Exploiting Diversity in the Network

1
Exploiting Diversity in the Network

• Jerry Le
• Nov 29 2006

2
Preface

• Higher-quality data transfer
• - requiring more efficiently use of network
  resource
• Types of resource paths, channels,
• Types of diversity
• - by resources multi-path, multi-channel
• - by who use it diversity of single user,
  diversity of network

3
Preface

• Content covered

Not comprehensive, but hopefully insightful

• Essential problems
• - how to find diversity
• - how much diversity needed
• - how to allocate data
• - benefit vs. overhead
• - other related research issues

4
Outline

• Preface
• Multi-path in Wireless Networks
• - Representative routing protocols
• - Major issues
• - Application (video streaming)
• Multi-path in Wired Networks
• Multi-channel in Wireless Networks
• Summary Discussion

5
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• An example first

Loop-free by sequence number and
hop-count Path selection 1) link-disjoint
2) node-disjoint 3) non-disjoint
6
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• Main components
• - Paths discovery (link-disjoint, node-disjoint)
• - How to use multi-path (backup, split traffic)
• Protocols
• - AOMDV 1 (Ad hoc On-demand Multi-path
  Distance Vector Routing)
• link-disjoint, loop-free, use alternative paths
  as backup
• improve delay (100), routing load (20), same
  delivery ratio
• - SMR 2 (Split Multi-path Routing)
• 2 paths shortest path, and the maximally
  disjoint path
• Per-packet allocation among the paths
• improve delay (100), packet loss (800),
  delivery ratio (25)

Note higher mobility, larger improvement
1 Marina, M. K., and Das, S. R. On-demand
multipath distnace vector routing in ad hoc
networks. In Proceedings of the Ninth
International Conference on Network Protocols
(ICNP) (2001) 2 Lee, S. J., and Gerla, M.
Split multipath routing with maximally disjoint
paths in ad hoc networks. In Communications,
2001. ICC 2001. IEEE International Conference on
(2001), vol. 10, pp. 3201-3205 vol.10.
7
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• Load Balancing
• 3 higher allocation granularity (per-packet),
  more adaptability, more equitable distribution
• 4 Upper-bound of average route length to
  guarantee better load balancing than shortest
  path routing
• 5 Counter opinion no load balancing, unless
  using a huge number of paths (gt100), in high
  density network

Really depends on your model (density,
path-selection, etc.)
3 Krishnan, R., and Silvester, J. Choice of
allocation granularity in multipath source
routing schemes. In Proceedings of IEEE
INFOCOM'93 (1993). 4 Peter P. Pham and Sylvie
Perreau, Performance Analysis of Reactive
Shortest Path and Multi-path Routing Mechanism
With Load Balance, In Proceedings of INFOCOM03
(2003). 5 Ganjali, Y., and Keshavarzian, A.
Load balancing in ad hoc networks Single-path
routing vs. multi-path routing. In Proceedings
of INFOCOM04 (2004).
8
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• Load Balancing
• network model of 5
• - high density network with
• a huge number of paths,
• - K first shortest path routing
• result
• - paths are confined within
• a small rectangle region
• - load distribution almost the
• same with single path
• unless Kgt100

5 Ganjali, Y., and Keshavarzian, A. Load
balancing in ad hoc networks Single-path routing
vs. multi-path routing. In Proceedings of
INFOCOM04 (2004).
9
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• How many paths needed?
• AODMV 1 a few
• SMR 2 2
• 4 no more than three (due to significant
  overhead)
• 6 more paths, higher probability of
  successful transmission
• 5 greater than 100

4 Peter P. Pham and Sylvie Perreau,
Performance Analysis of Reactive Shortest Path
and Multi-path Routing Mechanism With Load
Balance, In Proceedings of INFOCOM03
(2003). 5 Ganjali, Y., and Keshavarzian, A.
Load balancing in ad hoc networks Single-path
routing vs. multi-path routing. In Proceedings
of INFOCOM04 (2004). 6 R. Rom, I. Cidon and Y.
Shavitt. Analysis of Multi-path Routing. In
IEEE/ACM Transactions on Networking, 1999
10
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• Multi-path overhead
• - More Routing Request (RREQ) and Routing Reply
  (RREP) VS. Lower flooding frequency
• - 4 the overhead grows significantly when
  path number exceeds 3
• - 2 route-rediscovery when
• a) one route fails b) all routes fail

