spectrum Map – 300 MHz to 30 GHz

  Utilizing multiple channels in backhaul

Goal: Assign n non-interfering channels to n pair of nodes such that n packet transmissions can occur

simultaneously

Single Channel

Multiple Channels

Single Radio

Available ☺ Multiple Radio

N.A. ☺

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Multi-Channel WLAN Meshes Multi- Channel Mesh Backhaul

  With sufficient radios and sufficient channels, interference can be completely eliminated.

  For two nodes to communicate they need to share a common channel

  Channel assignment becomes crucial and influences topology

Single Channel

defer X

Internet

4 Channels 2 Radios

Internet

3

3

2

2 4

4 1

1

Routing

Channel Assignment

Influences Interference and load

Influences Topology and Capacity

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Multi-Channel WLAN Meshes Exploit Diversity- Multiple Channels

  Utilizing multiple channels in backhaul –  Manageability:

•  Different networks on different channels avoids interactions between networks –  Contention mitigation:

•  Fewer nodes on a channel reduces MAC layer contention –  Better performance via use of more spectrum

How to best utilize multiple channels in an Mesh network

with limited hardware?

W

m= Number Radios c = Number Channels w= per channel datarate

1

c

1

m

1

m m m+1

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Multi-Channel WLAN Meshes Conflict Graph

  Conflict graph –  Captures link interference between pair of links, which

•  changes dynamically and with nodes entering and leaving –  Helps in

•  capacity estimation, routing, channel assignment, power management –  Can use weight to model fractional interference and variable traffic

  Conflict Graph requires knowledge of –  packet transmission from nodes that are not “visible” –  physical location of nodes within the network –  whether or not multiple transmissions increase or decrease interference

1 2

6 4 5

3 1 - 4

1 - 2

2 - 3

4 - 5

2 - 5

3 - 6

5 - 6

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Multi-Channel WLAN Meshes Conflict Graph and Channel Assignment

  Assumptions: –  c channels Use c Colors to represent channels –  m (m < c) interfaces on each network node

  Channel Assignment Problem can be translated to Graph Coloring problem: –  Assign colors to ALL nodes in the conflict graph such that we minimize the conflicts

in parallel transmissions •  Typically max degree is minimized •  Average degree, max. independent set (subset of its vertices that are pairwise not

adjacent) are good metrics. –  Constraint: total no. of colors at a network node

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Multi-Channel WLAN Meshes Conflict Graph

Connectivity Graph:

1 2

6 4 5

3

Ch=1 Ch=6 Ch=11

1 2

6 4 5

3 1 - 4

1 - 2

2 - 3

4 - 5

2 - 5

3 - 6

5 - 6

Conflict Graph:

[Subramanian08]

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Multi-Channel Single Radio Multi-Channel, Single-Radio

  Radio Card can switch channels dynamically –  Today: 1 ms with optimisations –  Possible: 80 microsec

  Centralized Channel Assignment: Compute channel assignments using global knowledge Hard!

  Distributed: Use a modified RTS/CTS sequence to negotiate channels –  RTS: Potential channels to be used –  CTS: Receiver tells sender which channel to use

  Problem: –  How does the sender know which channel the receiver is listening on?

  Solutions mostly based on MAC layer extensions –  Receive on all channels simultaneously costly –  Use a dedicated control channel can be bottleneck –  Negotiate channel before transmission Example: MMAC –  Provide multiple rendezvous opportunities Example: SSCH

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Multi-Channel Single Radio Multi-Channel MAC - Literature

  Asis Nasipuri, Jun Zhuang, Samir R. Das, A Multichannel CSMA MAC Protocol for Multihop Wireless Networks, WCNC 1999

  [Wu 2000] Shih-Lin Wu, Chih-Yu Lin, Yu-Chee Tseng, Jang-Ping Sheu, A New Multi-Channel MAC Protocol with On-Demand Channel Assignment for Multi-Hop Mobile ad Hoc Networks, ISPAN 2000

