Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Patent
1997-07-03
1999-12-14
Kuntz, Curtis A.
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
455450, 455517, 370337, 370442, H04B 1700
Patent
active
060029196
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a wireless local loop system comprising base stations and an access network node which connects the cordless terminal equipments to the exchange of the fixed network. The system especially comprises an air interface between the cordless terminal equipment and the base station, the interface being mainly in accordance with the GSM mobile system, wherein a multiframe of a traffic channel TCH consists of 26 TDMA frames, at least one of which is a frame of a slow associated control channel (SACCH) in the time slot of which the terminal equipment (T) transmits measurement information to the base station and the base station (BS) transmits control information to the terminal equipment, and one frame is an IDLE frame.
When a telephone network is being built, the installation of the subscriber lines between the exchange and the subscriber equipments is not only considerably expensive but also requires a great deal of time. Usually the network of subscriber lines is formed in such a way that twin cables beginning in several subscriber equipments are supplied to a distribution frame, and cables originating in several crossbar switches are combined in another distribution frame the cable of which is supplied to the exchange. The signalling interface between the exchange and the subscriber lines is standardized, and it is either an interface of two-wire analogous subscriber lines, a multiplexer interface according to Recommendation V2 of the CCITT, or a message-based multiplexer interface according to Recommendation V5.1 of the ETSI. Altering fixed subscriber lines is troublesome, and maintenance costs especially in areas where the subscriber lines are overhead lines can be considerable. A solution to these problems is replacing the fixed lines between the exchange and the subscriber equipments with radio lines. The solution is known as a wireless local loop (WLL) system.
The principle of the WLL system is shown in FIG. 1. A wireless stationary terminal equipment T comprises a radio unit 4 provided with an antenna, and a telephone adapter that connects a standard subscriber equipment 5 to the terminal equipment. The subscriber equipment may be a normal telephone set, a telefax terminal, or a modem. It is attached to the terminal equipment by inserting a standard plug in the adapter connection of the terminal equipment. The user utilizes the subscriber equipment 5 in the same way as in a conventional fixed network, even though the subscriber line connection consists of a radio line between the terminal equipment T and the base station BS 2 or 3. The base station may serve several subscriber equipments. The base station is connected to a special access network node 1, which in turn is connected to a standard exchange. Several base stations may be connected to one access network node 1.
The WLL system may be built by using components of an existing mobile phone system. The mobile system may be for example an analogous NMT system or a digital GSM system. In such a case, the signalling of the WLL system is in accordance with the system concerned, the base stations are standard base stations of this system, and the radio unit of the terminal equipment is similar to the radio unit of the mobile station or the terminal equipment may be a mobile station in a mobile system. An important component in the WLL system is the access network node that connects the subscribers to the standard local exchange. The access network node converts the WLL network signalling, for example NMT or GSM signalling, into signalling suitable for the fixed network (e.g. PSTN), and correspondingly it adapts the signalling of the fixed network to the WLL network interface.
The network node is connected to the local exchange with an open V2- or V5.1-type multiplexer interface that utilizes a 2 Mbit/s PCM system. If the local exchange only supports the two-wire interface, the network node is connected to the exchange by converting the V2 signalling into an analogous two-wire subscriber loop interface
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Mouly et al: "The GSM system for Mobile Communications", published by the Authors: 49, rue Louise Bruneau, F-91120 Plaiseau, France.
Goodman: "Second Generation Wireless Information Networks", IEEE Transactions On Vehicular Technology, vol. 40, No. 2, May 1991, p. 368-p. 369; p. 371-p. 373; figure 2.
Kuntz Curtis A.
Nokia Telecommunications Oy
Tieu Binh K.
LandOfFree
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