2 Lee, S. J., and Gerla, M. Split multipath
routing with maximally disjoint paths in ad hoc
networks. In Communications, 2001. ICC 2001.
IEEE International Conference on (2001), vol. 10,
pp. 3201-3205 vol.10. 4 Peter P. Pham and
Sylvie Perreau, Performance Analysis of Reactive
Shortest Path and Multi-path Routing Mechanism
With Load Balance, In Proceedings of INFOCOM03
(2003).
11
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• Interference among paths
• 7 coupling between paths reduce almost half
  of the gains
• 8 correlation (between node-disjoint paths)
• Other issues
• Traffic allocation methods
• Packet reordering
• TCP-friendly multi-path protocol
• Source coding ( (N,k) coding, video coding)

7 Pearlman, M.R., Haas, Z.J., Sholander, P. and
Tabrizi, S.S. On the impact of alternate path
routing for load balancing in mobile ad hoc
networks. in Proceedings of ACM MobiHoc00
(2000). 8 Wu, K. and Harms, J. Performance
Study of a Multipath Routing Method for Wireless
Mobile Ad Hoc networks. In Proceedings of
Symposium on Modeling, Analysis and Simulation on
Computer and Telecommunication Systems (2001)
99-107
12
Multi-path in Wireless Networks1. Representative
routing protocols 2. Major issues 3. Application

• Wireless Video Streaming by Multi-path
• - Multi-description coding (MDC)
• Transmit equal sub-streams among multiple
  paths
• - Layered coding (LC)
• Transmit Base layer along primary path
• Transmit Enhancement layers among other paths
• - Comparison 9
• Acceptable retransmission of the base layer,
  feasible for unequal paths LC preferred
• Stringent delay constraint, path relatively
  equal MDC preferred
• - Recent work 10 (a Generic Algorithm approach)

9 Wang, Y., Panwar, S., Lin, S. and Mao, S.
Wireless Video Transport Using Path Diversity
Multiple Description Coding vs. Layered Coding.
In Proceedings of the IEEE International
Conference on Image Processing (2002). 10 S.
Mao, Y.T. Hou, X. Cheng, H.D. Sherali and S.F.
Midkiff. Mltipath routing for multiple
description video in wireless ad hoc networks,
In Proceedings of IEEE INFOCOM05 (2005)
13
Outline

• Preface
• Multi-path in Wireless Networks
• Multi-path in Wired Networks
• - Overview
• - Representative protocols
• - Major issues
• - Application (media streaming)
• - Inter-domain Multi-path Routing
• Multi-channel in Wireless Networks
• Summary Discussion

14
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• Whats similar
• - Path discovery and maintenance
• - Traffic allocation among the paths
• Whats different
• - More capability for centralized control (e.g.
  Link-state routing protocols)
• - More considerations on Traffic Engineering and
  Congestion Control
• - Interdomain multipath routing

15
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• 11 OSPF2 (Equal Cost Multi-path Protocol)
• - Per-packet Round-robin forwarding among
  equal-cost paths
• 12 Optimized ECMP
• - Traffic allocation based on load information
  (obtained by Opaque LSA)
• 13 MPDA
• - Link-state protocol approximating minimum
  delay, providing load balancing
• 14 MDVA
• - Distance-vector protocol, preventing
  Count-to-Infinity problem by ensuring
  instantaneous loop-freeness.

11 Moy, J. Ospf version 2. IETF RFC 2328
(1998). 12 Villamizar, C. Ospf optimized
multipath (ospf-omp). Expired Internet
Draft, IETF, available at http//www3.ietf.org/pro
ceedings/98dec/I-D/draft-ietf-ospf-omp-01.txt,
October 1998. 13 Vutukury, S., and
Garcia-Luna-Aceves, J. A simple approximation to
minimum delay routing. In Proceedings of ACM
SIGCOMM'99 (1999). 14 Vutukury, S., and
Garcia-Luna-Aceves, J. Mdva. A distance-vector
multipath routing protocol. In Proceedings of
INFOCOM'01 (2001).
16
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• Optimal routing/traffic allocation
• - 15
• 1) LP problem to minimize total link cost
  (given traffic demand)
• 2) Solving the problem, get optimal routing
  and allocation
• 3) Try to get optimal link weight, so that
  ECMP can achieve optimal routing (NP-hard)
• 4) A heuristic approach performs near
  optimal

