WO1997034433A1

WO1997034433A1 - A communication method and an adapter between a wireless telephone terminal and a data source

Info

Publication number: WO1997034433A1
Application number: PCT/EP1997/001288
Authority: WO
Inventors: Petrus Marinus Wilhelmus Teulings
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 1996-03-13
Filing date: 1997-03-12
Publication date: 1997-09-18
Also published as: AU2287797A

Abstract

A communication method and a communication adapter (45) serving as an interface device between a digital wireless telephone terminal (25) and an external digital data source (53). Communication data to be exchanged between the telephone terminal (25) and the data source (53) comprise signaling data and information data. Communication data (46) from the data source (53) are separated by means (49) into a signaling data output (47) and an information data output (52). The information data output (52) is converted by conversion means (50) into a data format and bit rate output (48) corresponding to the data format and bit rate of speech data to be exchanged by the telephone terminal (25). Return information data (48) from the telephone terminal (25) are converted by the conversion means (50) and combined by means (49) with signaling data (47) from the telephone terminal (25) to provide a single data output (46). In a preferred embodiment, the adapter supports the RS 232 interface protocol with the data source (53) and supports signaling (47) and information data (48) with the telephone terminal (25) in accordance with the DECT (Digital Enhanced European Telecommunications) standard. The adapter prevents making extensive software and hardware modifications in an existing wireless telephone terminal (25).

Description

A COMMUNICATION METHOD AND AN ADAPTER BETWEEN A WIRELESS TELEPHONE TERMINAL AND A DATA SOURCE.

Field of the Invention

The present invention relates generally to wireless telephone communication systems and more particularly to a method of and a communication adapter between a data source, such as a video terminal, and a wireless telephone terminal, such as a cordless telephone terminal.

Background of the Invention

Present wireless telecommunications systems provide efficient voice communication over channels having a limited transmission bandwidth. A typical example thereof is DECT (Digital Enhanced Cordless Telecommunications). DECT is a Multi-Carrier (MC) Tϊme Division Multiple Access (TDMA)/Time Division Duplex (TDD) format for radio communication between fixed or mobile remote units and fixed radio access units or base stations. Generally, one or more of the base stations connect to a so-called central interface unit or radio exchange which in turn connects to a Private Branch Exchange (PBX) or directly to an exchange of the Public Switched Telephone Network (PSTN).

With DECT ten radio carriers are available which, in the time domain, are each sub-divided into twenty-four 'time-slots'. Two such time-slots comprise one duplex communication channel, effectively resulting in twelve duplex communication channels per carrier. Each duplex communication channel serves a maximum information data bit rate of 32 kb/s. Through suitable coding techniques, this data rate is sufficient for providing POTS (Plain Old Telephone Service).

The twenty-four time-slots are transmitted in so-called TDMA-frames. A first halve of a frame comprises the so-called down-link transmissions, i.e. from the base stations to the remote units, and a second halve of a frame comprises the so- called up-link transmissions, i.e. from the remote units to the base stations. Further, each time slot typically contains synchronization data, control data, system data and information or user data.

For telephone communications, the user of a wireless telephone terminal makes use of the microphone and loudspeaker forming integral part of the terminal.

However, he or she may use a so-called headset device, comprising a microphone and an earpiece part external to the telephone terminal and replacing the build-in microphone and loudspeaker of the terminal.

The analogous speech information is processed as digitized speech samples, usually obtained by approximating the magnitude of an analogous sound sample to a nearest reference level. A technique which is know as quantization. In a process called Pulse Code Modulation (PCM) a digital code word comprising a number of data bits representing the particular reference level is generated. This digital representation is subjected to a further coding algorithm such as Adaptive

Differential Pulse Code Modulation (ADPCM). ADPCM is a coding technique in which the difference between two consecutive PCM values is quantized and encoded as an ADPCM data word. The quantization process is dynamically adapted to the momentary average signal level. With ADPCM, the PCM bit rate is further reduced to a lower ADPCM bit rate. An ADPCM algorithm widely used in personal or cordless telecommunications systems is described in CCITT Recommendation G.726.

