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Chapter 2: TechnologyIntroduction
There is a plethora of technology issues that a LMDS operator needs to factor into the design and ongoing operation of the system. The technology decisions are important also for decisions involving the implementation of various services and functions from the LMDS operators platform. Technology decisions also are involved when evaluating competitive service offerings and for the determination of niche markets, features, and services that can be used for the LMDS operators' advantage.
This chapter attempts to address many of the technology issues that a LMDS operator is often confronted with and will need to address when making decisions regarding which technology or technologies to utilize for a LMDS, MDS or FWPMP system. The technology topics will be covered in a depth that will provide general understanding of the various commonality and differences between the vast array of platforms that have to be used.
In particular parts of any LMDS network, the PTT/CLEC can be a competitor, service provider, partner, customer, or all of them combined. In many cases, the LMDS operator can complement a local PTT/CLEC or ISP in the service delivery. In fact, most PTT/CLECs utilize a variety of transport platforms to deliver specific services to a diverse customer base.
The reference to analog in wireless can and does takes on a multitude of meanings that invoke different responses, depending on the situation and system it is applied or referenced to.
Analog communication references any communication that does not utilize a digital modulation format to convey its information-voice. Specifically, a form of analogcommunication is the AM or FM station that you listen to in your vehicle or home. Typically, the term "analog" usually refers to an FM-modulated signal. When people reference analog channels in a cellular communication system, they are referring to the 30kHz AMPS channel that was and is used prior to the advent of digital radio platforms. It must be stressed that although voice is being transported as analog, the system will utilize digital modulation for conveying control and subscriber information.
For a PTT/CLEC, analog is typically the local loop where voice is delivered over copper wire from the wiring center to the residence. This is important for an LMDS operator if the service offering involves voice, POTS, or interfaces to a PBX that has an analog line card, to mention two quick examples.
Digital or digital modulation is prevalent throughout the entire wireless industry. Digital communication references any communication that utilizes a modulation format that relies on sending the information in any type of data format. More specifically, digital communication is where the sending location digitizes the voice communication and then modulates it. At the receiver, the exact opposite is done.
Data is digital, but it needs to be converted into another medium in order to transport it from point A to point B; more specifically, between the base station and the host terminal. The data between the base station and the host terminal is converted from a digital signal into an RF energy whose modulation is a representation of the digital information that enables the receiving device, base station, or host terminal to properly replicate the data.
Digital radio technology is deployed in a cellular/PCS/SMR, and specifically in an LMDS system to increase the quality and capacity of the wireless system over its analog counterpart. The use of digital-modulation techniques enables the wireless system to transport more bit/Hz than would be possible with analog signaling utilizing the same bandwidth. There are, of course, many different digital modulation schemes utilized in LMDS, but the more common ones are the following:
The data rate that each can support increased with modulation complexity, but there is a tradeoff that is made. With increased modulation complexity, the range of the site is reduced, resulting in higher capital deployment costs at the beginning of the systems life cycle.
For LMDS, there are several competing digital techniques that have been or are being deployed. Each of the technologies has advantages and disadvantages that need to be understood prior to their implementation...