Multiplex communications – Duplex – Communication over free space
Patent
1997-04-01
1999-06-08
Vu, Huy D.
Multiplex communications
Duplex
Communication over free space
H04B 714
Patent
active
059109432
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method in a radio based telecommunication system, preferably the Digital European Cordless Telephone (DECT) system, in which a duplex channel is established utilizing repeaters which are performing the repeating without causing serious delays and/or interference.
2. Discussion of the Background
Repeaters in radio based communication systems can for many applications be of very great importance for the economy and functionality of the system. One example of a powerful repeater application is the radio based local network application OMA (Omradesbegransad Mobil Access=Area Restricted Mobile Access). The application implies that the terminating wire connection to the subscriber is replaced or completed by a surface covering radio. The subscriber is offered terminal mobility within one or more restricted areas. If repeaters are used the numbers of base units can be reduced by a factor of 10-100, resulting in the costs, for among other things the wire connection of base units, to be dramatically reduced. Consequently, repeaters will be very important in future systems.
The importance of repeaters has led to DECT-repeaters (Digital European Cordless Telephone) being presently standardized within ETSI (European Telecommunication Standards Institute) RES-3.
SUMMARY OF THE INVENTION
Compared with previous proposals within the field there is a need for refining and a need for further development to meet the demands which have lately arisen in connection with an ever increasing concentration on repeaters.
The present invention is based on the knowledge that, for avoiding serious delays, repeating must be performed within one time frame. The present invention solves certain technical problems which occur when repeating is performed within one time frame, such as: having access to all channels. repeaters and a base station is avoided without the need of separating repeating of the control signaling and useful data in different time frames. not "hearing the base station". DECT-specification.
THE SOLUTION
See the subsequent patent claims.
ADVANTAGES
The present invention achieves system technical advantages by a repeater function. Hand over will be possible between cells and repeaters. The system can be used in a radio system which uses TDMA/TDD/MC. Appropriate fields of application are radio based local networks, systems for wireless Private Automatic Branch Exchanges (PABX), and public access. In connection with the above mentioned applications, the CT-system DCT900 and DECT may be used in the short run. Notice that it may be quite possible to use one and the same DCT900 or DECT-portable (PP) in all of the above-mentioned applications.
Repeating is made within one time frame. One-way average delay which is added is therefore <2.5 ms. One does not need to use two duplex connections between a Radio Fixed Part (RFP) and a Repeater (REP) which results in less capacity demanding systems. In addition, Cyclical Redundancy Check (CRC) based macro diversity is possible. Macro diversity also becomes possible. The present invention implies that separation of repeating of control signaling and useful data is not needed, which simplifies encryption. Repeaters have a large economic and functional potential for the above-mentioned systems and for future systems using TDMA. The present invention also solves important problems with repeaters being used in a TDMA-system.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described below while, at the same time, is referred to by the enclosed drawings where:
FIG. 1 shows an example of the radio based network application OMA using repeaters,
FIG. 2 shows a method for establishing duplex channels,
FIG. 3 shows a flow chart for repeating in uplink, and
FIG. 4 shows a flow chart for repeating in downlink.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following abbreviations are used:
REP Repeater
PP Portable Part
RFP Radio Fixed Part (corresponding to base station)
ARK Access Right
REFERENCES:
patent: 5133080 (1992-07-01), Borras
Telia AB
Vu Huy D.
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