In a DECT time slot, the information or user data field, also called B-field, comprises in case of speech communication eighty speech samples each coded as four bit wide ADPCM data words, also called nibbles. These speech samples are obtained during a frame cycle time of 10 ms, effectively resulting in 32 kb/s speech data per B-field. Arrangements of encoders for coding the speech samples and decoders for reconstructing the coded speech are known in the art as codecs.

For communication other than speech, some of the present telephone terminals are provided with an external data interface, e.g. a so-called RS 232 interface which is a widely known standard interface between data communication equipment and data processing terminal equipment. Through this interface, signaling data as well as information or user data is processed in serial form.

EP-A-0 618 746 discloses a radio telephone terminal having an RS 232 interface and comprising first means for processing speech data and second means for processing communication data other than speech data. Selection means are provided which select, by default, the means for speech exchange. The speech data and communication data are transmitted through separate, distinct wireless communication protocols.

EP-A-0 655 873 discloses an adapter for data transmission to and from a radio telephone which is particularly adapted for speech and data exchange.

That is, the data processing means of the radio telephone can be set in an operation mode in which data at an external bus can be transparently exchanged through the radio telephone, i.e. the digital signal processor (DSP) thereof. The adapter provides, among others, protocol and signaling translation, such that a data source operating in accordance with a first data communication standard can be connected to the radio telephone adapted for data transmission following a second, different data communication standard or protocol. Both, the information and signaling data between the adapter and the radio telephone are exchanged via a single external bus. The data exchange according to EP-A-0 618 746 and

EP-A-0 655 873 requires radio telephones which are particularly adapted for transmission of communication data or information data and speech data. Summary of the invention The present invention has for its object to provide a cost efficient solution permitting the exchange of communication or information data other than speech data to be processed through speech processing means forming an integral part of a wireless telephone communication terminal, i.e. a telephone communication terminal not particularly adapted for communication data processing. It is in particular an object of the present invention to provide a method of exchanging digital communication data between a digital source and a digital wireless telephone terminal, wherein such communication data comprise signaling data and information data.

It is another object of the invention to provide a method of exchanging such communication data through a wireless telecommunication system, in particular a system operating in accordance with the DECT standard. A yet another object of the present invention is to provide a communication adapter providing an interface between a digital data source, such as a video terminal, and a wireless telephone terminal, such as a cordless telephone terminal, in particular a telephone terminal operating in accordance with the DECT standard.

According to the present invention, there is provided a method of exchanging digital communication data between a digital data source and a digital wireless telephone terminal, which communication data comprise signaling data and information data other than speech data, the telephone terminal comprising speech processing means for the processing of speech data, signaling processing means for the processing of signaling data and communication processing means for the transmission of signaling data en speech data in accordance with a predetermined wireless communication protocol, wherein the signaling data and information data are separately processed by the telephone terminal.

For the transmission, by the telephone terminal, of communication data originated by the data source an embodiment of the method according to the invention comprises the steps of:

- converting the information data into a format corresponding to the format of data for processing by the speech processing means, and

- supplying the signaling data and converted information data to the communication processing means for transmission thereof in accordance with the predetermined wireless communication protocol.

For the transmission, to the data source, of communication data received by the telephone terminal an embodiment of the method according to the invention comprises the steps of:

- converting received data from the speech processing means into a format corresponding to the format of information data for processing by the data source, and - combining the signaling data and converted information data into communication data for transmission thereof to the data source.

Examples of data sources are video equipment connected to processing means operating with signaling or dialling software, such as Proshare™, automatic data processing equipment having means for automatically establishing data link connections, such as fax machines or Personal Computer

(PC) implemented data communication means. The method according to the present invention is based on the insight that, by converting the digital information data of the data source into the same format as the format of digital speech data processed by the speech processing means of the telephone terminal, essentially no adaptations in the data processing part of the telephone terminal are needed. This is to say, no expensive software of hardware modifications are required for the transmission of data from data sources not requiring speech processing by the telephone terminal.

In a preferred embodiment of the method according to the invention, in particular for use with a wireless telephone terminal operating in accordance with the DECT standard, wherein the speech processing means and the communication processing means are arranged for exchanging data in the form of nibbles, the information data of the data source are converted into nibbles for the transmission thereof by the telephone terminal and wherein nibbles received from the telephone terminal are converted into information data for transmission thereof to the data source.

