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