15 Fortz, B., and Thorup, M. Internet traffic
engineering by optimizing ospf weights. In
Proceedings of INFOCOM 2000 (2000). 16 Wang,
Z., Wang, Y., and Zhang, L. Internet traffic
engineering without full mesh overlaying. In
Proceedings of INFOCOM 2001 (2001).
17
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• Optimal routing/traffic allocation
• - 16
• 1) LP problem to minimize the maximum of link
  utilization (other objectives are possible)
• 2) Link weight can be derived through dual
  solution of the optimal routing problem
• 3) Optimal routing is always shortest paths
  routing, if setting weights properly!

15 Fortz, B., and Thorup, M. Internet traffic
engineering by optimizing ospf weights. In
Proceedings of INFOCOM 2000 (2000). 16 Wang,
Z., Wang, Y., and Zhang, L. Internet traffic
engineering without full mesh overlaying. In
Proceedings of INFOCOM 2001 (2001).
18
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• Multi-path Transmission with Hop-by-Hop TCP
• 17 Study path-selection and rate control on
  each path to maximize the aggregate sending rate
• - path-selection for any rate controller is
  NP-hard
• - two rate controller UCmaxmin UCmaxflow
• - simple path-selection (round-robin), UCmaxmin
  and small path numbers (2-4) performs reasonably
  well
• - fairness between multi-path and single-path
  flows

17 Wang, B., Kurose, J., Towsley, D., and Wei,
W. Multipath overlay data transfer. Umass
CMPSCI Technical Report, 05-45 (2005).
19
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• Multi-path TCP
• 18 Multi-path congestion controller
• - work with a feedback of round-trip delay
• - modify Kellys utility function to get unique
  solution
• - stable when the arrival rate on each link does
  not exceed capacity

18 Han, H., Shakkottai, S., Hollot, C.,
Srikant, R., and Towsley, D. Multi-path tcp A
joint congestion control and routing scheme to
exploit path diversity in the internet. IEEE/ACM
Transactions on Networking (2006).
20
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• Traffic allocation 18, 19
• 19 three main approaches
• - modulo-N hash
• - hash-threshold
• - highest random weight
• 20 analysis of hash-threshold
• (performance, complexity, disruption)

19 Thaler, D., and Hopps, C. Multipath issues
in unicast and multicast next-hop selection.
IETF RFC 2991 (2000). 20 Hopps, C. Analysis of
an equal-cost multi-path algorithm. IETF RFC
2992 (2000).
21
Multi-path in Wired Networks1. Overview 2.
Representative protocols 3. Major issues

• Packet reordering
• - General Measurement Analysis 21,22
• (reorder packets distributions, mean of
  delay, etc.)
• - Analysis of reordering due to multi-path
  routing 23
• 1) A model to quantify Reorder Density (RD)
  with respect to delay variation among paths and
  forwarding probabilities.
• 2) Two-path case RD distributions are mirror
  images for complementary probabilities of packets
  taking alternate path

21 S. Jaiswal, G. Iannaccone, C. Diot, J.
Kurose and D. Towsley. Measurement and
Classification of Out-of-sequence Packets in
Tier-1 IP Backbone. In Proceedings of INFOCOM03
(2003). 22 Y. Xia and D. Tse. Analysis on
Packet Resequencing for Reliable Network
Protocols. In Proceedings of INFOCOM03
(2003) 23 Nischal M. Piratla and Anura P.
Jayasumana. Reordering of Packets due to
Multipath Forwarding An Analysis. In
Proceedings of IEEE International Conference on
Communications (ICC 2006).
22
Multi-path in Wired Networks4. Application 5.
Inter-domain multi-path routing

• Media streaming using path diversity
• - 24 an overview
• - Coding issues Multi-Description vs.
  Single-Description vs. Layered-Description
• MD LD less efficiency in coding, but
  suitable for streaming
• - Approaches
• 1) Single-sender Path Diversity
• 2) Multiple-sender Path Diversity