In a further embodiment of the method according to the invention, additional data is exchanged between the data source, the telephone terminal and a telecommunication system to which the telephone terminal is linked, to switch of or bypass specific speech processing means including speech quantization means, speech coding/decoding means, echo cancellation means and muting means included in parts of the telecommunication system individual to the transmission link.

In a yet further embodiment of the method according to the invention, for automatic conversion of information data, the signaling data comprises data indicating the type of data to be exchanged, that is speech data and information data, such that the conversion is established subject to the type of data provided.

The conversion of information data of the data source may be provided by the telephone terminal itself, for example by a build in device such as processing device provided in the form of Subscriber Interface Module (SIM) card or by a communication adapter external to the telephone terminal.

The present invention provides also a communication adapter serving as an interface device between a wireless telephone terminal and an additional data source for the exchange of data other than speech data, and wherein digital communication data to be exchanged between the telephone terminal and the data source comprise signaling data and information data, and wherein the adapter comprises a first data port for connection to the data source and a data port for connection to the telephone terminal.

In accordance with the present invention, the data port for connection to the telephone terminal comprises a second data port and a third data port for the exchange of signaling data and information data, respectively.

The adapter, in an embodiment of the invention for the transmission by the telephone terminal of digital communication data originated from the data source, comprises: - data separation means, connecting to the first and second data port for separating the communication data at the first data port into signaling data at the second data port and information data, and

- data conversion means. operatively connecting to the data separation means and the third data port for converting the information data of the separation means into a data format at the third data port corresponding to the format of speech data to be exchanged by the telephone terminal.

In an embodiment of the adapter according to the invention for the transmission, to the data source, of communication data received by the telephone terminal, the adapter comprises: - data conversion means, operatively connecting to the third data port and data combination means, for converting information data at the third data port into a data format corresponding to the format of information data at the first data port, and wherein

- the data combination means operatively connect to the first and second data ports for combining the converted information data and signaling data at the second data port into communication data at the first data port. In the present description and the appended claims, the expression "communication data other than speech data" has to be construed as referring to data not requiring speech processing like speech signals exchanged via microphone and loudspeaker means forming part of the radio telephone.

Providing separate second and third data ports, i.e. separate processing of signaling and information data, relieves speed requirements set on the data link or bus for connection of the external data source and the telephone terminal. It will be appreciated that the above embodiments, in case of duplex links, may be combined into a single communications adapter. Providing such a separate adapter is a very cost efficient solution for those users who would like to expand the use of their present wireless telephone terminal for general data communication purposes.

In the preferred embodiments of the method and adapter according to the present invention the information data from the data source are converted into nibbles adapted to the data processing means of the telephone terminal in accordance with the DECT standard.

The invention provides also a wireless telephone terminal comprising an external data interface, having a first data port for signaling data and a second data port for information data, the first and second data port connecting to a central control unit of the telephone terminal for the processing of the data in accordance with a predetermined wireless communication protocol. This to transmit data other than speech processed through speech processing means forming part of the telephone terminal.

Following another embodiment of the invention, the above adapter may form part of the telephone terminal.

The present invention is in particular suitable for use with standard data communication protocol interfaces such as RS 232, providing a universal applicable data communication tool. It will be appreciated that the invention is neither limited to such interface protocol, nor its preferred use with the DECT radio transmission standard.

The above-mentioned and other features and advantageous of the invention are illustrated in the following description with reference to the enclosed drawings. Brief Description of the Drawings

Fig. 1 shows, in a schematic and illustrative manner, a cordless telecommunication system in which the present invention can be used.

Fig. 2 shows, in a schematic and illustrative manner, a digital data stream comprising data bursts.

Fig. 3 shows in detail the structure of a data burst of fig. 2.

Fig. 4 shows a simplified block diagram of an embodiment of a Central Interface Unit (CIU) used in the system of Fig. 1.

Fig. 5 shows a simplified block diagram of a radio communication unit taking the form of a telephone set for use with the present invention.

Fig. 6 shows a block diagram of an embodiment of a communication adapter according to the present invention.

Fig. 7 shows in a very schematic manner the operation of an information data conversion means for use in the communication adapter of Fig. 6, in particular for use with DECT.

