Multiplex communications – Communication over free space
Reexamination Certificate
1998-07-09
2003-09-30
Chin, Wellington (Department: 2664)
Multiplex communications
Communication over free space
C370S395430
Reexamination Certificate
active
06628627
ABSTRACT:
BACKGROUND
1. Technical Field
The present disclosure relates generally to wireless communications systems and more particularly relates to a wireless system utilizing millimeter microwave radio frequencies to provide symmetrical, bidirectional broadband telecommunication and multimedia services to remote terminals which distribute the services about the remote terminal location.
2. Description of Related Art
There is an ever-increasing demand for higher bandwidth, multi-service telecommunications to both commercial facilities and residential homes. This demand is driven by the advent of telecommuting, pay-per-view television programming, video-on-demand, and Internet commerce. Services such as these have varied data-types (e.g. voice, broadband multimedia, and video) with widely varying traffic patterns, “Quality of Service (QoS)” constraints and bandwidth requirements. As the need for higher bandwidth and more varied services effects a greater number of homes, telecommunication service providers will be tasked with providing the residential home consumer with common access to these services in a fast, cost-effective and easy-to-maintain way.
Fixed wireless technology 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 wireless service may largely consist of installing roof top antennas on the top of the sites and connecting the antennas to the accompanying indoor equipment. Physical wires do not have to be connected between the sites, representing a significant advantage over copper or fiber technology. Because 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 of offices and homes to a telecommunications network.
Another reason for the growing interest in millimeter microwave radio technology is performance. When broadband wireless links are engineered properly, the links provide a high-bandwidth path for voice, narrow band data, broadband multimedia content and video whose resulting performance can be functionally equivalent to fiber optics. In addition, current technology permits link distances up to five miles.
Providing traditional telecommunication (i.e., telephony) services to residential homes across wireless systems is well known. However, supplying wireless services such as broadband multimedia and video to customers' homes has more recently begun to emerge and develop. For instance, Multi-point Distribution Systems (MDS) and, more recently, Multi-channel Multi-point Distribution Systems (MMDS) provide wireless television service to households having MDS or MMDS compatible equipment. The initial so-called “wireless cable” systems operated within the MDS frequency range of 2150 MHZ to 2162 MHZ. Limited television programming over one or two channels was provided under the MDS frequencies. With the advent of MMDS, operating in a frequency range of 2500 MHZ to 2686 MHZ, a plurality of channels may be simultaneously provided to a microwave antenna located on the rooftop of a customer's home.
Emerging simultaneously with the development of television programming systems, as described above, has been the need to provide feedback from the customer to the program delivery source such as, for example, pay per view systems. Initially, with respect to wireless cable systems, no such return link existed and the customer was left to rely on making a phone call to the programming source in order to communicate his programming choices. Television set top units were later manufactured which provided standard telephone hookups for sending data back to the programming provider's billing computer. However, connecting a telephone line to every set top unit is costly.
Instructional Television Fixed Service (ITFS) response frequencies (2686.0625 MHZ to 2689.8125 MHZ) have been considered for use as return link frequencies by the FCC. However, due to the fact that the receive (MMDS) and transmit (ITFS) frequencies are so close to one another, separate receive and transmit antennas were initially required to implement such an approach. This increased the cost and complexity of such a solution.
A system for providing a forward wireless programming path as well as a return over-the-air information/data path which attempts to overcome the above problem is proposed in U.S. Pat. Nos. 5,394,559 and 5,437,052 (both issued to Hemmie et al.). The Hemmie et al. systems provide bidirectional over-the-air transfer of programming and information/data between a common transmission point such as a tower and each of a plurality of remote locations such as consumers' houses. This is accomplished by utilizing the same microwave antenna at a consumer's house for receipt of programming and for transmission of data. A bidirectional converter and dual polarity isolated feed system is utilized to receive and to “down convert” the MMDS microwave programming signals and to “up convert” and transmit the ITFS response microwave data signals.
However, while such a system provides a bidirectional transfer path, it is to be appreciated that both the forward transmission path and, more severely, the return transmission path, are limited in their service-providing capacity and the system architecture fails to provide compatibility with services other than those which are television programming related.
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 that has been generally used for narrow band 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 narrow band 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.
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. In this case, multiple campus LANs within the same city are interconnected via wireless facilities. Dedicated access to inter-exchange carriers (IXCs), Internet Service Providers (ISPs) and other alternate access arrangements are.common point-to-point business applications for wireless links. In the millimeter microwave radio range, cellular and personal communication services (PCS) operators may deploy high availability wireless facilities in their backbone networks to support back haul between antenna sites, base stations and mobile telephone switching offices (MTSO's). Wireless point-to-point technology is also 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 wireless technology is becoming increasingly popular.
Referring to
FIG. 1
, a basic spectrum management problem associated with the use of prior art point-to-point wireless systems in a metropolitan area is shown. Because buildings are close to each other in a metropolitan area, the broadcast of information over wireless links may overlap, making the use of the same channel (
1
A/
1
B) in contiguous systems impossible. In
FIG. 1
, one antenna from one building is transmitting its signal to the antenna of the intended receiver, but a portion of the signal is also being received by the antenn
Ackerman David
Zendle Allan M.
Chin Wellington
Ohlandt Greeley Ruggiero & Perle L.L.P.
Pham Brenda
Winstar Communications Inc.
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