Broadband and Personal Area Network Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University

Outline Overview. Broadband. Personal Area Network Wi-Fi. Bluetooth.

Overview

Broadband Speed 56k modem: 96sec - 1.5min ISDN-data : 43 seconds DSL: sec Cable 2-way ( faster than or = to DSL )

DSL Modem over PSTN Carry data over voice networks. Slow and difficult to handle. Digital Subscriber Line (DSL) Dedicate line using special modems to transmit digital information. Use the existing PSTN. ADSL: Asynchronous Digital Subscriber Line.

ADSL Speed Unbalanced upstream/downstream bandwidth Allocate more for downstream traffic. Up to 10 to 1 ratio. Max downstream bandwidth is varied based on the length from access point 6 Mbps – within 3 Kms. 1.5Mbps – more than 3 Kms.

Cable Modem Broadband alternative. Comes with cable TV over Coaxial cable: 2-way. Satellite dish (DSS): 1-way. Coaxial cable Shared medium among neighbors. Send both downstream and upstream via the cable.

Cable Modem Satellite Dish – 1-way Can receive only the downstream. Use normal modem over PSTN for upstream.

Personal Area Network Network within small spaces. Most of them are wireless Wi-Fi (802.11b). HomeRF. Bluetooth. Requirements Small. Low-power consumption.

Wireless LAN Based on Ethernet Standard a – up to 54 Mbps b : WiFi – up to 11 Mbps. Use CSMA/CA Similar to TDMA concept. Characteristics 5 GHz (802.11a) and 2.4 GHz (802.11b). Frequency hopping scheme. Wired Equivalent Privacy (WEP) Similar to SSL.

Frequency Hopping Scheme

Adhoc Configuration Basic Service Set

Interconnection Basic Service Set Extended Service Set

Typical WLAN Configuration

Comparison a Provide more bandwidth. Can cover shorter distance b (WiFi) Low power consumption. Cheaper to produce. In market now.

Bluetooth Wireless technology specifically for: Short range – up to 10 meters typically. 2.4 GHz, Frequency Hoping. Modest performance (721Kbps). Dynamic configurability i.e. ad hoc networking/roaming. Low power, low cost, and small. Well suited to handheld applications. Support for both voice and data.

History of Bluetooth Ericsson, the principal inventor, borrowed the name from Harald Bluetooth (son of Gorm) The King of Denmark circa 900AD United Denmark and Norway Seemed like a good name for uniting many dissimilar devices from different manufacturers

What is Bluetooth Good For? Short-range wireless connectivity within three areas: Data and voice access points Cable replacement Ad-hoc networking

PDA Cell Phone Bluetooth in the Home Cordless Phone Base Station xDSL Access Point Inkjet Printer Scanner Home Audio System Computer Digital Camera MP3 Player

And On the Road Car Audio System Pay Phone & Access Point Hotel Phone & Access Point Headset MP3 Player PDA Cell Phone Laptop

How Does Bluetooth Work? Master Active Slave Parked Slave* Standby* N J F I C D M O P Q Operational States * Low power state

In the Beginning Initially Bluetooth devices only know about themselves Everyone passively monitors in Standby mode No devices are synchronized D A E B C F K J H G I M N L P O Q

Inquiry Discovering Who’s Out There D A Inquiry discovers what other devices are within range 10 meters H M N L P O Q B C F K J G I E H Note that a device can be “Undiscoverable”

D E F H G I K J Paging Creating a Piconet Paging creates a Master/Slave link called a Piconet C M N L P O Q B B A A 10 meters

D Expanding a Piconet (1) Successive Pages can attach up to 7 Active Slaves to a Piconet at one time H B C M N L P O Q E F G I J F J I E G K K A 10 meters

B B J J D H K F I E G Parking To save power and/or to connect to even more devices Active Slaves can be Parked (up to 256 total!) C M N L P O Q A 10 meters

D K F I E G Expanding a Piconet (2) Masters can then attach additional Active Slaves using Active Member Addresses freed up through Parking B J M N L P O Q H C H C A 10 meters

J F I E A G Scatternets D M O Bluetooth devices can participate in multiple Piconets simultaneously creating a topologies called Scatternets B L H K C N P Q

N H K F I E A G J C Advanced Scatternets D M O Scatternets can evolve into extremely complex structures creating a rich fabric of many, many, devices P Q B L

Summary Broadband ASDL. Cable Modem. Personal Area Network Wi-Fi. Bluetooth.

References J. Kurose and K. Ross, Computer Networking: A Top-Down Approach Featuring the Internet, Addison Wesley, And many more.