  [Jain 2001] Nitin Jain, Samir R. Das, Asis Nasipuri, "A Multichannel MAC Protocol with Receiver-Based Channel Selection for Multihop Wireless Networks", ICCCN 2001

  [So-MobiHoc-2004] Jungmin So, Nitin Vaidya, Multi-Channel MAC for Ad Hoc Networks: Handling Multi-Channel Hidden Terminals Using A Single Transceiver, MobiHoc 2004

  [Bahl-MobiCom-2004] P. Bahl, R. Chandra, and J. Dunagan, “SSCH: Slotted Seeded Channel Hopping for Capacity Improvement in IEEE 802.11 Ad-Hoc Wireless Networks,” Proc. ACM MobiCom, 2004.

  Ritesh Maheshwari, Himanshu Gupta, Samir R. Das, Multichannel MAC Protocols for Wireless Networks, SECON 2006

  [Banerjee-SIGMETRICS-2006] Arunesh Mishra, Vivek Shrivastava, Suman Banerjee, William A. Arbaugh: Partially overlapped channels not considered harmful. 63-74. Sigmetrics 2006

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Multi-Channel, Multi-Radio Observations

  Can apply single radio solutions to multi-radio –  number of channels typically greater than the number of radios

  Single radio solutions are more power efficient –  but power is not the primary concern in most mesh networks

  Single radio solutions are less costly than multi-radio solutions –  but radios are fairly inexpensive –  However, cannot add radios at will –  How many cards give a good speedup at a reasonable cost?

  Switching speed is a problem in single radio solutions –  but switching speeds are being reduced

  When distance between nodes is large, can use partially overlapping channels

  No Need to implement MAC Co-ordination mechanisms for concurrent transmissions

–  Nodes can send and recieve in parallel using different Radios –  Several links can operate in parallel at different nodes

1 2

6 4 5

3

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Multi-Channel, Multi-Radio Issues in Multi Radio WMNs

  Multi-radio backhaul mesh use multiple channels/radios for backhaul –  Example: MeshDynamics MD4000

  Compatibility options 1.  Use standard 802.11-based hardware

(BUT: need multiple interfaces). 2.  Use 802.11, but customized hardware. 3.  Develop minor extensions to 802.11 (AKA layer 2.5) 4.  Design new MAC protocol.

  Observations –  Interface can only use a given channel at a time –  For two nodes to communicate they need to

share acommon channel –  Using multiple Radios, deafness, multi-channel hidden terminal and channel

deadlock problems can be mitigated –  Channel re-assignments might be required to improve capacity, minimize

interference from external networks, etc –  Network Partition Problems might arise

Network poorly connected

A B C

D

1,3

2,4

1,2 3,4 A B C

D

1,3

2,4

1,2 3,4

1,2

Some channels not used

A B C

D 1,2

1,2 1,2 1,2 A B C

D 1,2

1,2 1,2 A B C

D 1,2

1,2 1,2

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Multi-Channel, Multi-Radio Interference in Multi Radio WMNs

  Question: Do we still get improvement if we use 2 radios or more on Overlapping channels?

Channel X TCP

Channel Y TCP

15 cm Distance A B

C D

Same channel or channel separation of 4 causes 46% - 49% reduction in overall throughput

802.11a link causes a 22% reduction in overall throughput, and a 63% reduction in throughput on the 802.11g link.

Interference is significant, RF hardware shielding work is beneficial

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Multi-Channel, Multi-Radio Multiple Radios – Channel Assignment Issues

  How should we assign channels to each interface? –  Connectivity, Spectrum Utilization, Load Awareness, External Interference?

  Which interface should we send the packet on? –  Routing determines traffic load on the virtual links –  Need to consider channel, range, data rate diversity.