Detailed Description of the Embodiments

Without the intention of a limitation, the invention will now be explained by its application in a cordless radio telephone system operating in accordance with the Digital Enhanced Cordless Telecommunications (DECT) standard.

Fig. 1 illustrates a typical DECT radio communication system, generally designated with reference numeral 1. The system comprises three essential elements: a Central Interface Uniζ(CIU) or radio exchange 2, a plurality of compact radio access units or base stations 3, which are installed throughout the area to be covered and connect directly to the CIU 2, and remote cordless or wireless radio communication units in the form of portable telephones or handsets 4 which connect over a radio link 9 to the radio access units 3.

Each radio access unit 3 provides service to a given area, called a cell, which is surrounded and/or overlapped by other cells of other radio access units 3, i.e. a so- called multi-ceil approach. The radius of indoor cells amounts typically from 10m - 100m, whereas the radius of outdoor cells typically ranges from 200m up to 5000m.

The CIU 2 is connected to a wired exchange 5 to which a plurality of wired telephones 6 can be connected. In business environments, this exchange 5 is generally a PBX (Private Branch Exchange) whereas in outdoor applications, such as Radio in the Local Loop (RLL) or Cordless Terminal Mobility (CTM), the exchange 5 is generally a Local Exchange (LE) which, like the PBX, is connected to a Public Switched Telephone Network (PSTN) 7, i.e. the ordinary wired public telephone network.

In RLL or CTM applications, the radio access units 3 may also connect over an air link 9 with so-called (Wireless) Fixed Access Units ((W)FAU) 8 which connect to a fixed telephone terminal or socket for the connection of a wired telephone 6. In CTM or RLL providing local mobility in the home, for example, the (W)FAU 8 is arranged to establish an air link with a handset 4 in the home (not shown).

In DECT, the information over the air link 9 is transmitted using a frame structure shown in Fig. 2. During the first halve of the frame, i.e. the first twelve time- slots designated R1, R2, ... R12, data from the radio access units 3 are received by the handsets 4 or (W)FAU 8, whereas in the second halve of each frame, i.e. the second twelve time-slots designated T1, T2, ... T12, the remote communication units 4 or 8 transmit data to the radio access units 3. A radio communication link between a radio access unit 3 and a remote communication unit 4 or 8 is assigned a slot in the first halve of the frame and a slot bearing the same number in the second halve of the frame. Each time-slot typically contains control data, system data and information or user data. In DECT, multiple time slots may be assigned to a particular radio link 9. A more detailed time-slot structure is shown in Fig. 3. The control data field contains a so-called synchronisation (SYNC) word, which has to be correctly identified at a radio access unit 3 or a remote communication unit 4 or 8 in order to process the received data. SYNC data will typically need 16 bits preceded by a preamble of 16 bits.

The system data field regularly contain system information on identity and access rights, services availability and, when required, information for handover to another communication channel in case of disturbances or transfer of a call to another radio access unit. Also paging, call set up and other signaling data are carried by the system data field, which is also called A-FIELD. System data will typically need 64 bits with a 16 bit Cyclic Redundancy Check word designated ACRC.

The information or user data, also called B-FIELD, comprise in case of a telephone call digitised speech samples obtained during the frame cycle time T_F of 10 ms. These speech samples are coded in accordance with the above-mentioned

ADPCM coding algorithm CCITT Rec. G.726 having a typical bit rate of 32 kb/s. This means that for each speech call 320 bits have to be transmitted and received during every frame. The ADPCM coded B-FIELD data contain 80 speech samples of 4 bit each. These ADPCM data are formed from the difference of successive 8 bit wide PCM coded speech samples.

The B-FIELD data is scrambled and a 4 bit Cyclic Redundancy Check word designated XCRC is formed from the information data. Including guard space, the total number of bits per time slot according to the DECT standard amounts to 480. These bits are transmitted at a system clock frequency or system bit rate of 1152 kb/s.