24 Apostolopoulos, J., and Trott, M. Path
diversity for enhanced media streaming. IEEE
Communication Magazine Special Issue Proxy
Support Streaming Internet, 8 (2004), 80-87.
23
Multi-path in Wired Networks4. Application 5.
Inter-domain multi-path routing

• MIRO 25
• More flexibility
• - AS-level path-selection
• - Negotiation for alternate paths
• Easy to deploy
• - Todays BGP already has alternate paths
• Benefits
• - Security
• - Load balancing

25 Xu, W., and Rexford, J. Miro Multi-path
interdomain routing. In Proceedings
of SIGCOMM'06 (2006).
24
Outline

• Preface
• Multi-path in Wireless Networks
• Multi-path in Wired Networks
• Multi-channel in Wireless Networks
• - Overview
• - Single sending node on multi-channel
• - Multiple nodes on multi-channel
• Summary Discussion

25
Multi-channel in Wireless Networks1. Overview
2. Single sending node on multi-channel

• Whats not covered
• - Spatial reuse26
• - Space-time coding 26
• Focus on
• - Single node having multiple NICs
• - Network having multiple available channels

26 S.N. Diggavi, N. Al-Dhahir, A. Stamoulis and
A.R. Calderbank. Great expectations the value
of spatial diversity in wireless networks. In
Proceedings of IEEE. Vol.92, No.2, February 2004
26
Multi-channel in Wireless Networks1. Overview
2. Single sending node on multi-channel

• Benefit of sending on multi-channel 27
• - Equivalent channels more applicable (and good
  enough)
• - (N,k) source coding Metric Effective sending
  Rate (ER)
• - 3 channels provide 60 of the ER gains
• Experimental study 28
• - Senders with two NICs
• - Open-loop, packet-level diversity
• - Practical issues (channel tuning, transmission
  patterns, etc.)
• - Senders with single NIC but switching among
  channels still have meaningful improvement

27 Vergetis, E., Guerin, R., and Sarkar, S.
Realizing the benefits of user-level channel
diversity. ACM Computer Communication Review 35,
5 (2005). 28 Vergetis, E., Pierce, E., Blanco,
M., and Guerin, R. Packet-lever diversity - from
theory to practice An 802.11-based experimental
investigation. In Proceedings of ACM Mobicom'06
(2006).
27
Multi-channel in Wireless Networks2. Single node
on multi-channel 2. Multiple nodes on
multi-channel

• Routing in Multi-radio ad hoc network 29
• - Each node has multiple NICs
• - An upgraded version of ETX-metric routing 30
• - A good path has
• 1) high successful transmission probability
• 2) high channel diversity among the path

29 Draves, R., Padhye, J., and Zill, B.
Routing in multi-radio, multi-hop wireless mesh
networks. In Proceedings of ACM Mobicom'04
(2004). 30 D. De Couto, D. Aguayo, J. Bicket,
and R. Morris. High-throughput path metric for
multi-hop wireless routing. In Proceedings of
ACM MOBICOM03, 2003.
28
Multi-channel in Wireless Networks2. Single node
on multi-channel 2. Multiple nodes on
multi-channel

• Routing and Channel Assignment in Multi-hop
  infrastructure-based wireless network 31
• - Each node has single NIC
• - Majority download traffic
• - Load balancing among APs
• (hence among channels)
• - Nodes on same channel
• along one path
• - Routing Channel Assignment

31 So, J., and Vaidya, N. H. Routing and
channel assignment in multichannel
multihop wireless networks with single network
interface. In The Second International
Conference on Quality of Service in Heterogeneous
Wired/Wireless Networks (QShine) (2005).
29
Multi-channel in Wireless Networks2. Single node
on multi-channel 2. Multiple nodes on
multi-channel

• Capacity of multi-channel multi-hop network 32
• - C available channels, m interfaces (NICs) per
  node (mC)
• - for Arbitrary Network33, when mltC, capacity
  decrease
• - for Random Network33, when CO(log(n)),
  capacity remains as in 33 ( )
• - for Random Network33, switching delay will
  not affect capacity if multiple NICs used
• Active group on multi-channel wireless network
• http//www.crhc.uiuc.edu/wireless/