  Potential Problems –  Network Partition Problem –  Channel Dependency Ripple Effect Channel Re-assignment potentially

needs Coordination –  Topology Change Routing should be aware of Re-assignment –  Non-Convergent behaviour during Channel Re-assignment

Connectivity Optimal Capacity

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Multi-Channel, Multi-Radio Multiple Radios – Channel Assignment Issues

  Channel asignment strategies for the radios –  Classification according the timescale where channels are re-

assigned –  Static Interface Assignment

•  One channel per radio all the time –  (Semi)Dynamic Interface Assignment

•  Channels assigned dynamically (e.g. every 5 minutes) to match traffic patterns and/or to reduce internal or external interference.

•  Interference patterns can change, network may get disconnected –  Hybrid Interface Assignment

•  One channel to one radio for all time –  Channel might change on large timescale according to traffic demand

•  for all other radios, channels are assigned dynamically to match traffic patterns and/or reduce interference.

•  Most flexible.

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Multi-Channel, Multi-Radio Multiple Radios – Static Interface Assignment

  Characteristics for Static Interface Assignment –  A given interface fixed to a given channel

–  E.g. C1 assigned to Radio 1, C2 to Radio 2, etc. •  Benefit: no dynamic coordination needed, stable connectivity, better survivability

–  All nodes use common set of channels used by Mesh Connectivity Layer [Draves04] or MUP

•  Drawback: cannot use all channels, cannot consider traffic load

11

1

1

11

11

1

1

11

11

11

1

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Multi-Channel, Multi-Radio Multiple Radios – Static Interface Assignment

  Different Approaches, also using diverse set of channels –  [Marina-05] Treat Channel Assignment as Topology Control Problem,

–  use conflict graph to model interference –  Assign Channels to minimize maximum conflict weight

–  [DAS05] Use ILP to maximize # conc. transm. given connectivity constraints –  [Tang05] Statically bind interface channels by min. interference among links

Ch 2,3

 Drawback: longer routes required  Mostly Centralized Approaches

60

522

1

64

60

Not possible

52

56

52

60

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Multi-Channel, Multi-Radio Multiple Radios – Semi Dynamic Interface Assignment

  Characteristics for Semi Dynamic Interface Assignment –  Re-Assign channels at slow time scales

–  External Interference Aware, Centralized [Ramachandran06] –  Load Awareness

–  Centralized [Raniwala04] –  Distributed [Raniwala05]

Ch 2,3

Drawback: longer routes required

60

522

1

64

60

Not possible

52

56

52

60

2 radios / node, 4 channels

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Multi-Channel, Multi-Radio Interference-Aware Channel Assignment

  Interference-aware channel assignment –  External interference can severely

degrade performance •  A radio per-node monitors

data and control traffic •  Channels ranked from least

interfered to most interfered •  Ranking sent to centralized

channel assignment server (CAS) –  Internal interference between mesh links should be avoided Assign orthogonal

channels using Conflict Graph Concept •  Gather Neighbor information on delay to each neighbor and interference

estimates for all channels supported by the router’s radios –  Channel sensing and assignment can break network connectivity

•  Use dedicated radio per-router tuned to a common channel to ensure connectivity –  Uses Multi-Radio Conflict Graph (MCG) to model interference between mesh links

[Ramachandran06]

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Multi-Channel, Multi-Radio Traffic-Aware Channel Assignment

10 50 40 10 50 40

Which channel assignment is better?

  How to develop traffic-aware channel assignment algorithms?   How to estimate traffic that varies over time?   How to estimate the interference graph?   How to handle non-binary interference through RSS variation?   How much does traffic-awareness improve network performance

and when is it beneficial?

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Multi-Channel, Multi-Radio Traffic-Aware Channel Assignment

  Traffic-aware channel assignment –  Objective: For each interface, assign channels

such that resulting capacity of virtual links matches their loads

–  Link load determined by routing algorithms Joint channel assignment routing?