The selection of a radio channel is based on the so-called Dynamic Channel Allocation (DCA) technique, in which a free radio link or communication channel amongst a plurality of radio links or communication channels common to all radio access units 3 or cells of the system is selected. DCA requires no channel or frequency planning and the like, and optimises the occupation of the available communication capacity of the system. One of the basic features of the system is decentralised Continuous Dynamic Channel Selection (CDCS), a technique in which the handsets 4 or (W)FAU 8 selects the best available radio communication channel. With CDCS, channel selection is not limited to call set-up, but continues during the communication. CDCS optimises the radio link quality between a radio communication unit such as a handset 4 and a radio access unit 3 and the occupation of the available radio communication channels per cell. Reference is made to US Patents 4,628,152; 4,731,812 and a paper by D. Akerberg, "Novel Radio Access Principles Useful for the Third Generation Mobile Radio Systems", The Third IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, Boston Massachusetts, October 19-21, 1992.

DECT radio communication networks may comprise several DECT radio communication systems 1 , which can be independently operated by one or more operators, for example. Further, several DECT radio communication systems 1 may be operated independently in the same geographical area.

Fig. 2 shows a functional block diagram of an embodiment of the CIU 2, shown in Fig. 1. The CIU comprises a housing 10 containing a Central Processing Unit (CPU) 11, Speech Processing Units (SPU) 12, Cell Link Units (CLU) 13 and Line Termination Units (LTU) 14 and/or Digital Trunk Units (DTU) 15. The several units are connected to a digital system bus 19, and are powered by a Power Supply Unit (PSU) 16. Reference is made to Ericsson Technical Product Manual DCT 1800, EN/LZBNB 103 104 R3/1, by Ericsson Business Mobile Networks B.V.

The CPU 11 provides the overall control of the system and performs the tasks of system initialisation, call processing and intra-system mobility management. System testing and fault recovery and system statistics information are also provided by the CPU 11 , which information is available through an external interface 20.

The SPU's 12 form the communication data interface between the LTU's DTU's

14/15 and the CLU's 13. Each SPU 12 contains a number of speech processing circuits, which handle each the speech processing of one call. When a call is initiated, either by a handset 4 and (W)FAU 8 or an incoming call is received via an LTU 14 or DTU 15, a speech processing circuit is assigned to the call. T e main functions of an SPU are PCM to ADPCM transcoding and vice versa, dial tone generation and detection, and echo control.

The CLU's 13 provide the communication interface between the SPU's 12 and the corresponding radio access unit or base station 3. Each CLU 13 contains a number of link circuits, and each link circuit communicates with one base station 3. The main functions of an CLU are: transmitting up to twelve communication channels simultaneously from the CIU 2 to a radio access unit 3 over a data line 21 , and providing synchronisation and powering for the radio access unit 3. The base station control, TDMA-frame generation and radio link maintenance functions as described above, are implemented in the radio access unit 3. As indicated by reference numeral 22, the radio access units 3 may also be powered locally, via an AC/DC adapter.

The LTU's 14 provide an analogue interface between the PBX/LE 5 and the CPU 2. Each LTU 14 comprises a number of line termination circuits, each of which interfaces to the PBX through a 2-wire analogue subscriber line 17. Every analogue line 17 is dedicated to a specific handset 4 or (W)FAU 8 (Fig. 1), i.e. a specific telephone number. The main tasks of an LTU are to establish a physical connection between the PBX/LE and the CIU, on/of hook detection, ring signal detection, and analogue to digital speech processing (PCM) and vice versa.

The DTU 15 provides a digital interface between the PBX/LE 5 and the CIU 2. Every DTU 15 contains a number of digital trunk circuits. Each digital trunk circuit supports a Channel Associated Signalling (CAS) interface. In an embodiment, each CAS interface provides thirty fixed 64 kb/s digital communication channels, to which thirty subscribers are assigned; i.e. a 2 Mb/s data line. Dependent on the type of the PBX LE 5, a number of the functions of an LTU may also have to be performed by a DTU.

In a practical embodiment of the CIU 2 described above, up to 600 subscribers can be connected to one CIU 2. This means that the line connections between the CIU 2 and the PBX/LE 5 have to support up to 600 analogue 2-wire lines in case of LTU's 14, or a 40 Mb/s digital data link in case of DTU's 15. Fig. 5 shows a simplified block diagram of a wireless or cordless radio telephone terminal for use with the present invention. The radio telephone terminal 25 has four essential building blocks, i.e. a Central Control and application logic Unit (CCU) 26, a radio unit 27, a timing and Synchronisation Control Unit (SCU) 28 and a speech processing unit 29. The radio unit 27 comprises an air interface 30 having an antenna system coupled to a transceiver unit comprising a transmitter/modulator and a receiver/demodulator (not shown).

