Telecommunications – Carrier wave repeater or relay system – With frequency conversion
Reexamination Certificate
1999-01-11
2002-06-11
Vo, Nguyen T. (Department: 2682)
Telecommunications
Carrier wave repeater or relay system
With frequency conversion
C455S560000, C455S562100
Reexamination Certificate
active
06405018
ABSTRACT:
BACKGROUND
As wireless communication services become more popular, the need for providing wireless communication services where those desiring such services may be located also increases. Moreover, such wireless service demand increases introduce problems in providing enough capacity in areas where such wireless communication services are provided.
In order to provide for free roaming wireless telephone communications wireless cellular telephone networks have been deployed throughout many populated areas. Such systems rely on the use of predefined areas of channel reuse in order to utilize a limited amount of radio frequency spectrum in serving a particular capacity of wireless communications. Accordingly, radiation of a particular communication channel is limited to within a particular area associated with a cellular base transceiver station (BTS).
Such systems generally suffer from coverage gaps or holes where a particular BTS is unable to radiate a signal or channel with attributes suitable for use in conducting communications over the network due to such obstructions as large buildings. Often it is difficult or impossible to sufficiently fill in these gaps with signals radiated from adjacent BTSs of the cellular network because of resulting problems with overlapping radiation patterns in areas unaffected by the obstruction, multiple obstructions such as buildings in a metropolitan area blocking signals from multiple adjacent BTSs, and the like.
Moreover, often the areas associated with such gaps in communication service coverage are areas of more dense congregation of those desiring such wireless services. For example, large numbers of persons desiring to use wireless mobile subscriber units (MSU) may be present within urban buildings which are shaded from signals radiated from BTSs of a communication network by the structure of the building itself or other buildings located in the communication path.
Similarly, although within an area providing suitable communication with a BTS of a cell encompassing such a building, the concentration of persons desiring wireless communication services may demand capacity not available from such a cell. Accordingly, enhanced capacity may be provided by disposing a cell, or microcell, to service such a concentration, i.e., a cell disposed to service communications associated with MSUs located within or near a high rise office tower.
Accordingly, solutions have been offered which deploy antennas, coupled to a transceiver of a communication network, within buildings in order to provide wireless communication services therein. However, such prior art solutions have often been limited to combining the signals of all or a plurality of the antennas disposed in the building and providing the combined signals to the transceivers. Such an approach suffers from disadvantages such as the signal provided to each transceiver includes the noise initially present on only one or a few antennas, such as a particular interfering signal from outside the building, because the antenna signals are combined. Moreover, the sum of such noise being present on multiple ones of the antennas can result in the noise exceeding limits for an acceptable carrier to interference (C/I) ratio. Accordingly, the number of such antennas is generally limited to a small number in order to maintain a desired signal quality level. Additionally, due to the signal loss issues associated with the antenna feed network of these prior art systems, the deployment of these prior art antennas is limited to relatively short distances from the associated transceiver.
In order to overcome some of the above described problems, other prior art systems have utilized transceivers distributed throughout the communication coverage area, i.e., deployed throughout a building in which communication is to be provided. However, such a solution presents substantial disadvantages also. Specifically, by definition such a solution requires multiple, and often expensive, transceivers to be deployed in order to provide communications in more than one area of the building. Moreover, the deployment of multiple transceivers capable of communicating on a same channel in order to provide this channel within multiple portions or an increased portion of the area serviced involves the inefficient use of such transceivers and/or channels. Furthermore, the use of such transceivers does not readily provide capacity for multiple simultaneous communications within a particular area without deploying multiple ones of the transceivers to provide communications within each such area, thus further aggravating inefficiencies associated with the deployment of transceivers throughout the service area. Additionally, the distributed deployment of transceivers substantially complicates the control mechanism required to operate such a communication network in addition to requiring added communication paths including control signal paths for each transceiver.
Accordingly, a need exists in the art for a wireless communication system adapted to provide communication within a limited area of service, such as within a building, wherein antenna signals are maintained distinct while providing efficient use of transceiver equipment, including allowing for the use of an assigned channel to “follow” the movement of a unit in communication with a particular transceiver as the unit moves from the coverage area of one antenna to that of another and/or providing dynamic capacity availability to address capacity demand changes within the area of service. A further need exists in the art for such a system to be adapted to utilize a number of antennas sufficient to provide a desired cumulative area of coverage even where physical barriers, such as floors or walls of the aforementioned building, prevent each individual antenna from providing coverage within a substantial portion of the total area to be covered.
Additionally, a need exists in the art for the wireless communication system to be adapted to require a minimum of signal paths as between the antennas and transceiver equipment in order to provide the desired communications. A still further need exists in the art for such signal paths to allow for the disposal of antennas a substantial distance from transceiver equipment coupled thereto.
SUMMARY OF THE INVENTION
These and other objects, features and technical advantages are achieved by a system and method which utilizes a plurality of antennas strategically deployed throughout an area to be provided wireless communication service and coupling such antennas to transceiver equipment, i.e., radios, of a BTS or BTSs such that a particular antenna may be selected for communication of a particular transceiver signal. Accordingly, the transceivers of the BTS may be centrally located and thus easily centrally controlled and/or coupled to additional components of the communication network such as a public switched network (PSN) or mobile switching office (MSO). Moreover, as transceivers of the BTS may selectively communicate via ones of the plurality of antennas, efficient use may be made of such transceivers. For example, a single transceiver may be deployed for each channel of a plurality of channels utilized by such a communication system and yet communications may be established and maintained on a particular channel throughout all or a substantial portion of the coverage area utilizing only a single transceiver associated with this particular channel.
The preferred embodiment of the present invention utilizes switched beam or smart antenna technology in order to provide a plurality of antenna beams throughout the area to be covered which may then be selectively utilized by ones of the BTS radios. Accordingly, directional, either fixed beam or adaptive array, antennas are placed throughout the area to be covered, such as by deploying multiple antennas on each floor of a building and directing their antenna beams to illuminate substantially only areas within the building. As MSUs, or other wireless communication units including fixed subscriber unit
Reudink Douglas O.
Shen Donglin
Shuman Robert N.
Fulbright & Jaworski L.L.P.
Metawave Communications Corporation
Vo Nguyen T.
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