–  Having complete information about network topology and traffic matrix (how?), the traffic aware channel assignment problem is NP-hard

–  Centralized and Distributed Approaches

Channel Assignment

Link Capacity Estimation

Routing

Initial Link Load Estimation

Capacity ≥ Load For All Links?

Traffic Profile

Initial Link Loads

Channels

Link Capacities

Link Loads

Link Loads

Yes

No

Channels + Routes

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Multi-Channel, Multi-Radio Multiple Radios – Dynamic Interface Assignment

  Characteristics for Dynamic Interface Assignment –  Interface can switch channel when needed [So-MobiHoc-2004 , Bahl04]

•  Any channel can be used at any given time •  All Methods for Single-Radio Multiple-Channels can be used (SSCH, MMAC, ...) •  Benefit: no limitations on channel usage •  Drawback: coordination required, deafness problem

Ch 6 Ch 11

11

1

1

11

11

1

1

11

11

11

1

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Multi-Channel, Multi-Radio Multiple Radios – Hybrid Interface Assignment

  Common Control Channel [Jain01] –  One common control channel (e.g. On radio 1), many data channels

(switchable, e.g. on radio 2) –  Control channel used to negotiate, which data channel to use –  Advantages:

•  All nodes aware of busy channels •  No need for time synchronisation

–  Disadvantages •  Nodes contend for control channel Bottleneck •  When few channels available, spectrum efficiency is low •  Increased cost due to dedicated channel for control

Control Channel: 1 Control Channel: 1

Data Channel: 2-4 Data Channel: 2-4

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1

Multi-Channel, Multi-Radio Hybrid Interface Assignment - operation

  Each node has min. 2 interfaces –  min. 1 fixed, min. 1 switchable

  Benefits –  Connectivity Maintained –  Channel Diversity Achieved

  Drawback –  Large Channel Diversity leads to potentially large delay due to frequent switching

2

1 3 1

4 2

3

4

Trade-off: Channel Diversity vs. Switching Cost

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  Hybrid Interface Assignment: Fixed/Switchable Approach Net-X   Each node has at least 1 fixed, 1 switch-able interface   Connectivity is maintained, all channels used   Every node picks a channel as it’s fixed channel   Different nodes use different fixed channels   Once a “connection” is made, there may not be a reason to switch channels

again for that particular flow Per Channel Packet Queue

Packet to D

Packet to C

Ch. 4

Ch. 3

Packet to C arrives

buffer packet

Interface switches to channel 3

[Kyasanur06]

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  Hybrid Interface Assignment: Fixed/Switchable Approach Net-X   Requires Multi-channel broadcast support, Scheduling for channel switching   Hybrid Multichannel Control Protocol (HMCP)

  Challenge: Create and maintain channel diversity   Fixed Channel Selection Protocol Semi Dynamic

  On startup each node picks a random fixed channel   Periodically send a “hello” pkt. containing fixed channel & 1-hop neighbors info.

on all channels (using the switchable interface) High Overhead   Maintain a NeighborTable containing fixed channels being used by neighbors   Select the channel with fewest nodes as a candidate   Change fixed channel to candidate channel probabilistically to avoid oscillations

[Kyasanur06]

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Multi-Channel, Multi-Radio Net-X Components

Node B ath0 2

Node A ath1 1

Node C ath1 3

Node D ath1 4

Unicast Table Address Interface Channel

1 2 4

Schedule packet transmissions for ath0

2 ath0 1 ath1 3 ath1 4 ath1

Broadcast Table Channel Interface

Schedule packet transmissions for ath1

Broadcast? No Yes

Queue

Packets 3 1 2 4 3

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Multi-Channel, Multi-Radio KAUMesh – Extensions to Net-X