The SCU 28 receives data over the air interface 30 and the radio unit 27 from a radio access unit or base station 3 (Fig. 1), which data are processed in accordance with the system clock timing provided by the CIU or radio exchange 2 (Fig. 1). Signalling and synchronisation data information are removed from the received data by the SCU 28 and speech data are fed to the speech processing unit 29. The speech processing unit 29, among others, takes care of the deciphering of received data. A codec 31 decodes the received Digitised speech data into Analogue form (i.e. D/A conversion) for making it audible to a user of the handset via a loudspeaker 32 connected to the codec 31. Speech produced by the user is received by a microphone 33 and encoded into a suitable digital format by the codec 31, i.e A/D conversion.

This encoded speech data is fed to the speech processing unit 29 which, among others, takes care of encryption of the speech data. The SCU 28 adds suitable synchronisation and signalling information to the encrypted speech data. The radio unit 27 transmits this signalling and speech data via the air interface 30 for reception by a radio access unit 3 (Fig. 1) of the communication system to which the telephone set 25 is operatively connected.

The CCU 26 comprises a microprocessor or microcontroller and memory means, and operatively connects to the SCU 28. The CCU 26 essentially controls the system data and the communication with the user of the radio telephone set 25 via a keypad means 34, display means 38 and ring generator means 35, all operatively connecting to the CCU 26. Frame and time slot allocation and, in the case of a multi- earner multi-time-slot technology, also the various combinations of earner frequencies and time-slots are controlled by the CCU 26. In an embodiment of the telephone terminal 25 for operating under DECT, the SCU 28 and the CCU 26 are controlled by suitable software to process speech data taking the form of data bursts of eighty four-bit ADPCM data words or nibbles per time slot The codec 31 performs PCM/ADPCM transcoding of the digital speech data. Multiple time-slots may be assigned to a particular radio link.

The ring generator means 35 connect to a buzzer 36 for producing a ringing or alerting sound at the arrival of a call. Optionally a visual alerting signal may be emitted by a lamp or Light Emitting Diode (LED) 37, connected as shown. The display means 38, such as an LCD device, are operatively CCU 26 for displaying call information and other user and system data. For the overall powering of the telephone set 25 a battery and powering unit 39 is included.

Following the present invention, the telephone terminal 25 is provided with an interface 40 for external control and data processing purposes. The interface 40 comprises a first data port 41 operatively connecting to the CCU 26 for the exchange of signalling data, and a second data port 42 operatively connecting to the SCU 28 for the exchange of information data. Note that the interface 40 may be designed as one single plug or socket type connector, including both data ports. The CCU is arranged such that signalling data provided at the first data port 41 is handled in accordance with the communication protocol (e.g. DECT) and essentially comparable to signalling data provided by the user of the telephone terminal. Information data exchanged at the second data port 42 is processed by SCU in essentially the same manner as speech data exchanged with the speech processing unit 29 according to the predetermined communication protocol. That is, in DECT the data is transmitted as eighty nibbles in the B-field of a time slot.

Although the communication unit 25 has been showed in the form of a portable wireless telephone set 4 (Fig. 1), part thereof i.e. essentially designated by the reference numerals 26-31, 39 and 40 may form a (W)FAU 8 (Fig. 1).

Fig. 6 shows a block diagram of a preferred embodiment of a communication adapter 45 according to the present invention. The adapter shown is of the type for duplex communication and comprises a first data port 46, a second data port 47 and a third data port 48. A data separation/combination means 49 connects to the first data port 46. From the data separation/combination means 49 a first line 51 connects to the second data port 47 and a second line 52 connects to data conversion means 50, which in turn connect to the second data port 48. For clarity purposes/the adapter 45 is shown connected to a data source 53 and a telephone terminal 25.

The first data port 46 serves as an interface port to the data source 53, such as a video or data processing equipment etc., exchanging communication data comprising information data and signaling data. This first data port 46 may support any known interface protocol. In a preferred embodiment of the adapter 45 the first data port 46 supports an RS 232 protocol, which is a known standard interface between data communication equipment and data processing equipment.

