Using 802.11 in an FTTP Application

FTTP Application

Video Network

PSTN

Internet

Optical Line Terminal(OLT)

Telephone

Computer

Optical Network Terminal(ONT)

Television

Set Top Box

Residential Gateway

Twisted Pair

Cat5 Wiring

Coax

Feeder Fiber

Optical Splitter

ResidenceCentral Office Outside Plant

FTTP with 802.11

Video Network

PSTN

Internet

Optical Line Terminal(OLT)

Telephone

Computer

Optical Network Terminal(ONT)

Television

Set Top Box

Feeder Fiber

Optical Splitter

ResidenceCentral Office Outside Plant

802.11Network

Issues to Consider

• Equipment Availability

• Security

• Bandwidth

• Propagation distances

• Quality of Service

Service Offerings• Data Services

– 5Mbps downstream / 2Mbps upstream– 15Mbps downstream / 2 Mbps upstream– 30 Mbps downstream / 5 Mbps upstream

• Video Services– Today optical wavelength overlay– Future – IP TV

• 3-4 Mbps per channel• 19 Mbps per channel (high definition)

• Telephony Service– 4 voice channels (analog today)– VOIP – 100Kbps per voice channel

802.11 Data RatesData Rate (Mbps) 802.11b 802.11a 802.11g

1 90+ - 90+

2 75 - 75

5.5(b)/6(a/g) 60 60+ 65

9 - 50 55

11(b)/12(a/g) 50 45 50

18 - 40 50

24 - 30 45

36 - 25 35

48 - 15 25

54 - 10 20

Quality Of Service

• Voice and video data have QOS requirements

• Data services can be supported using DCF

• Consider using PCF

• Enhanced QOS mechanisms are specified in 802.11e

Point Coordination Function

PIFS

Listen before talk

BeaconSIFS

Data+CF+poll

SIFS

Data+ CF+ ACK

SIFS

CF+poll

SIFS

CF +ACK

CF-END

• ONT could be used as Point Coordinator• ONT polls phones for voice traffic• ONT can “pace” the downstream video traffic• No control over upstream data packet size• If VOIP packet size could be set, then PCF may achieve QOS• Better alternatives available from 802.11e

802.11e QOS Methods

Distributed Coordinaton Function (DCF)

PointCoordination

Function(PCF)

HCFContention

Access(EDCA)

HCFControlled

Access(HCCA)

802.11e Traffic Priorities• 8 traffic priorities are used from 802.1d

– Background (1)– Background (2)– Best Effort (0)– Best Effort (3)– Video (4)– Video (5)– Voice (6)– Voice (7)

• These are mapped to 4 Access Categories– Voice– Video– Best Effort– Background

Arbitration Inter Frame Space

HCCA

• QOS equivalent to PCF

• Allows for contention period and contention free period

• Polling in contention free period include QOS details

• Allows HC to fairly allocate medium considering QOS

• Contention period uses EDCA

Results from Simulation DCF vs EDCA

Conclusions• 802.11 could be used to deliver current FTTP

services• 802.11e can provide QOS• No growth path for HD TV• Not useful for MDU application• IP phones currently too expensive• Security can be managed with pre-shared keys• Unlikely to become a common ONT interface