Multi-Channel Architecture   Based on Net-X, Linux 2.6, Cambria Platform (Gateworks)   Three 802.11a radios per mesh node (m = 2), Legacy clients with 1 radio 802.11b/g   Nagios Network Management Platform Software architecture is based on “Net-X”   QoS-aware queuing and scheduling for interface switching   QoS support for multi-radio backhaul (IEEE 802.11e based)   Real time in-network monitoring providing QoE-estimates

Channel Abstraction Layer and QoS Scheduler

IP Stack

QoS Interface Device Driver

User Applications

ARP

QoS Interface Device Driver

Multi-Channel Routing and Channel Assignment (AODV/OLSR) Cross Layer Monitoring

VoIP Observer

http://www.kau.se/en/kaumesh

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Multi-Channel, Multi-Radio Multiple Radios – Protocol Issues

Link

Network

Transport

Physical Layer

Upper layers

L2.5 1 4 3

2 3

2 4 2 4 2

Route A-B-C in use D needs route to F Route D-E-F better

  Separation on Timescale –  Routing larger time scale

•  channel aware route selection channel diverse routes •  Routing metric should include channel diversity, bandwidth, loss

rate, etc... •  Need to take into account cost of switching

–  Brown route ”better” than green Routing Metrics •  Broadcast packets need to be sent on all channels

–  Can use separate broadcast channel needs additional radio

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Routing Metrics for Multi-Channel ETT Example in Multi-Radio Environment

11 Mbps: 5% loss ETT : 0.77 ms

18 Mbps 10% loss ETT : 0.40 ms 50% loss ETT : 0.89 ms

1000 Byte Packet

6 Mbps, No Loss 6 Mbps, No Loss

6 Mbps, No Loss

1.33ms 1.33ms

1.33ms 1.33ms

6 Mbps, No Loss

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Routing Metrics for Multi-Channel Routing Metrics Revisited

Which Route is Bettter? CH=1 CH=1

CH=1 CH=2

Routing metric should account for channel diversity

and channel interference Cross-Layer Issue

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Routing Metrics for Multi-Channel Routing Metric WCETT

  Idea: WCETT [Draves04-Mobicom]: –  Used with Multi-Radio solutions MR-LQSR –  Combines individual ETTs along the path and channel diversity –  Define Xj be the sum of transmission time of hops on channel j. –  Select the path with min WCETT

Delay, does not include channel diversity short path

Channel diversity

reflects the set of hops that will have the most impact on the throughput of this path.

S

D5 41 32

6 43 2

max Xj = max(13,12,5)=13

Channel 1 Channel 2 Channel 3

Routing

Loss Ratio Datarate Frequency Diversity

Channel Access Delay

Buffer Utilization

Interference Awareness

Routing

Loss Ratio Datarate Frequency Diversity

Channel Access Delay

Buffer Utilization

Interference Awareness

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Routing Metrics for Multi-Channel Multiple Radios – Routing Issues

  In Multi-Channel –  Select routes that have channel diversity WCETT

  Need to consider Switching Cost –  Switching interfaces results in packets being queued and delayed –  If a node is on more routes, might require more switching –  Try to minimize the amount of switching while maximizing channel diversity

2 1

2 1

Which Route is better?

A-B-D or A-C-D?

3

AB

D C

E

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Routing Metrics for Multi-Channel Considering Switching Cost

  New Metric: MCETT = include switching penalty   Intuition: balance switching overhead with channel diversity   For each channel (i): measure InterfaceUsage(i), average over 1s interval   Measure probability that switchable interface is on different channel i != j when

packet arrives on channel j

  Switching Cost

  Path Metric ci = channel used on i-th hop

2 1

2 1

3

A B

D C

E

[Kyasanur06]

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802.11s Aspects IEEE 802.11s Common Channel Framework (CCF)

  Framework for a MAC protocol supporting –  single and multi channels –  single and multi radio interfaces

