MCT-LMDS/MMDS Network Solution

Broadband point-to-multipoint, which can deliver broadband wireless access to users without fiber services, used to be considered the wave of the worldwide telecoms market. That future took a long time to take off, and today, the two major forms of broadband point-to-multipoint -- local multipoint distribution service (LMDS) and multichannel multipoint distribution service (MMDS) -- are barely active.

LMDS:

LMDS uses fixed line-of-sight (LoS) transmission from a roof with a base station to subscriber roof stations. Initial proponents claimed a throughput of 45M across a 4.8km radius -- good enough to offer broadband in urban areas without digging up the streets.

The United States government allocated the 28GHz to 31GHz spectrum for LMDS and in 1998 auctioned off more than 800 local licenses for a total of about $580 million. Some LMDS carriers used different bandwidths under previously purchased licenses.

MMDS:

The problem with MMDS was a combination of economics and technology.

MMDS requires the use of tall LoS antennas with a radius of more than 48km to provide consumers or small businesses with broadband access. Additionally, service prices went up due to competition from DSL and cable services, which set the price at about $50 per month, and from satellite service, which capped prices at about $80 a month. With hardware listing at $1,000 per customer, the service did not make economic sense.

Features:

•  IP Wireless-

•  Self-installation

•  Plug-and-play

•  No LoS limitations

• Portability to enchance customer acceptance and use of inexpensive modem.

•  Smaller antennas

•  Network Scalablility

•  Labor costs

IP Wireless is offering a second-generation system, based on 3G UMTS wireless technology.

 Each IP Wireless base station offers 9M, typically 8M downstream and 1M upstream. Each can support 700 to 1,000 users. There are typically three stations per tower in urban areas, covering 120 degrees each. The price is less than $300 per user.

The modem is the size of a PDA and sells for less than $500.The price may fall to below $250 as 3G components become plentiful. Not only is the unit portable so that the user can relocate with it, it also works while driving down the highway. A user can buy a modem at a store, take it home, plug it into a PC, go online, give the network a credit card number and be online.

OFDM system optimized for broadband wireless has been delivering 13.6M to an indoor receiver 3.2km from the base station. It can offer seven channels per base station and three stations per antenna, or about 300M of capacity.

Future  in 3G networks?

LMDS is still in use in various places, but the main talk about its future revolves around its possible use as an easily installed backhaul carrier in future 3G networks.

LMDS technology is now in its third generation and thus, works reliably in multipoint setttings. Its glory days may still be ahead.

Third generation LMDS uses TDD and TDMA for maximum throughput, as well as adaptive modulation for maximum range.

 Ensemble launched its LMDS products about a year ago. "I think the idea (of LMDS) will come back even stronger, very soon, even later this year, but everyone is talking about mobile backhaul since that market is moving. "But there is no faster, cheaper and better way to hook up a city than broadband wireless when connected to fiber."

http://www.wicomtech.com