xfeng ws coexistence slides icc13

8/10/2019 Xfeng Ws Coexistence Slides ICC13

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Enabling Co-channel Coexistence of

802.22 and 802.11af Systems in TV

White Spaces

Xiaojun Feng, Qian Zhang, and Bo Li

Hong Kong University of Science and Technology

IEEE ICC 2013


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Outline

Background

Coexistence Problem

Busy-tone based CoexistenceFramework

Simulation Results

Conclusions

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TV White Spaces

TV White Spaces Free TV channels after Analog to Digital

Transition

FCC rules

Sep. 2010

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Standards

IEEE 802.22

Target: Wireless Regional Area Networks

(WRAN)

MAC: TDMA-like Power: 4W (36dBm)

Sensitivity: -97 dBm.

Range: up to 100 km

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Standards

IEEE 802.11af

Target: Wireless Local Area Networks (WLAN)

MAC: CSMA

Power: 100mW (20dBm)

Sensitivity: -64 dBm.

Range: about 1km

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Source: MSR


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Heterogeneities

802.22 and 802.11af are different at

almost all levels in the protocol stack.

Comparison of some key specifications

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802.22 802.11af

MAC TDMA CSMAPower 4 W (36 dBm) 100 mW (20 dBm)

Sensitivity -97 dBm -64 dBm


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Outline

Background

Coexistence Problem


Simulation Results

Conclusions

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Coexistence Problem

Challenge 1: Hidden Terminal to 802.22

Low sensitivity of 802.11af

802.11af cannot detect 802.22 and becomes a

hidden terminal

Challenge 2: Exposed Terminal to 802.11af

High transmission power of 802.22 and TDMAMAC

802.11af can be badly blocked

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Illustrated Example

A: 802.22 Base Station (BS)

B: 802.22 CPE

C: 802.11af access point (AP)

D: 802.11af client device

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Illustrated Example

Challenge 1: Hidden Terminal to 802.22

Distance between A and B/C: = 5km

Distance between B and C/D: = 500m

Interference from C to B: = 61.6dBm

Signal from A to B: = 65.6dBm

<

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Illustrated Example

Challenge 2: Exposed Terminal to 802.11af

Distance between B and C/D is = 500m

Distance from C to D is = 20m

Interference from B to D: = 46.6dBm

Signal from C to D: = 33.2dBm

>

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Existing Solutions

802.19 protocol Centralized control

Assume devices have common interface

[7] X. Zhang and K. Shin, Enabling Coexistence ofHeterogeneous Wireless Systems: Case for Zigbeeand Wi-Fi, inACM MobiHoc2011.

[8] H. Rahul, N. Kushman, D. Katabi, C. Sodini, andF. Edalat, Learning to Share: Narrowband-Friendly Wideband Networks, in ACM MobiCom2008.

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Our New Observations

802.22 node has two antennas in both BSand CPE

TX/RX antenna:

BS: omni-directional antenna CPE: directional antenna

Sensing antenna:

Omni-directional

We can leverage the sensing antenna for

busy tone

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Outline

Background

Coexistence Problem


Simulation Results

Conclusions

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Basic Idea of Busy-tone

Let the sensing antenna at the

802.22 CPE send out busy-tone signal

with known pattern with 100 mW

power.

Self-interference cancellation at the802.22 CPE

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Busy-tone Design

Busy-tone Feasibility

70 dB self-interference cancellation can be

achieved in the literature

Busy-tone Duration

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Busy-tone Design

Exposed CPE detection

Leverage the busy-tone pattern at the

CPE.

First weak patterned busy-tone signal

Then strong non-patterned 802.22 signal

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Outline

Background

Coexistence Problem


Simulation Results

Conclusions

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Simulation Setup

The distance between the 802.22 BS andCPE: 5km~15km

We randomly generate one 802.11af AP andone 802.11af client within the carrier senserange of the busy-tone

Results are

averaged with10000 randomly

generated topologies.

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Simulation Scenarios

802.11 only

Only the 802.11af network occupying the

entire channel

802.22 only Only the 802.22 network occupying the entire

channel

Coexistence without busy-tone Coexistence with busy-tone

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Impact of the Busy-tone Scheme on

802.22 Throughput

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802.11af Throughput

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the Total Throughput

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Outline

Background

Coexistence Problem


Simulation Results

Conclusions

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Conclusions

We investigate the coexistence scenario andidentify the coexistence challenges betweenthe 802.22 and the 802.11af networks.

We proposed a busy-tone based scheme toenable the co-channel coexistence of thetwo systems.

Through extensive simulation, we show thatthe spectrum utilization can be increasedwith the proposed scheme.

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Thanks!

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Enabling Co-channel Coexistence of 802.22

and 802.11af Systems in TV White SpacesXiaojun Feng

[email protected]

xfeng ws coexistence slides icc13

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