  Common channel: –  Unified Channel Graph on which MPs and MAPs operate (i.e. a graph formed by all

interfaces communicating on a common channel) –  The channel from which MPs switch to a destination channel and return back. –  MPs with multiple radios may use a separate common channel for each interface –  CCF supports optional channel switching in different forms

•  After RTX/CTX (Request to switch/clear to switch) exchange on common channel, MP pairs switch to a destination channel and then switch back

•  Groups of MPs may switch to a negotiated destination channel

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802.11s Aspects IEEE 802.11s –CCF: Multi-Channel Single Radio

RTX

MP1

MP2

MP3

MP4

Common Channel

Data Channel n

Data Channel m

CTX

SIFS

CTX

SIFS

RTX

DIFS

DIFS

DATA

Switching Delay

ACK

SIFS CTX

SIFS

RTX

DIFS Switching

Delay

DATA

Switching Delay DIFS

ACK

SIFS

  Using RTX, the transmitter suggests a destination channel.

  Receiver accepts/declines the suggested channel using CTX.

  After a successful RTX/CTX exchange, the transmitter and receiver switch to the destination channel.

  Switching is limited to channels with little activity.   Existing medium access schemes are reused.

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802.11s Aspects IEEE 802.11s CCF: Coordination of Channel Usage

  Channel coordination window (CCW) is defined on the common channel   At the start of CCW, CCF enabled MPs tune to the common channel.

arbitrary MPs can get connected. –  Channel Utilization Vector (U) of each MP is reset. –  MPs mark the channel as unavailable based on channel information read from RTX/CTX

frames.   P is the period with which CCW is repeated.

–  CCF enabled MPs initiate transmissions that end before P. –  MPs can stay tuned to the CC beyond CCW duration.

  P and CCW are carried in beacons.

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802.11s Aspects IEEE 802.11s CCF - Accommodating Legacy Behavior

  To devices that do not implement CCF, the common channel appears as a conventional single channel.

  Common channel can be used for data transmission.   A MAP with a single radio may use the common channel for

WDS as well as BSS traffic.   Dynamic channel selection is restricted to MPs that support CCF.

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  Absence of virtual carrier sensing –  no information of NAV and TXOP when on data channel –  collisions unavoidable

  CCF MPs must coexist with EDCA-only MPs   An ad hoc cluster of EDCA-only MPs using as primary channel either the

common channel or one of the data channels risk collisions every time a CCF MP transmits

–  CTS, ACK, or other NAV-setting frames sent by EDCA-only MPs to protect a transmission are missed by the CCF MPs while tuned to a channel other than that used by the EDCA-only MP

  CCF removed from IEEE 802.11s draft

802.11s Aspects IEEE 802.11s CCF – Critical Problems

Transmitting CCF node

Hidden node

Hidden node

Mesh points tx tx X X

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More Literature

  [Anand06] Anand Prabhu Subramanian, Milind M. Buddhikot, and Scott Miller, Interference aware routing in multi-radio wireless mesh networks, (WiMesh 2006), Reston,VA, September 2006.

  [Banerjee-SIGMETRICS-2006] Arunesh Mishra, Vivek Shrivastava, Suman Banerjee, William A. Arbaugh: Partially overlapped channels not considered harmful. , Proceedings of the joint international conference on Measurement and modeling of computer systems, Saint Malo, France 2006

  [Subramanian08] Anand Prabhu Subramanian, Himanshu Gupta and Samir Das: Minimum Interference Channel Assignment in Multi-Radio Wireless Mesh Networks, IEEE Transactions on Mobile Computing (TMC), Vol 7. Number 11. November 2008.

  [So-MobiHoc-2004] J. So and N. Vaidya. Multi-Channel MAC for Ad Hoc Networks: Handling Multi-Channel Hidden Terminals Using A Single Transceiver. In Proc. ACM MobiHoc, Tokyo, Japan, May 2004.

  [Draves04] R. Draves, J. Padhye and B. Zill, "Comparison of Routing Metrics for Multi-Hop Wireless Networks", Proceedings of ACM SIGCOMM 2004.

