Multiplex communications – Duplex – Communication over free space
Reexamination Certificate
2000-01-10
2002-02-26
Jung, Min (Department: 2739)
Multiplex communications
Duplex
Communication over free space
C370S470000, C370S474000, C370S342000
Reexamination Certificate
active
06351456
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the implementation of wireless systems in a local telephone loop environment in what is usually called a Wireless Local Loop (WLL). The present invention particularly addresses the air interface and protocols used in the implementation of a Wireless Local Loop.
BACKGROUND OF THE INVENTION
The local loop of a telephone system is what some have termed the “last mile” or the “last 1000 feet”. This local loop is essentially the copper wire that connects the customer premises (i.e., a house or business) to the telecommunications network. The cost of laying down the copper wire can be very expensive (ie, over $1 per foot). Where communities are rural in nature as in some parts of the United States or in developing countries, laying down such an infrastructure can be prohibitively expensive.
As an alternative to installing a wire or cable infrastructure, these rural communities are turning to wireless solutions for their telecommunication needs. However, conventional wireless telecommunication technologies suffer from a number of disadvantages. Often times, because of the quality of the service, modem connections are frequently difficult to establish and maintain. Even where modem connections are possible, data rates are often prohibitively slow.
A further disadvantage of conventional wireless telecommunication technologies relate to their inefficient use of their RF spectrum resources. Subscribers transferring data over the network occupy channels that would otherwise be available for voice communication. In instances in which many subscribers are, for example, accessing the internet, these conventional wireless technologies suffer from a serious degradation in Grade of Service (GOS) resulting in an increase in the percentage of calls blocked (i.e., Erlang B).
These deficiencies are particularly troublesome in view of the fact that data usage is bursty in nature. Analysis of internet data usage indicates that approximately 95-97% of the time, the data network is idle. Furthermore, the aggregate throughput to a user is typically less than 5 kilobits per second.
Therefore, there is a need for a wireless telecommunication system to replace the local loop which more efficiently allocates resources between voice and data communications yet maintains a desirable high GOS.
The following U.S. Patents are made of record for teaching various aspects of wireless telecommunications.
In U.S. Pat. No. 5,239,673, issued Aug. 24, 1993, entitled “Scheduling methods for efficient frequency reuse in a multi-cell wireless network served by a wired local area network,” Natarajan describes communication methodologies that realize an efficient scheduling and frequency reuse in a wireless communications network that is served in a wired network.
In U.S. Pat. No. 4,639,914, issued Jan. 27, 1987, entitled “Wireless PBX/LAN system with Optimum Combining,” Winters discloses a wireless LAN system that employs adaptive signal processing to dynamically reassign a user from one channel to another.
In U.S. Pat. No. 4,837,858, issued Jun. 6, 1989, entitled “Subscriber Unit for a Trunked Voice/Data Communication System,” Ablay et al. disclose a trunked voice/data subscriber that operates in either a voice mode or one of three data modes.
In U.S. Pat. No. 4,852,122, issued Jul. 25, 1989, entitled “Modem Suited for Wireless Communication Channel Use,” Nelson et al. disclose a wireless communication system and, specifically, a modem that communicates digital data with data terminal equipment.
In U.S. Pat. No. 5,603,095, issued Feb. 11, 1997, entitled “Radio System and a Subscriber Terminal for a Radio System,” Uola discloses a wireless local loop system having at least one exchange, at least one subscriber database and base stations, and subscriber terminals communicating with the fixed network via a radio path.
In U.S. Pat. No. 5,555,258, issued Sep. 10, 1996, entitled “Home Personal Communication System,” Snelling et al. disclose a wireless, in-house telephone system designed to provide multi-line telephone operations, allowing the consumer to set up a multiple telephone, multiple line system without having to use wired phone connections running throughout the building.
In U.S. Pat. No. 5,689,511, issued Nov. 18, 1997, entitled “Data Receiver for Receiving Code Signals Having a Variable Data Rate,” Shimazaki et al. disclose a data receiver capable of identifying the code rate of received data and decoding the data at an adequate rate without resorting to a data buffer or a plurality of decoding circuits.
In U.S. Pat. No. 5,504,773, issued Apr. 2, 1996, entitled “Method and Apparatus for the Formatting of Data for Transmission,” Padovani et al. describe a data format which facilitates the communication of various types of data, and data of various rates, to be communicated in a structured form.
In U.S. Pat. No. 5,511,067, issued Apr. 23, 1996, entitled “Layered Channel Element in a Base Station Modem for a CDMA Cellular Communication System,” Miller describes a layered channel software element which supervises the operation of channel element modem resources in a CDMA cellular telephone system that includes forward channels for conveying message and signalling data from a CDMA system base station to mobile units and,reverse channels for conveying message and signalling data from mobile units to base stations.
Wireless local area networks (WLAN) have been available for connecting various computers in a local area. However, such systems have not been appropriate for application on the scale of a local loop. The method of transmitting and receiving signals in WLAN's is not appropriate for the large distances and varied weather conditions encountered in a local loop scenario. Wireless local area networks have the further disadvantage that they cannot carry voice information appropriate for a telephone system.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a wireless telecommunication system that allows individual subscribers in an area of service seamless telecommunications access (i.e., POTS (plain old telephone system), ISDN (Integrated Services Digital Network), data, multimedia, etc.) to a telecommunications network. This system facilitates full voice, data, and fax utilization. This system is designed to replace existing local loops or provide infrastructure for those communities in which no local loop is in place.
These and other objects are achieved by a wireless local loop (WLL) comprising a first interface connecting the WLL to the telecommunications network, a second interface connecting the WLL to a plurality of customer premise equipment (CPE) such as telephones, faxes, and computers, and point to multi-point radio frequency (RF) communications channels connecting the first interface to the second interface. The multi-point RF communication channels provide the user with traffic/bearer data, user control data and radio link specific overhead and control. Traffic bearer data may include the user's encoded voice or data signal. User control data may include ISDN (Integrated Services Digital Controller) D-channel, translated CAS (Channel Associated Signaling) or OAM&P (Operations, Administration, Maintenance & Performance). Radio link overhead and control may include power settings, timing and framing. The present invention makes improvements to the WLL system while not requiring substantial changes to the telecommunications network or the customer premise interface (CPI).
It is a further object of the present invention to is provide concentrated access to the telecommunications network to buildings, campuses, or similar organizations in the area of service that are expected to have high telecommunications traffic demand. This and other objects of the invention are achieved by a capability referred to as “embedded concentrated access” which allows the removal of a specified number of channels from the pool of multi-point RF communication channels and assigns them to the high traffic demand structure. These removed channels are
Easson Michael J.
Hudson Thomas C.
Quinn Patrick Wilton
Struhsaker Paul F.
Jung Min
Nera Telecommunications Inc.
Volentine & Francos, PLLC
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