AU683496B2

AU683496B2 - Mobile telephone

Info

Publication number: AU683496B2
Application number: AU77530/94A
Authority: AU
Inventors: Vincenzo Langone
Original assignee: Alcatel NV
Current assignee: Alcatel Lucent NV
Priority date: 1993-11-12
Filing date: 1994-10-31
Publication date: 1997-11-13
Anticipated expiration: 2014-10-31
Also published as: AU7753094A; ITMI932415A1; IT1265178B1; ITMI932415A0

Description

P/0101O1 28/5/91 Regulation 3.2

AUSTRALIA

PatentsAct 1990 6 66.6 a. a 0 a 06 0 *009 6

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "MOBILE TELEPHONE" The following statement is a full description of this invention, including the best method of performing it known to us:too..: ot s 0

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This invention relates to a mobile telephone for communicating with a base station, of the type comprising an antenna, a radio section electrically connected with said antenna, and a low frequency circuitry, and to a base station for communication with the same.

The need of telephoning when aboard an aircraft, both when standing and when flying, is well known.

Basically, there are two possibilities to establish a connection between the aircraft and the ground telephone network: through intermediation of a satellite and through a series of ground stations provided with transceiver antennas pointing upwards and capable of tracking, through switching, the aircraft along its route.

Therefore, a transceiver connected with a telephone set will conceptually be found inside the aircraft.

The circulation of mobile telephones caused the problem of their use aboard aircrafts.

The solution proposed in the Future Public Land Mobile Telecommunication System (FPLMTS) provides for the installation aboard the aircraft of a base station called "mobile", similar to the "stationary" ground stations. Such mobile base station will then be connected to the ground 20 telephone network through a radio link. This solution is proposed for all the "vehicular" environments: ships, aircrafts, coaches, etc.

The use of such mobile telephones may cause radio interferences to the various radio equipment of the aircraft, the risk is higher as the number of apparatus used at the same time increases.

Even allocating in a suitable manner the radiofrequencies it is clearly necessary to limit the spurious emissions (harmonics) from the mobile telephone at the maximum extent.

It is an object of the present invention to provide a mobile telephone which does not cause radio interferences to the equipments of an aircraft and which does not cause problems as to allocation of frequencies, and to provide a corresponding base station capable of communicating with the same.

According to the invention, there is provided a mobile telephone for a mobile telecommunication system in a vehicular environment, said system

A

4 v comprising a plurality of such mobile telephones associated with a mobile base I IL Is station within said vehicular environment, said mobile base station being linked via a radio link with a fixed base station remote from said vehicular environment that is connected to a public telecommunications network, wherein said mobile telephone comprises a voice frequency circuit means, a radio frequency transceiver means operatively associated with an antenna means for providing a radio communication link with a remote fixed base station when said mobile telephone is operated outside said vehicular environment, and an optical transceiver means operationally associated with a light source means and a light detector means for providing an optical communication link between said mobile telephone and said mobile base station when said mobile telephone is operated within said vehicular environment, said mobile telephone further including controllable switch means for selectively coupling said voice frequency circuit means to either said radio frequency transceiver means or the said optical transceiver means.

15 The invention is based on the underlying idea that the connection **o between the mobile telephone and the mobile base station occurs through an optical link, in particular an infrared link. In this manner immunity from radio interference is practically assured and the frequency allocation problem is no a longer existent because of the enormous band available in the optical range.

20 Naturally, the mobile telephone must be capable of operating in conventional manner when outside the aircraft.

Thus it is advantageous that switching between radiocommunication and optical communication occurs automatically thanks to an optical signal irradiated inside the aircraft.

The same basic idea can be used also to solve the problem of mobile communications in private internal environments presented by FPLMTS system without care of frequency allocation and interferences; the same mobile telephone suitable for vehicular environments can be used also in such indoor environments.

In order that the invention may be readily carried into effect, an embodiment thereof will now be described in relation to the drawing showing a block diagram of the mobile telephone embodying the invention.

Such telephone set comprises an antenna A, a radio section RS electrically connected with the antenna A, a light source LS, a light detector LD, an optical section OS electrically connected with source LS and with detector LD, low frequency circuitry CKT having a signal input IS and a signal output US, and a power supply PS.

The radio section RS is comprised of a radio receiver RRX and a radio transmitter RTX connected together with antenna A, whilst the optical section OS is comprised of an optical receiver ORX and of an optical transmitter OTX respectively connected with the light detector LD and with the light source LS.

The signal input IS is connected through a first switch SW1 alternately with the radio receiver RRX and with the optical receiver ORX; the signal output US is connected through a second switch SW2 alternately with the radio transmitter RTX or with the optical transmitter OTX.

The outputs of the power supply PS are connected through a third switch SW3 and a fourth switch SW4 alternately with the radio section RS or with the 15: optical section OS in such a way that only one of the two sections is active at each time.

The receiver LD can be, a photodiode while the source LS can be an LED; more advantageously, these can operate in the infrared for the present application.

In general such detectors generate electrical signals proportional to the 0 intensity of the received light and such sources generate light whose intensity is 0000 proportional to the amplitude of the electrical signal provided at the input; as a result the optical section OS will be formed by a suitable electric circuitry.

Circuit CKT indicates the usual low frequency circuitry included in a conventional mobile telephone; for the present invention only the signal input IS and the signal output US have been shown.

The four switches SW1, SW2, SW3, SW4 are all controlled by a unique control signa' CNT and are designed to make the mobile telephone communicate alternately through radio signals or optical signals depending on the status of the control signal CNT. In the figure such switches are in an operating position such as to determine a radio communication.