32 Kyasanur, P., and Vaidya, N. H. Capacity of
multi-channel wireless networks Impact of number
of channels and interfaces. In ACM Mobicom'05
(2005). 33 Piyush Gupta and P. R. Kumar, The
Capacity of Wireless Networks, IEEE Transactions
on Information Theory, vol. 46, no. 2,
pp.388404, March 2000.
30
Outline

• Preface
• Multi-path in Wireless Networks
• Multi-path in Wired Networks
• Multi-channel in Wireless Networks
• Summary Discussion

31
Summary Discussion

• By the numbers
• - 23 paths is enough for most cases 1,2,4,17
• - dont let number of paths exceed 3 4
• - upper bound for route length 4
• - delay improve by a factor of 2 by multi-path
  in wireless networks 1,2
• - 3 channels can realize 60 of the benefits
  27,28
• - ER-rate gains using 3 channels 20 27
• - equal channels are good enough 27
• - high channel diversity along the path 29
• - no channel diversity along the path 31

32
Summary Discussion

• Problems not so hot
• - How to find/maintain paths
• Problems still open
• - Analysis of various traffic allocation method
  and their impact on performance
• - Path-selection to maximize aggregate sending
  rate
• - Channel diversity on single node27 combined
  with channel assignment for the whole network31
  (How to use multi-channel efficiently)
• - Multi-path in Multi-channel networks
• -

33
Summary Discussion

• Other forms of diversity
• - P2P
• - Gossip 34
• - Network coding

Keeping a diversity-mind
34 E Modiano et al, Maximizing Throughput in
Wireless Networks via Gossiping, In ACM
Sigmetrics 2006
34
Reference

• Multi-path routing in wireless networks
• 1 Marina, M. K., and Das, S. R. On-demand
  multipath distnace vector routing in ad hoc
  networks. In
• Proceedings of the Ninth International Conference
  on Network Protocols (ICNP) (2001)
• 2 Lee, S. J., and Gerla, M. Split multipath
  routing with maximally disjoint paths in ad hoc
  networks. In
• Communications, 2001. ICC 2001. IEEE
  International Conference on (2001), vol. 10, pp.
  3201-3205 vol.10.
• 4 Peter P. Pham and Sylvie Perreau,
  Performance Analysis of Reactive Shortest Path
  and Multi-path Routing
• Mechanism With Load Balance, In Proceedings of
  INFOCOM03 (2003).
• 5 Ganjali, Y., and Keshavarzian, A. Load
  balancing in ad hoc networks Single-path routing
  vs. multi-path
• routing. In Proceedings of INFOCOM04 (2004).
• 6 R. Rom, I. Cidon and Y. Shavitt. Analysis of
  Multi-path Routing. In IEEE/ACM Transactions on
  Networking,
• 1999
• 7 Pearlman, M.R., Haas, Z.J., Sholander, P. and
  Tabrizi, S.S. On the impact of alternate path
  routing
• for load balancing in mobile ad hoc networks. in
  Proceedings of ACM MobiHoc00 (2000).
• 8 Wu, K. and Harms, J. Performance Study of a
  Multipath Routing Method for Wireless Mobile Ad
  Hoc networks. In Proceedings of Symposium on
  Modelling, Analysis and Simulation on Computer
  and Telecommunication Systems (2001) 99-107
• 9 Wang, Y., Panwar, S., Lin, S. and Mao, S.
  Wireless Video Transport Using Path Diversity
  Multiple Description Coding vs. Layered Coding.
  In Proceedings of the IEEE International
  Conference on Image Processing (2002).
• 10 S. Mao, Y.T. Hou, X. Cheng, H.D. Sherali and
  S.F. Midkiff. Mltipath routing for multiple
  description video in
• wireless ad hoc networks, In Proceedings of IEEE
  INFOCOM05 (2005)

