a perspective on network interference and multiple access control michael j. neely university of...
TRANSCRIPT
A Perspective on Network Interference and Multiple Access Control
Michael J. NeelyUniversity of Southern California
May 2008
Capacity Region
1 Wireless Link = AWGN Channel 1 Wireless Link = ON/OFF Channel
“information theory” “queueing theory”
+Symbols
Noise
C = log(1 + SNR)
Packet Arrivals Pr[ON]=p
C = p packets/slotCapacity: Capacity:
Mathematical Models for a Wireless System (two meaningful perspectives)
-Symbol-by-symbol transmission
-Capacity optimizes bit rate over all coding of symbols (Shannon Theory)
-Slot-by-slot packet transmission
-Capacity is obvious (Basic Queueing Theory)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-User Gauss. Broadcast Downlink N-User Downlink (Fading Channels)
“information theory” “queueing theory”
bitsbits
bits
ON/OFF
ON/OFF
ON/OFF
-Symbol-by-symbol transmission
-Capacity is a REGION of achievable bit rates
-Optimizes coding of symbols
-Opportunistic scheduling
-Observe ON/OFF channels, decide which queue to serve (“collision free” = easy)
-Capacity is a REGION of achievable rates
Mathematical Models for a Wireless System (two meaningful perspectives)
N-User Gauss. Broadcast Downlink N-User Downlink (Fading Channels)
“information theory” “queueing theory”
bitsbits
bits
ON/OFF
ON/OFF
ON/OFF
Capacity Region:all (1,…, N) s.t. Capacity Region: all (1,…, N) s.t.
for all subsets K of users.
[Tassiulas & Ephremides 93](degraded Gauss. BC)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node Static Multi-Hop Network(multiple sources and destinations)
“information theory” “queueing theory”
N-Node Static Multi-Hop Network(multiple sources and destinations)
-Symbol-by-Symbol Transmissions-Optimize the coding
Capacity = ???
-Optimize Scheduling/Routing-General Interference Sets
Capacity = Known Exactly (Multi-Commodity Flow Subject to “Graph Family” Link Constraints)
[Backpressure, Tassiulas, Ephremides 92]
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Mathematical Models for a Wireless System (two meaningful perspectives)
N-Node MANET
“info theory” “queueing theory”
Capacity = ???
N-Node MANET
Capacity = Known Exactly
[Neely, Modiano, et. al. JSAC 05, IT 05]
-Ergodic Mobility-Optimize the Scheduling/Routing-General Channel Interference Models (SINR, Collision Sets, etc.)
Capacity Region
The Theory: Generalized Max-Weight Matches, Backpressure
Georgiadis, Neely, Tassiulas, Foundations and Trends in Networking, 2006.http://www-rcf.usc.edu/~mjneely/pdf_papers/NOW_stochastic_nets.pdf
General Interference Models
Multi-hop
Max: [Wl(t)C(I(t), S(t)) - VCostl(t)]
Control Action Topology State
Capacity Region
The Theory: Generalized Max-Weight Matches, Backpressure
Georgiadis, Neely, Tassiulas, Foundations and Trends in Networking, 2006.http://www-rcf.usc.edu/~mjneely/pdf_papers/NOW_stochastic_nets.pdf
General Interference Models
Multi-hop
Max: [Wl(t)C(I(t), S(t)) - VCostl(t)]
Control Action Topology State
Capacity Region
The Theory: Generalized Max-Weight Matches, Backpressure
Georgiadis, Neely, Tassiulas, Foundations and Trends in Networking, 2006.http://www-rcf.usc.edu/~mjneely/pdf_papers/NOW_stochastic_nets.pdf
Multi-hop
General Interference Models
Max: [Wl(t)C(I(t), S(t)) - VCostl(t)]
Control Action Topology State
Capacity Region
The Theory: Generalized Max-Weight Matches, Backpressure
*Max: Wl(t)C(I(t), S(t))
Control Action Topology State
*[Neely Thesis 03] *[Georgiadis, Neely, Tassiulas, NOW F&T 2006] http://www-rcf.usc.edu/~mjneely/pdf_papers/NOW_stochastic_nets.pdf
*Maximizing to within a factor yields -factor throughput region!
Multi-hop
General Interference Models
The Issues: (A comparison to info theory)
“info theory” “queueing theory”
-Capacity log(1+SNR) known exactly
-Randomized Coding can achieve capacity but… …Complexity and Delay!
-Shannon Created the Challenge:
Prompted years of research in thedesign of efficient, low complexityCodes that perform near capacity(analytically or experimentally) was the research.
Turbo-codes work well experimentally!
-Capacity Region characterized exactly (in terms of optimization)
-Randomized Scheduling can achieve full Capacity… [Tassiulas 98] [Modiano, Shah, Zussman 2006] [Erylimaz, Ozdaglar, Modiano 07] [Shakkottai 08] [Shah 08] [Jiang, Walrand 08], etc.
-But Complexity and Delay is the Challenge! [Neely et al. 02], [Shah, Kopikare 02], etc.
Final Slide: Two Suggested Approaches: 1) The Analogy:
Information Theory ==> Design of Codes to work well in practice, Turbo Codes
Network Queue Theory ==> Design of practical MAC Scheduling Protocols, Implementation, “Turbo” Multiple Access
Eg: *[Bayati, Shah, Sharma 05] (uses iterative detection theory) [Modiano, Shah, Zussman 2006], [Erylimaz, Ozdaglar, Modiano 07] [Shakkottai 08], [Shah 08], [Jiang, Walrand 08],etc.
2) “Beyond Links”: Combine PHY layer and Networking
MIMO [Kobayashi, Caire 05]Cooperative Comms [Yeh, Berry 05]Network Coding [Ho, Viswanathan 05], [Lun, Medard 05]Multi-Receiver Diversity [Neely 06] broadcasting
error