MMDS and LMDS

The demand for affordable, fast data connections is increasing both in the United States and around the globe. There are several reasons why faster connections are not readily available and affordable. They are a complex mix of entrenched interests of the incumbent connection providers, the high costs of wireline upgrades and the associated slow pace, cumbersome regulations, and tariffs; and the difficulty of forcing more data through already crowded data pipes.

A new wireless broadband point-to-multipoint microwave technology called local multipoint distribution service (LMDS) stands ready to bypass those barriers to readily available broadband connections. In the United States, incumbent connection providers were prevented from owning or controlling the large block of LMDS microwave spectrum in their territory for a period of 36 months (from the auction); consequently, the chances of entrenched interests limiting bandwidth availability are small. In Canada, local multipoint communication service (LMCS) applications from entrenched landline providers were not accepted (see sidebar, "More Communication Choices for Canadians"). The 1 GHz of LMCS spectrum was awarded to newly established companies and consortiums.

LMDS is a wireless broadband service and consequently does not require landline wire upgrades, which makes it affordable when compared with landline technologies. And LMDS is lightly regulated and can be used for two-way transmission of voice, video, and data. Finally, the LMDS spectrum is immense. This large amount of radiofrequency (rf) spectrum allows operators to realize data rates above 1 billion bits per second (bps).

LMDS also provides high-capacity point-to-multipoint data access that is less investment-intensive. LMDS, with its wireless broadband delivery, combined with the significant amount of spectrum allocated, allows for a very high quality communications services. It transmits milliwave signals within small cells. Since it has been tested by the U.S. military and corporate pioneers like SpeedUs.com, Inc., it is undoubtedly a proven technology.

The key to business and consumer acceptance of LMDS as an attractive solution is the affordability and availability of the systems. Because of its point-to-multipoint nature, one LMDS cell with a single hub transceiver can serve hundreds or thousands of simultaneous customers. The affordability of the overall LMDS solution is therefore largely dependent on the cost of the customer premises equipment.

Internationally, governments are working quickly to enable the use of high-gigahertz microwave spectrum for wireless broadband data, voice, and video transport. In many ways, the opportunities internationally are greater than those domestically because of the poor state of the communications infrastructure internationally and the desire of the ministries of telecommunications to move rapidly to make their systems competitive with those in the United States.

LMDS Advantages

• Ease and speed of deployment

• Fast realization of revenue

• Easy network management

• Large bandwidth

• Small cell size

LMDS Disadvantages

• Requires Line of Sight

• Affected by rain, foliage and reflections

• Many cell sites are required

• Multiple cell sites cause interference

• Security concerns

MMDS stands for Mutlichannel Multipoint Distribution Service and this is most commonly termed as Wireless Cable. MMDS is really a wireless communications technology which can be used in high speed networking within the telecoms market. It is frequently utilized rather than a programming reception involving cable connection and is also most favored in India, Brazil, Australia, Pakistan, america, Barbados, Mexico, Russia, Belarus, Lebanon and various areas. Throughout these locations it is primarily used in non-urban parts which happen to have sparse population. This really is caused by a defieicency of regular use cables. Thats usually where laying wires is most popular subsequently MMDS assistance are usually accessible.

MMDS is specified by means of UHF or ultra-high-frequency communications. It operates inside the given FCC accredited frequency. In the usa the FCC is split up into Basic Trading Areas or BTA's which inturn sell the right to transfer MMDS in areas where service providers can be obtained.

MMDS uses BRS bands of 2.1 GHz and also from 2.5 GHz to 2.7 GHz microwave frequencies. Rooftop microwave antennas are widely used to pass on data indicators and also BRS-delivered television reception. Antennas are attached to a transceiver or down-converter which in turn obtains and transmits microwaves signals. They're afterward converted to the frequencies which can be compatible with TV tuners. This is similar to the way indicators are transformed into the frequencies for satellite dishes but instead these are suitable for TV coaxial cables.

The MMDS band is afterward segregated into channels of 33 6 MHz. Because of this these kinds of people can own a number of other channels, radio, multiplex televisions along with Internet data. Digital cable channels are then capable of regulate 64QAM as well as 30.34 Mbps together with 256QAM modulation having 42.88 Mbps.

MMDS Disadvantages

• Limited two way capabilities (upstream bandwidth is limited)

• Shadowing and interference prevents ubiquitous coverage

• Normal radio security concerns

MMDS vs. LMDS

• Supports high bandwidths but gets affected by
  rain, foliage and reflections
• Requires Line of Sight conditions to serve
• Operates in smaller radius and hence more
  number of cell sites required for a city coverage
• Supports relatively lower bandwidths but does
  not get affected by the rain or foliage conditions
• Also works in Near Line of Sight (NLoS)
  conditions
• Supports larger coverage area hence few cell
  sites required to cover a city

Originally designed for wireless digital television transmission, LMDS and multipoint microwave distribution system (MMDS) were predicted to serve wireless broadband subscription television needs. MMDS is also a broadband wireless communications service that operates at lower frequencies. Usually, LMDS operates at frequencies above the 10-GHz range and MMDS at frequencies below the 10-GHz range. Later on they were extended to offer other interactive services.

Sources:

http://www.networkcomputing.com/netdesign/bb3.html

http://www.eetimes.com/electronics-news/4039196/LMDS-MMDS-race-for-low-cost-implementation

http://www.networkcomputing.com/netdesign/1223wireless1.html

http://quantumwimax.com/index.php?page=History-of-Wimax

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