The second data port 47 provides a signalling interface port to the telephone terminal 25, or in general a communications terminal. This second data port 47 may support any known or proprietary signaling protocol. In the preferred embodiment of the adapter 45, the second data port 47 supports also an RS 232 protocol, however less complex than the first data port 46.

The third data port 48 constitutes an information or user data port to the telephone terminal 25, or in general a communications terminal. This third data port 48 may serve any data format used by the telephone terminal 25 for the exchange of speech data. The third data port 48 may be either a serial or a parallel port. In the preferred embodiment of the adapter, the third data port 48 exchanges information data in the form of eighty nibbles with a cycle time of 10 msec. This in accordance with the DECT standard. Data rate and format conversion are provided by the conversion means 50. The adapter 45 operates as follows.

Communication data received at the first data port 46 are separated by the separation/combination means 49 into signaling data and information data.

Received signaling data are interpreted by the separation/combination means 49 or any other interpretation means (not shown), and such signaling data required by the telephone terminal 25 to set up a call etc. are submitted at the second data port 47. Information data are converted by the conversion means 50 into a data rate and data format corresponding to the telephone terminal processing means, and outputted at the third data port 48.

Signaling data from the telephone terminal 25 and received by the adapter 45 at the second data port 47 are again interpreted by the separation/combination means 49 or any other separate interpretation means (not shown) and transmitted to the data source 53. These data are, however, by the data separation/- combination means 49 combined with information data received from the telephone terminal 25 after conversion by the conversion means 50.

As already mentioned in connection with Fig. 4 above, the CIU or radio exchange 2, and in some embodiments also the access units or base stations 3, compπse speech processing means, such as the SPU 11, providing PCM to ADPCM transcoding, muting control, dial tone generation and detection, and echo control. Muting algonthms operate on the speech data at the B-field, in order to reconstruct speech in case of lost data (frames). For communication data other than speech data, in order to provide a transparent data link through a communication system, the speech related operations such as PCM/ADPCM transcoding, muting control etc. have to be switched off or bypassed.

In order to establish a transparent data link at those parts of the system individual to particular transmission link, additional signalling data are provided by the adapter 46, i.e. the separation combination means 49. In a preferred embodiment of the invention, this additional dialling information compnses either one or a combination of the speαal Dual Tone Multi-Frequency (DTMF) signalling characters "*" or "#". For example "# #" as an extension of the dial stnng. The access units 3 and the CPU 11 of the CIU 10 will, on receipt of this extra dialling information, switch off or bypass the relevant speech processing means.

Those skilled in the art will appreαate that for simplex operations, the communication adapter 45 may be tailored to exchange communication data from the telephone terminal 25 only, or to exchange communication data from the data source 53 only. Further, the communication adapter 45 and the telephone terminal 25 may be arranged such that when the adapter is connected to the telephone terminal, the signalling means and speech communication means of the telephone terminal are automatically disabled automatically disabled or switched into the operation mode for exchanging communication data with an external data source

Fig. 7 illustrates, in a very schematic manner, the operation oi the data, conversion means 50 of the adapter 45 for use with DECT. Information data to be exchanged via the first data port 46 is in serial form retrieved in a shift register 55. Data received via the line 52 (Fig. 6) is, under control of DECT synchronisation control means 57, read from the shift register 55 as eighty nibbles 56 for further processing by a telephone terminal via the third data port 48. Nibbles 56 received from the telephone terminal are written in the shift register 55 for output to the data source, i.e. the first data port 46 via the line 52.

In a practical embodiment of the invention, the communication adapter 45 comprises separation/combination means 49 consisti^'ng of a Mitsubishi 37702 16-bit microcontroller, 8 kbyte RAM means and 256 kbyte FLASH memory. The several data ports 46, 47 and 48 comprise appropriate data drivers for exchange of the data bits. In an embodiment, a 38.4 kb/s communication data bit stream at the first data port 46 in an RS 232 format is transformed into an 28.8 kb/s information data stream at the line 52 and exchanged as a 32 kb/s information data stream at the third output port 48. However, other data rates and even multiples of 32 kb/s may be handled by the telephone terminal in allocating multiple time slots to this terminal.

