Ricochet

- Presented byV.Sudharshan

S.Ashok

Agenda

• What is Ricochet?• Who developed it and who is promoting it?• Technical specifications• The ricochet modem• Services provided• Key features• Comparison between different architectures

Ricochet

• A mobile data access service that is always on, provides high speed, secure mobile access to the desktop from outside the office.

• It allows to link to the internet or the corporate network without needing phone lines or cable connections.

Ricochet – Timeline

• The Ricochet service was introduced by Metricom.

• It was primarily available at airports and selected locations.

• On July 2,2001, Metricom filed for bankruptcy and ricochet service was turned off.

• On Sep 2002, it was back, this time promoted by Aerie networks.

Ricochet

• The Ricochet service is a wide area wireless system using spread spectrum packet switching data.

• The network operates within 902-928 MHz portion of RF spectrum.

• The Ricochet wireless Micro Cellular Data Network (MCDN), consists of shoebox sized radio receivers, called Micro cell radios (Fig 14.4)

Ricochet• Micro cells are typically mounted to street poles.• Micro cells require a small power from the street lights.• Each Micro cell radio employs 162 frequency hopping channels.• The ricochet network has a system called name server which provides

service validation and path information.

Fig. 1 - Ricochet modem mounted on a street pole

Fig.2 – Ricochet mobile communication network

Ricochet Mobile Communication Network

Network interconnection facilityMicrocell radios onstreet lights, utility poles

Wireless access point

Name server

Router

Gateway

Gateway to Internet, Intranets, LANS, Compuserve, AOL and other on-line servicesComputer device

Modem radio

The Ricochet Wireless Modem

• It weighs 13 ounces.• Has the general dimensions of a small paperback

book, plugs directly into a desktop.• When a Ricochet modem is configured to operate

in bridge mode, it translates signals from other Ricochet modems into signals that a wired modem can receive.

The Ricochet wireless modem

Fig.3 Ricochet wireless modem

Services Provided by Ricochet

• Provides immediate, dependable and secure connections without the cost and complexities of land based phone lines.

• Sending E-mails, access to documents in home networks.

• Many real estate agents use this to search for property listings while on road.

Key Features of Ricochet Modem

• V.34, 28,800 bps access.• Good Availability• Unlimited access.• Flexible pricing.

Comparison between Different Architecture (1/2)

IEEE 802.11 Ricochet HomeRF HiperLAN Bluetooth

Operational spectrum

2.400-2.4835~5.2 GHz

902-928 MHz 2.404-2.478 GHz 5.15 GHz and 17.1 GHz 2.402-2.480 GHz

Physical layer DSSS/FHSS/IR Frequency hopping 162 hops/sec

FHSS 50 hops/sec DFS (Dynamic Frequency Selection) with BPSK/ QPSK/ QAM

FHSS 1600 hops/sec

Channel access CSMA/CA TDMA Hybrid (TDMA & CSMA/CA)

TDMA/TDD Master slave, TDMA frequency hopping

Raw data rate 2 Mbps & 11 Mbps/ 6-54 Mbps

288 1and 2 Mbps 23.5 Mbps or 54 Mbps 1 Mbps

Range 150 feet 1000 feet <150 feet 150feet 10 m to 100 m with extended range

Power consumption Not specified Not specified 100 mW Not specified 1 mW, 10 mW, 100 mW

Traffic Data (DCF) Data Voice + Data Data Voice or Data

Error robustness CRC/ARQ Type 2 CRC/ARQ type 1 1/2, 9/16, 3/4 rate FEC, ARQ type 1

1/3 rate FEC, 2/3 rate FEC and ARQ Type 1

Mobility support Not specified Yes No Yes No

Comparison between Different Architecture (2/2)

IEEE 802.11 Ricochet HomeRF HiperLAN Bluetooth

Energy conservation

Directory based Yes Yes Yes

Guaranteed latency Yes (uses PCF (Point Coordination Function))

<20 msec for voice Yes (Supports DiffServ (Differentiated Services)/ ATM/ RSVP (Resource Reservation Protocol ))

No device

Speech coding Not specified Not available 32 kbps with ADPCM

OFDM 64 kbps with CSVD/ logPCM

Security 40 bit RC4 RSARC-4 Blowfish DES, 3-DES Minimal (in PHY)

Communication topology

Peer-peer, MS-BS Peer-peer Peer-peer, MS-BS Peer-peer, MS-BS Master-slave, Master-multislave

Approx. price/point $25 Variable $18 Not specified $10

THANK YOU!!!