Distributed Spectrum Management using Inter-network Cooperation

22 Pages·2013·0.91 MB·English

Distributed Spectrum Management
using Inter-network Cooperation
Akash Baid, Ivan Seskar, Dipankar
Raychaudhuri
WINLAB, Rutgers University

WINLAB
Introduction
• Rise of large-scale, managed, unlicensed-band
wireless networks
• Overlapping deployments – time, freq, space
Location of APs
of two Wi-Fi
deployments in
Brooklyn, NY
This work explores:
1. Can networks cooperate on an aggregated manner?
2. How can such cooperation be practically realized?
WINLAB
Inter-network Cooperation
• Interaction between managed wireless networks
over the back-end wired link for making more
efficient use of the spectrum
Policy/capabilities Policy/capabilities
Controller type: C2 Controller type: C2
Algorithm
Information sharing enabled Information sharing enabled
& policy negotiation
Merge RRM enabled Merge RRM enabled

Aggregate radio map Aggregate radio map
Network A Network B
Range of operation: (x , y r ) Range of operation: (x , y r )
B B, B B B, B
Technology type: Wi-Fi Spectrum info Technology type: Wi-Fi
Device list: A1 params, A2 exchange Device list: B1 params, B2
params, … params, …

Per device parameters Per device parameters
Radio device A1 Radio device B1
Type: Transmit/Receive (client) Type: Transmit/Receive (client)
Location: (x , y ) Location: (x , y )
A1 A1 B1 B1
Power, BW, frequency, duty cycle Power, BW, frequency, duty cycle
WINLAB
Outline
• Potential gains from cooperation
– Client-association optimization problem
– Non-linear integer program and its solution
– Simulation results

• Realizing inter-network cooperation
– A SDN framework for the wireless control plane
– ControlSwitch: Flexible switching of control msgs
– Example use-cases
WINLAB
Client-AP association optimization
Default Selection:
5247 MMbbppss
Connect to closest (AP1)
4284 MMbbppss
Intra-network optimization:
Take AP load into account
(AP2)
36 Mbps
Inter-network optimization:
Take effect of foreign APs
into account (AP3)
Intra-network optimization of client-AP associations can
lead to inefficient results in presence of foreign networks
WINLAB
Study of potential gains
• Comparison of least distance, intra-network, and
inter-network optimization

• System Model:
– 𝑁 independent WiFi networks: indexed by 𝑖
– 𝐴 Access Points; 𝑈 Clients in the 𝑖th network
𝑖 𝑖

𝑥 (k) connection state between the 𝑗th client and 𝑘th AP of
𝑖𝑗
the 𝑖th network
𝑝 (k) fraction of time provided by the AP to the client
𝑖𝑗
𝑟 (k) effective bit rate
𝑖𝑗
𝐵 set of co-channel foreign APs within carrier sense range
𝑖𝑘
𝐶 set of co-channel foreign APs outside carrier sense but
𝑖𝑘
within interference range (potential hidden nodes)
WINLAB
Optimization Problem
Intra-network Optimization:
Cooperative inter-network Optimization: This information is
through info-sharing
between networks
WINLAB
Simulation Details
• Both are non-linear integer programs:
– 2 + ∈ approximate solution in polynomial time
– For cooperative, problem decomposes into parts which
each network can solve on its own

• Settings:
– 2-6 overlapping networks, 15-35 APs/network, 50-250
clients/network
– Two types of deployments: Uniform-random, Clustered

• Assumptions:
– Downlink only, full-buffer traffic
– Proportional fair scheduling at each AP
– No priority between clients
WINLAB
Random Deployment Results
‒ 500 x 500m area
‒ Min. separation of 50m
between APs of same network
‒ No minimum across networks
2x gains in low rate clients,
slight gain in median
WINLAB
Clustered Deployment Results
• APs of Network 1 clustered in three 200x200m square regions
Network 1
1
Net 1 APs are clustered
Least Distance
0.8 Intra-Network ⇓
Cooperative
0.6 Effect of Net 2 APs is less
F
D ⇓
C
0.4
Info from Net 2 not very
0.2
useful
0
-2 -1 0 1 2
10 10 10 10 10
Client Rates (Mbps)
Network 2
1
Net 1 APs are clustered
Least Distance
0.8 Intra-Network ⇓
Cooperative
0.6 Effect of the cluster of
F
D
C Net 1 APs on Net 2 is high
0.4
7x Gain in
10 %ile ⇓
0.2 throughput
Info from Net 1 helps a lot
0
-2 -1 0 1 2
10 10 10 10 10
WINLAB
Client Rates (Mbps)