35
Reference

• Multi-path routing in wired networks
• 3 Krishnan, R., and Silvester, J. Choice of
  allocation granularity in multipath source
  routing schemes.
• In Proceedings of IEEE INFOCOM'93 (1993).
• 11 Moy, J. Ospf version 2. IETF RFC 2328
  (1998).
• 12 Villamizar, C. Ospf optimized multipath
  (ospf-omp). Expired Internet Draft,
• IETF, available at http//www3.ietf.org/proceeding
  s/98dec/I-D/draft-ietf-ospf-omp-01.txt, October
  1998.
• 13 Vutukury, S., and Garcia-Luna-Aceves, J. A
  simple approximation to minimum delay routing.
  In Proceedings of ACM SIGCOMM'99 (1999).
• 14 Vutukury, S., and Garcia-Luna-Aceves, J.
  Mdva. A distance-vector multipath routing
  protocol. In Proceedings of INFOCOM'01 (2001).
• 15 Fortz, B., and Thorup, M. Internet traffic
  engineering by optimizing ospf weights. In
  Proceedings of INFOCOM 2000 (2000).
• 16 Wang, Z., Wang, Y., and Zhang, L. Internet
  traffic engineering without full mesh
  overlaying. In Proceedings of INFOCOM 2001
  (2001).
• 17 Wang, B., Kurose, J., Towsley, D., and Wei,
  W. Multipath overlay data transfer. Umass
  CMPSCI Technical Report, 05-45 (2005).
• 18 Han, H., Shakkottai, S., Hollot, C.,
  Srikant, R., and Towsley, D. Multi-path tcp A
  joint congestion control
• and routing scheme to exploit path diversity in
  the internet. IEEE/ACM Transactions on
  Networking (2006).
• 19 Thaler, D., and Hopps, C. Multipath issues
  in unicast and multicast next-hop selection.
  IETF RFC 2991 (2000).
• 20 Hopps, C. Analysis of an equal-cost
  multi-path algorithm. IETF RFC 2992 (2000).
• 24 Apostolopoulos, J., and Trott, M. Path
  diversity for enhanced media streaming. IEEE
  Communication Magazine Special Issue Proxy
  Support Streaming Internet, 8 (2004), 80-87.

36
Reference

• Packet-reordering
• 21 S. Jaiswal, G. Iannaccone, C. Diot, J.
  Kurose and D. Towsley. Measurement and
  Classification of Out-of-sequence Packets in
  Tier-1 IP Backbone. In Proceedings of INFOCOM03
  (2003).
• 22 Y. Xia and D. Tse. Analysis on Packet
  Resequencing for Reliable Network Protocols. In
  Proceedings of INFOCOM03 (2003)
• 23 Nischal M. Piratla and Anura P. Jayasumana.
  Reordering of Packets due to Multipath
  Forwarding An Analysis. In Proceedings of IEEE
  International Conference on Communications (ICC
  2006).
• Multi-path Inter-domain Routing
• 25 Xu, W., and Rexford, J. Miro Multi-path
  interdomain routing. In Proceedings of
• SIGCOMM'06 (2006).
• Multi-channel in wireless networks
• 26 S.N. Diggavi, N. Al-Dhahir, A. Stamoulis and
  A.R. Calderbank. Great expectations the value
  of spatial diversity in wireless networks. In
  Proceedings of IEEE. Vol.92, No.2, February 2004
• 27 Vergetis, E., Guerin, R., and Sarkar, S.
  Realizing the benefits of user-level channel
  diversity. ACM Computer Communication Review 35,
  5 (2005).
• 28 Vergetis, E., Pierce, E., Blanco, M., and
  Guerin, R. Packet-lever diversity - from theory
  to practice An 802.11-based experimental
  investigation. In Proceedings of ACM Mobicom'06
  (2006).
• 29 Draves, R., Padhye, J., and Zill, B.
  Routing in multi-radio, multi-hop wireless mesh
  networks. In Proceedings of ACM Mobicom'04
  (2004).
• 30 D. De Couto, D. Aguayo, J. Bicket, and R.
  Morris. High-throughput path metric for
  multi-hop wireless routing. In Proceedings of
  ACM MOBICOM03, 2003.
• 31 So, J., and Vaidya, N. H. Routing and
  channel assignment in multichannel multihop
• wireless networks with single network interface.
  In The Second International Conference
• on Quality of Service in Heterogeneous
  Wired/Wireless Networks (QShine) (2005).
• 32 Kyasanur, P., and Vaidya, N. H. Capacity of
  multi-channel wireless networks
• Impact of number of channels and interfaces. In
  ACM Mobicom'05 (2005).
• 33 Piyush Gupta and P. R. Kumar, The Capacity
  of Wireless Networks, IEEE Transactions on
  Information Theory, vol. 46, no. 2, pp.388404,
  March 2000.

37
Thanks for your attention!