This document defines and compares two types of wireless local loop (WLL) technologies: Local Multipoint Distribution Service (LMDS) and Multichannel Multipoint Distribution Service (MMDS). LMDS operates above 20 GHz and provides high-speed broadband, while MMDS operates between 2.1-2.7 GHz and provides lower bandwidth but stronger signals over longer distances. Both can provide voice, data and video services as alternatives to wired local loops. Key differences are that LMDS supports higher data rates over shorter ranges while MMDS has a larger cell size and is more suitable for large networks.

1. Prepared by,
SANJAY C. CHAURSIYA
ELECTRONICS AND COMMUNICATION
GOVERNMENT ENGINEERING COLLEGE,
BHUJ
PAYAL R. PANDYA
ELECTRONICS AND COMMUNICATION
GEC- BHUJ

2. Contents
 What is Wireless Local Loop (WLL)
- Definition
Access technology
Features
• Types of Wireless local loop (WLL)
1) Local Multipoint Distribution Service (LMDS)
- Definition
- Advantages and Disadvantages
2)Multichannel Multipoint Distributed Service (MMDS)
-Definition
-Advantages and Disadvantages
 Comparison between LMDS and MMDS.
 Future scope
 Manufacturer of WLL

3. What is Wireless Local Loop
 In a telephone network a Wireless Local Loop is a generic
term for an access system that uses a wireless link to
connects subscribers to the local telephone station in place
of conventional copper wire.
 In Fixed Wireless Access Systems the Wireless Local
Loop is popular, WLL is also called as Fixed wireless loop.
 The function of a WLL is to make primary access to
local telephone station using wireless link.

4. WIRELESS LOCAL LOOP
 In the WLL system there are two concepts namely
 Narrowband WLL – offers a replacement for existing
telephony services.
 Broadband WLL – provides high-speed two-way voice
and data service.
 Thus, WLL is the best system to handle high data traffic
in the local loop system.

5. How its works
 WLL, which stands for Wireless Local Loop that
connects subscribers to the PSTN using radio signals
as a substitute for copper for all or part of the
connection between the subscriber and the switch.
 WLL phones in homes, offices or even boats connect
with a wireless system in a manner similar to that of
CDMA cell phones.

6. Configuration of WLL

7. Access Technology
 Frequency Division Multiple Access
 Code Division Multiple Access
 Time Division Multiple Access
 The one being used in India is CDMA.

8. Features
 Better quality of service
 Compatible with other cellular technologies
 Scalability

9. Advantages of WLL
 The cost of wireless equipment is less.
 Easy installation
 They have good scale of installation.

10. TYPES OF WLL
 There are two type of WLL technique available. They are
i. Local Multipoint Distribution Service (LMDS)
ii. Multichannel Multipoint Distribution Service(MMDS)

11. Local Multipoint Distribution Service
 Local Multipoint Distribution Service (LMDS) is the
broadband wireless point-to-multipoint communication
system operating above 20 GHz that can be used to provide
two-way voice, data, video services and Internet.
 Fixed broadband technology that can provide a wide variety
of wireless services
High-speed Internet access
Real-time multimedia file transfer
Remote access to local area networks
Interactive video, video-on-demand, video conferencing
Telephone service

12. LDMS TRANSMISSION

13. Advantages and Disadvantages
 Advantages
1. Easily developed
2. Cost effective
3. High data rate
4. scalable architecture
 Disadvantages
1.The drawback of LMDS is that it needs large number of base
stations because of its short range of operation frpm the base
station.

14. Multichannel Multipoint Distribution
Service
 MMDS is a broadcasting and communications service that
operates in the ultra−high−frequency(UHF) portion of the radio
spectrum between 2.1 and 2.7 GHz. MMDS is also known
as wireless cable.
 In MMDS, a medium−power transmitter is located with an
Omni−directional broadcast antenna at or near the highest
topographical point in the intended coverage area. The
workable radius can reach up to 70 miles in flat terrain.
 Fixed broadband wireless technology similar to LMDS.
 Can transmit video, voice, or data signals at 1.5 to 2 Mbps
downstream and 320 Kbps upstream.

15. MMDS Structure

16. Advantages and Disadvantages
 Advantages
1. High signal strength
2. Cell size is small
3. Less cost than LMDS
4. Larger wavelength
 Disadvantages
1. Physical limitations
The transmitted power as the FCC did not allow the power
transmitted of the base station serving area that is more than
50 km.

17. Comparison between LMDS MMDS
• Both are used for TV and 2-way internet service using fixed
wireless access.
 Due to lower RF frequency range MMDS provide lesser BW
compare to LMDS.
 LMDS offers higher data rates.
 MMDS signal can cover long distance and hence used in large
cell network scenario. LMDS signal can cover short distance
from Base Station equipments.
 Due to larger wavelength MMDS signals are less susceptible
to rain and absorption losses compare to shorter wavelength
LDMS signal.

18. Future Scope of WLL
 CDMA based WLL
 As the cost of mobile technology decreases, it is
becoming more and more economic to install 'fixed'
lines using WLL.

19. Manufacturers of WLL
 Airspan
 Alvarion
 Cambridge Broadband
 P-Com
 Sony Ericsson
 SR Telecom
 Intracom Telecom

20. Question
 What is the primary difference between wireless
local loop and a CDMA cell phone?
 Wireless local loop phones are for use in a relatively
fixed location and can use A/C instead of batteries.