Metropolitan wide area network

Details Metropolitan wide area network Metropolitan wide area network

1998-07-21

2004-06-29

Ton, Dang (Department: 2666)

Multiplex communications

Communication over free space

Having a plurality of contiguous regions served by...

C370S310000, C370S395510, C370S396000, C370S401000, C370S468000, C455S003030, C455S422100, C375S212000

Reexamination Certificate

active

06757268

ABSTRACT:

BACKGROUND
1. Technical Field
The present disclosure relates to a metropolitan wide area network for telecommunication systems. In particular, this invention relates to the integration of a wireless point to multi point system operating in the millimeter microwave radio range with an intelligent metropolitan area broadband backbone network to enable a variety of enhanced voice, broadband data and multimedia telecommunication services.
2. Description of Related Art
In the art, point-to-point narrow band, point to multi point narrow band and point to point broadband fixed wireless systems are generally known. Point to multi point radio technology is also a known technology which has been generally used for narrowband communications, such as voice. Narrow band systems are typically systems that are capable of generating at or below 1.544 megabits per second of data in a single circuit or channel, whereas broadband systems are capable of generating data rates above 1.544 megabits per seconds per circuit or channel. While narrowband “point to multi point” systems have been used for voice communications, point to multi point systems have not been generally applied to broadband telecommunications networks.
Today's narrowband point to multi point systems can aggregate a group of up to twenty four 64 kilobits per second channels together in what is called a “T
1
line.” However, this T
1
line is still considered a narrowband facility when it is used to support multiple voice channels. Narrowband point to multi point systems have also been in use in Europe for voice telephone networks for several years.
Point-to-point broadband technology is also well known. Above 18 Gigahertz (millimeter microwave frequencies), and especially in the 37 Gigahertz or “GHz” to 40 GHz range (typically referred to as “38 GHz”), point-to-point broadband wireless systems are in use. When such broadband wireless links are engineered properly, their performance is functionally equivalent to that of fiber optic telecommunications.
Fixed wireless technology at frequencies of 18 GHz and above is gaining popularity as means for transmission of telecommunication services because of its low cost, rapid installation and ease of operation. Connecting two sites with point-to-point wireless service largely consists of installing roof top antennas on the top of two buildings, with the accompanying indoor equipment. Physical wires do not have to be connected between the buildings, representing a significant advantage over copper or fiber technology. Bringing fiber or copper to buildings entails tremendous labor and other costs associated with digging up streets, obtaining permits, etc. Because the deployment of broadband fixed wireless systems does not require civil construction in most instances, it is thus faster and more economical to install than traditional methods of “last mile” interconnection in metropolitan area telecommunications networks.
Current fixed wireless technology operating at frequencies of 18 GHZ and above (millimeter microwave wave) has a number of characteristics that make it an attractive commercial telecommunications transport medium. Fixed millimeter microwave wireless technology provides a high bandwidth path for voice, data, multimedia and video. Current technology permits link distances of up to five miles. Since all millimeter microwave propagation is subject to rainfall degradation, actual distance is a function of geographical location or “rain region.” In climates where heavy rainfall is common, shorter link distances may be required to achieve performance and availability equivalent to that of fiber.
Millimeter microwave radio propagation generally requires unobstructed line-of-sight transmission. In practice, small diameter antennas are mounted on office building rooftops, and in some cases in office building windows. The size of the antennas vary according to the selected frequency band, but typically range from 12 to 24 inches in diameter. Manufacturers indicate mean time between failure (MTBF) statistics in excess of 10 years for the radio and modem components, indicating that the hardware is highly reliable. Current fixed wireless millimeter microwave technology is therefore ideally suited for high availability broadband point-to-point commercial voice and data applications ranging from 1.544 Megabits per second (T
1
) to 45 Megabits per second (DS3) capacities.
One example of a typical wireless point-to-point broadband commercial application is the interconnection of multiple servers in a campus local area network (LAN). Another such application is metropolitan wide area networking. Here multiple campus LANs within the same city are interconnected via wireless facilities operations at millimeter wave frequencies. Dedicated access to inter-exchange carriers (IXCs), Internet Service Providers (ISPs) and other alternate access arrangements are common point-to-point business applications for millimeter wave wireless links. For example, cellular and personal communication services (PCS) operators may deploy high availability wireless facilities in a millimeter microwave range in their backbone networks to support back haul between antenna sites, base stations and mobile telephone switching offices (MTSO's). Wireless point-to-point millimeter microwave technology is also being used to provide mission critical protection channels and other point-to-point alternate routing where extension is required from a fiber network to a location that is not served by fiber. Finally, interconnection with the public switched telephone network (PSTN) for the provision of local dial tone by competitive local exchange carriers (CLECs) utilizing point-to-point millimeter microwave wireless technology is becoming increasingly popular.
FIG. 2
illustrates a basic point-to-point wireless facility providing customer interconnection to services. This connection will support broadband (data, video etc.) and narrowband (voice) applications. A customer building is shown as
200
and may contain multiple tenants. It is connected to another building
202
that houses a telecommunications network switch
203
. These buildings are connected by a wireless link between two roof top antennas: one antenna
204
at the customer building, the other antenna
205
at the building housing the switch
203
. The bandwidth of this connection could be up to 28 T
1
circuits, or DS3 (45 Megabits per second). The switch
203
connects to the PSTN
206
, or public switched telephone network for local service, and to long distance networks
207
for long distance service. The switch
203
is also able to provide dial up access to the Internet
208
.
FIG. 3
is a representation of an exemplary system defined channelized spectrum allocation plan suitable for use in millimeter microwave frequencies. For example, the FCC spectrum allocation plan for an exemplary millimeter microwave band at about 38 GHz consists of
14
total channels. Each channel is 100 MegaHertz (MHZ) in bandwidth. Each 100 MHZ channel consist of two 50 MHZ sub channels, one sub channel to transmit and the other sub channel to receive. These two 50 MHZ sub channels are separated by 700 MHZ of spectrum. As shown in
FIG. 3
, sub channel
1
A is 50 MHZ wide and it is a transmitting channel, whereas sub channel
1
B is 50 MHZ wide and it is a receiving channel. Sub channel
1
A is separated from sub channel
1
B by 700 MHz. This band plan yields 14 channels (1400 MHZ or 1.4 GHz) of spectrum in the FCC allocated 38 to 40 GHz range. Similar frequency channel allocations can be established (and planned) in other millimeter microwave frequencies as well, including 24, 28 and 40 GHz in the United States and 23 and 26 GHz in Europe. For example, in the 28 GHz LMDS band (in the United States) spectrum is largely allocated in a single 850 MHZ wide spectral block. However, such a block spectrum allocation can be subdivided into system defined channels, to achieve the same result to that shown in FIG.
3
.
Referring to
FIG. 4
, a basic spectrum management problem associa

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