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).

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.

On February 18, 1998, the Federal Communications Commission (FCC) commenced the auctions for 1.3 GHz of lightly regulated LMDS radiofrequency spectrum in the 28- to 31-GHz range. In March 1998, the auctions were completed successfully, raising almost $800 million. Several years of auction delays have created a pent-up demand for LMDS operators, who are very interested in earning a return on their investment by providing reliable broadband wireless services to customers in as short a time frame as possible.

According to the Strategis Group, it estimated that the total LMDS equipment expenditures for the United States alone would be $551 million in 2001 and grow to $4.77 billion in 2005. These numbers include both hub and subscriber expenditures.

With this in mind, this chapter presents a very detailed discussion on LMDS. With an introduction devoted to LMDS and then a discussion on fixed wireless broadband networks, this chapter looks into different ways fixed wireless broadband communication can be achieved and then gives a detailed description on the various wireless broadbands available for communication. It also discusses technical and design issues involved with LMDS.

Underlying Technology Overview

Local multipoint distribution service (LMDS) is a broadband wireless point-to-multipoint communications system that provides reliable digital two-way voice, data, and Internet services. The term local indicates the signal's range limit. Multipoint indicates a broadcast signal from the subscribers. The term distribution defines the wide range of data that can be transmitted, data ranging anywhere from voice or video to Internet and video traffic.

Note: Later in this chapter the emergence of LMDS shows why it is good at transmitting such a wide variety of data.

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.

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.

Note: Multipoint microwave distribution system, also known as multichannel multipoint distribution system and wireless cable, is another wireless broadband technology for Internet access. MMDS channels come in 6-MHz chunks and run on licensed and unlicensed channels. Each channel can reach transfer rates as high as 27 Mbps (over unlicensed channels: 99 MHz, 2.4 GHz, and 5.7 to 5.8 GHz) or 1 Gbps (over licensed channels). MMDS is a line-of-sight service, so it will not work well around mountains, but it will work in rural areas, where copper lines are not available.

Before discussing LMDS, it is necessary to understand the importance of using wireless broadband technology for local-area networks (LANs) first and then to look at the different methods available for wireless broadband communications.