Chapter 3: Introduction of Wireless and Mobile Systems (Part II)

1. Chapter 3:Introduction of Wireless and Mobile Systems (Part II) Associate Prof. Yuh-Shyan Chen Dept. of Computer Science and Information Engineering National Chung-Cheng University

2. Outline • PCS • WLL (Wireless Local Loop) • LMDS (Local Multipoint Distribution System)

3. PCS • Personal communication service • Developed out of the need for more capacity and design flexibility than that provided by the initial cellular systems • PCS • Narrowband service • Offers many enhanced data service • The data throughput remained at 9.6 kbit/s

4. The Challenge of wideband PCS • Wideband PCS for offering high-speed data has not yet been deployed • The obvious issue • is coexistence with the current PCS system • The need for more base station due to reduced sensitivity cased by increased bandwidth • Is the offering of subscriber units that can act as dual band units

5. PCS • PCS band was broken into A, B, C, D, E, and F blocks • A, B, C blocks involved a total of 30 MHz, while the D, E, and F blocks are allocated 10 MHz. • PCS license boundaries are defined as metropolitan trading areas (MTAs) and basic trading areas (BTAs). • The MTA has several BTAs within its geographic region

6. PCS • There are a total of 93 MTAs and 487 BTAs in USA • All the frequency allocations are duplexed

7. U.S. cellular spectrum chart

8. PCS spectrum allocation

9. WLL (Wireless Local Loop) • The WLL system, is different from the cellular or PCS systems in its application, which is fixed. • The fixed service is often referred to as a local multipoint distribution system (LMDS) or • A fixed wireless point-to-multipoint (FWPMP) system • In many case, WLL is the same as LMDS and FWPMP in its deployment and application

10. WLL system • WLL is most applicable in areas where local phone service is not available or cost effective • WLL is a system that connects a subscriber to the PTSN or PTT (local telephone company) using a radio link as its transport medium instead of copper wires

11. WLL Example

12. More common types of WLL systems • Cellular • PCS • Cordless telephone (CT-2) • Digital European cordless telecommunication (DECT)

13. WLL • For a developed country • WLL allows for use of a cordless phone as an extension of the house phone or private branch exchange (PBX), which is an added convenience • For a emerging country • Has areas without any access to a communication service • The use of WLL can create profound changes because it is quicker, easier, and less expensive to install than a regular landline system

14. LMDS (Local multipoint distribution system) • The LMDS is a unique wireless access system whose purpose is to provide broadband access to multiple subscribers in the same geographic area. • The LMDS utilizes microwave radio as the fundamental transport medium and is not really a new technology

15. LMDS • The LMDS system allows multiple users to access the same radio spectrum • The LMDS is a wireless system that employs cellular-like design and reuse with the exception that there is no handoff • Multiple subscribers (customers) surrounding an LMDS hub or base station

16. Generic LMDS system

17. LMDS • The LMDS is a point-to-multipoint system where multiple subscribers can access the same radio platform utilizing both a multiplexing method as well as queuing • Through overbooking • There are QoS issues and specific service delivery requirements

18. LMDS • Provide vastly greater bandwidth requirements and service to a larger population than point-to-point system utilizing the same spectrum can

19. The key differences between mobile systems and LMDS • The ubiquitous coverage is not required • Operator only provide service where the customers are actually located thereby maximizing the capital infrastructure effectiveness and minimizing operating expenses

20. Example: Multiple Customer Location/Dwelling Unit