Such control signal CNT may come from a switch located on the control panel of the mobile telephone to be manually operated or, more advantageously, it may depend on an electrical signal present at the output of a light detector not shown in the figure. Contrary to what is illustrated in the figure, it is possible to envisage the presence of either switches SW1 and SW2 only or of switches SW3 and SW4 only.

In the first circumstance, the outputs of the power supply PS shall be connected permanently with the radio section RS and with the optical section OS respectively; in the second circumstance the outputs of the radio receiver RRX and of the optical receiver ORX shall be connected together with the signal input IS and at the same time the signal output US shall be connected parallel with the inputs of the radio transmitter TTX and of the optical transmitter OTX.

The operation of the present radiomobile telephone will now be described.

When the telephone is in its normal operation, it will be in communication with a "stationary" base station and the switches shall be in a operating i"1: position such as to cause the communication to be a radio one, i.e. tr occur through the radio section RS and antenna A; when, on the contrary, the o telephone is in the coverage of an "indoor" base station, a "vehicular" mobile base station, it will be in communication with such "indoor" base station and the switches shall be in an operating position such as to cause the •X communication to be an optical one, to occur through the optical section OS, the detector LD and the source IS.

The change-over between these two different operating states may occur either manually, under care of the user, or automatically by means of the telephone itself.

In the second circumstance an optical signal capable of identifying the optical coverage area of the "Indoor" base station can be irradiated in the area of interest, eg., inside the aircraft; as soon as the mobile telephone receives such optical signal, it de-activates the radio communication and activates the optical communication, as soon as such optical signal is no longer received the inverse operation occurs.

Naturally, suitable steps are to be taken should such change-over occur during a telephone call: the simplest solution is the interruption of the call.

As to access techniques, transmission techniques and protocols, the simples solution is to adopt, as far as possible, the same solutions as used for radio communications also for optical communications.

In this way the circuitry additionally required by the mobile telephone of the present invention is restricted to means for transmitting and receiving optical signals.

In order for this mobile telephone to operate, it is necessary to prepare a suitable "indoor" base station.

Such a base station comprises an optical section for communritcating with a plurality of mobile telephones, a remote communication section for connection with a remote station, a low-frequency circuitry, electrically connected with the optical section and with the remote communication section, and control means capable of estab shing communications with mobile telephone and of routing them over such connection.

i3: In thp case of a mobile "vehicular" base station, the remote communication section is of radiofrequency communication type. When ,osm installed aboard an aircraft the effective reception and transmission of radio signals may occur, by using the radio equipment of the aircraft.

On the contrary, in case of a stationary "indoor" base station, the remote communication section is a line telephone interface connected with an exchange of th'; stationary telephone network through a single or multiple connection.

ii Naturally, the optical section will require at least one light detector and at •oooo least one light source.

S:ooi Given the limited coverage of such devices, it is advantageous in large :27: environments to provide two respective pluralities; for instance, inside an aircraft, a pair over each row of seats can be disposed, If envisaged, the optical signal capable of identifying the area can be irradiated from the "indoor" base station either through said plurality of light sources or by further means arranged for the purpose.

Claims

1. A mot lephone for a mobile telecommunication system in a vehicular environment, said system comprising a plurality of such mobile telephones associated with a mobile base station within said vehicular environment, said mobile base station being linked via a radio link with a fixed base station remote from said vehicular environment that is connected to a public telecommunications network, wherein said mobile telephone comprises a voice frequency circuit means, a radio frequency transceiver means operatively associated with an antenna means for providing a radio communication link with a remote fixed base station when said mobile telephone is operated outside said vehicular environment, and an optical transceiver means operatively associated with a light source means and a light detector means for providing an optical communication link between said mobile telephone and said mobile base station S. when said mobile telephone is operated within said vehicular environment, said mobile telephone further including controllable switch means for selectively coupling said voice frequency circuit means to either said radio frequency transceiver means or the said optical transceiver means.

2. A mobile telephone as claimed in claim 1, wherein said controllable switch means is a manually operated switch provided on said mobile telephone, 20 3, A mobile telephone as claimed in claim 1, wherein said controllable switch means couples said voice frequency circuit means to said optical transceiver means when an electric signal is produced at an output means of said light detector means, and couples said voice frequency circuit means to said radio frequency transceiver means when no signal is produced at said output means of said light detector means, 4, A mobile telephone as claimed in claim 1, wherein said controllable switch means couples said voice frequency circuit means to said optical transceiver means when an electric signal is produced at an output of a further light detector means provided on said telephone, and couples said voice frequency circuit means to said radio frequency transceijer means when no signal is produced at said output means of said further light detector means, A mobile telephone as claimed in claims 3 and 4, wherein said mobile base station includes means to irradiate said vehicular environment with light for ~~U4i, jdentifying optical coverage of said mobile base station for detection by said light detector means.

6. A mobile telephone as claimed in any one of the preceding claims, wherein said vehicular ,nvironment is the interior of an aircraft.

7. A mobile telephone substantially as herein described with reference to the figure of the accompanying drawing. DATED THIS NINETEENTH DAY OF AUGUST 1997 ALCATEL N.V. 0 0* 00 0 eo* II ~I 0, I ABSTRACT The invention relates to a mobile telephone suitable for use indoors, and to a base station for communication with the same. The basic idea consists in making the connection between the mobile telephone and a mobile base station occur through an optical link, in particular an infrared link. In this manner the immunity from radio interference is practically assured and the problem of frequency allocation is no longer existent due to the enormous band available in the optical range. *0 9 0e 9e eo I