  [Draves04-Mobicom] Richard Draves, Jitendra Padhye, and Brian Zill. Routing in multi-radio, multi-hop wireless mesh networks. In MobiCom ’04: pp 114–128, New York, NY, USA, 2004. ACM Press.

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More Literature

  [Adya-04] Atul Adya, Paramvir Bahl, Jitendra Padhye, Alec Wolman, Lidong Zhou: A Multi-Radio Unification Protocol for IEEE 802.11 Wireless Networks. BROADNETS 2004

  [Marina-05]M. Marina, S. Das, A topology control approach for utilizing multiple channels in multi-radio wireless mesh networks, in: 2nd International Conference on Broadband Networks (Broadnets 2005), Boston, Massachusetts – USA, October 2005.

  [DAS05]A. Das, H. Alazemi, R. Vijayakumar, S. Roy, Optimization models for fixed channel assignment in wireless mesh networks with multiple radios, in: 2nd IEEE Communications Society Conference on Sensor and Ad Hoc Communications and Networks (SECON), Santa Clara, California – USA, September 2005.

  [Tang05]J. Tang, G. Xue, W. Zhang, Interference-aware topology control and QoS routing in multi-channel wireless mesh networks, in: 6th ACM International Symposium on Mobile Ad Hoc Networking and Computing (Mobihoc 2005), Urbana-Champaigne, Illinois – USA, 2005.

  [Ramachandran06] K. Ramachandran, E. Belding, K. Almeroth, M.Buddhikot, Interference-aware channel assignment in multi-radio wireless mesh networks, in: 25th Conference on Computer Communications (Infocom 2006), Barcelona – Spain, April 2006.

  [Raniwala04] A. Raniwala, K. Gopalan, T. Chiueh, Centralized channel assignment and routing algorithms for multi-channel wireless mesh networks, Mobile Computing and Communications Review 8 (2) (2004) 50–65.

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More Literature

  [Raniwala05] A. Raniwala, T. Chiueh, Architecture and algorithms for an IEEE 802.11-based multi-channel wireless mesh network, in: 24th Conference on Computer Communications (Infocom 2005), Miami, Florida – USA, March 2005.

  [Bahl04] P. Bahl, R. Chandra, J. Dunagan. SSCH: Slotted seeded channel hopping for capacity improvement in ieee 802.11 adhoc wireless networks, in: 10th ACM International Conference on Mobile Computing and Networking (MobiCom 2004), Philadelphia, Pennsylvania – USA, 2004

  [Jain01] N. Jain, S. Das, A. Nasipuri, A multichannel csma mac protocol with receiver-based channel selection for multihop wireless networks, in: 10th International Conference on Computer Communications and Networks (ICCCN 2001), Scottsdale, Arizona – USA, 2001.

  [Kyasanur06] P. Kyasanur, N. Vaidya, Routing and link-layer protocols for multi-channel multi-interface ad hoc wireless networks, SIGMOBILE Mobile Computing and Communications Review 10 (1) (2006) 31–43.

  Asis Nasipuri, Jun Zhuang, Samir R. Das, A Multichannel CSMA MAC Protocol for Multihop Wireless Networks, WCNC 1999

  Shih-Lin Wu, Chih-Yu Lin, Yu-Chee Tseng, Jang-Ping Sheu, A New Multi-Channel MAC Protocol with On-Demand Channel Assignment for Multi-Hop Mobile ad Hoc Networks, ISPAN 2000

  Ritesh Maheshwari, Himanshu Gupta, Samir R. Das, Multichannel MAC Protocols for Wireless Networks, SECON 2006

Documents

s Mesh Networks Introduction to Wirelesswireless.ictp.it/wp-content/uploads/2012/02/school... · 2012. 2. 13. · – Example: MeshDynamics MD4000 Compatibility options 1. Use standard