Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1997-03-20
2001-01-16
Bost, Dwayne D. (Department: 2744)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S561000, C455S560000, C455S550100, C455S403000
Reexamination Certificate
active
06175747
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wireless local loop (WLL) system using a so-called “Personal Handy-phone System” (PHS), more particularly relates to a base transceiver station and a subscriber unit in a wireless local loop system and a method for operating the same.
Wireless local loop systems are currently being closely looked at among the various access type systems. They may be considered one of the optimal means for connecting a subscriber exchange (local exchange) with subscribers through radio channels.
One way for constructing such a wireless local loop system is to build upon the existing cellular networks used for cellular telephones.
Another way for constructing such a wireless local loop system is to build upon a new PHS network.
There are advantages and disadvantages to each of the above first and second techniques. The first technique is better from the viewpoint of the mobility of the subscriber (cellular telephone), that is, enables the cellular telephone to be used by a moving car, train, etc. On the other hand, the second technique is better from the viewpoint of the affinity and compatibility with existing public switched telephone networks (PSTN), that is, the cellular networks upon which the first technique is based exist as completely different systems from the public switched telephone networks, Further, the second technique is better from the viewpoint of the extremely high quality of the lines.
The present invention relates to a wireless local loop system established based on the second technique, that is, a wireless local loop system incorporating a PHS network.
2. Description of the Related Art
The basic technology for realizing the PHS type wireless local loop system upon which the present invention is founded already exists, as will be illustrated later, however, use of such a wireless local loop system by a large number of subscribers as part of a public switched telephone network in the broad sense of the term requires more than simple technical feasibility. It is further required that the wireless local loop system be practical.
Realization of such a practical wireless local loop system, however, requires that several tasks be solved. It is particularly important to solve the following six tasks:
1) Sharp reduction of the number of transmitting and receiving antennas which must be provided in the base transceiver station (BTS) so as to reduce the size and raise the efficiency of the base transceiver station. 2) Elimination of the problems inherent to conventional PHS networks, that is, the problem of the small service area per base transceiver system and the problem of the susceptibility to interference from other base transceiver stations.
3) Design of a configuration enabling full utilization of the inherent characteristic of a PHS network as mentioned above, that is, the excellent affinity and compatibility with a public switched telephone network.
4) Inexpensive realization of the functions of an integrated services digital network (ISDN) to eliminate the reliance of existing PHS networks on expensive ISDNs.
5) Minimalization of the deterioration in the quality of service to the subscriber due to the higher probability of the occurrence of faults in a base transceiver station accompanying the large number of cell stations (CS) required to be provided in the base transceiver station in the case of a cell with a large amount of traffic.
6) Relating to the task of 5), realization of a base transceiver station keeping the occurrence of the above faults to a minimum, having a high transmission quality, and having a high reliability.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a PHS type wireless local loop system, more particularly a base transceiver station and subscriber unit in such a wireless local loop system and a method of operation of the same which successfully solve several of the above six tasks, preferably which successfully solve all of the six tasks at the same time.
To achieve the above object, the present invention provides a base transceiver station constituted by a plurality of cell stations, each accommodating a plurality of subscriber units, a hybrid section integrally handling signals transmitted and received by the plurality of cell stations via a single antenna, and a multiplexing/demultiplexing unit integrally handling the signals transferred between the plurality of cell stations and an existing network. More particularly, the present invention provides a base transceiver station in a PHS type wireless local loop system which is small in size, can expand the service area without an increase of interference with other base transceiver stations, has a good affinity with existing networks, is provided with ISDN functions, and, at the same time, provides backup against faults, and improves the transmission quality and reliability.
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Hamada Yutaka
Ishikawa Hitoshi
Kubo Tsudoi
Mashima Rikihiko
Seta Mitsuru
Bost Dwayne D.
Fujitsu Limited
Helfgott & Karas P.C.
Persino Raymond B.
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