The adapter may be incorporated in a telephone terminal in the form of a build-in processing device, such as Subscriber Interface Module (SIM) card for example

Although the present invention has been described with reference to a DECT communication system, it will be understood that the novel data communicatjon method and aαapter according to the present invention can be used more generally in digital wireless telephone systems having packet sound or voice transmission/reception, and in particular with communication systems exchanging digidsed data, such as the digital cordless CT2 system and the digital mobile cellular systems.

Claims

1. A method of exchanging digital communication data between a digital data source and a digital wireless telephone terminal, said communication data comprising signaling data and information data other than speech data, said telephone terminal comprising speech processing means for the processing of speech data, signaling processing means for the processing of signaling data and communication processing means for the transmission of signaling data and speech data in accordance with a predetermined wireless communication protocol, wherein said signaling data and information data are separately processed by said telephone terminal, characterized by the steps of:

- converting said information data into a format corresponding to the format of data for processing by said speech processing means, and

- supplying said signaling data and converted information data to said communication processing means for transmission thereof in accordance with said predetermined wireless communication protocol.

2. A method of exchanging digital communication data between a digital data source and a digital wireless telephone terminal, said communication data comprising signaling data and information data other than speech data, said telephone terminal comprising speech processing means for the processing of speech data, signaling processing means for the processing of signaling data and communication processing means for the reception of signaling data and speech data transmitted in accordance with a predetermined wireless communication protocol, wherein signaling data and information data are separately processed by said telephone terminal, characterized by the step of:

- converting received data from said speech processing means into a format corresponding to the format of information data for processing by said data source, and

- combining said signaling data and converted information data into communication data for transmission thereof to said data source.

3. A method according to claim 1 or 2, wherein said speech processing means and said communication processing means are arranged for exchanging data in the form of nibbles, wherein said information data of said data source are converted into nibbles for the transmission thereof by said telephone terminal and wherein nibbles received from said telephone terminal are converted into information data for transmission thereof to said data source.

4. A method according to claim 1 , 2 or 3, wherein said wireless communication protocol is based on DECT (Digital Enhanced Cordless Telecommunications) and said communication data with said data source is exchanged based on an RS 232 interface protocol.

5. A method according to any of the previous claims, wherein said digital wireless telephone terminal is arranged to set up a transmission link in a wireless telephone communication system, such that said transmission link is individual to said wireless telephone terminal and said telecommunication system, wherein additional signaling data is exchanged between said data source, said telephone terminal and said telecommunication system to switch of or bypass specific speech processing means including speech quantization means, speech coding/decoding. means, echo cancellation means and muting means included in parts of said telecommunication system individual to said transmission link.

6. A method according to claim 5, wherein said additional signaling data comprise one or a combination of special signaling characters "#" and/or "*".

7. A method according to any of the previous claims, wherein said signaling data comprise data indicating the type of data to be exchanged, that is speech data and information data, and wherein said conversion of data is established subject to said type of data provided.

8. A method according to any of the previous claims, wherein said conversion of said information data of said data source is provided by said telephone terminal.

9. A method according to any of the claims 1-7, wherein said conversion of said communication data of said data source is provided by a communication adapter external to said telephone terminal.

10. A communication adapter providing an interface between a digital wireless telephone terminal and a digital data source for the exchange of data other than speech data, wherein digital communication data to be exchanged between said telephone terminal and said data source comprise signaling data and information data, said adapter comprises a first data port for connection to said data source and a data port for connection to said telephone terminal, characterized in that - said data port for connection to said telephone terminal comprises a second data port and a third data port; said adapter further comprises:

- data separation means, connecting to said first and second data ports for separating said communication data at said first data port into signaling data at said second data port and information data, and - data conversion means, operatively connecting to said data separation means and said third data port for converting said information data of said separation means into a data format at said third data port corresponding to the format of speech data to be exchanged by said telephone terminal.

11. A communication adapter providing an interface between a digital wireless telephone terminal and a digital data source for the exchange of data other than speech data, wherein digital communication data to be exchanged between said telephone terrhinal and said data source comprise signaling data and information data, said adapter comprises a first data port for connection to said data source and a data port for connection to said telephone terminal, characterized in that:

- said data port for connection to said telephone terminal comprises a second data port and a third data port; said adapter further comprises:

- data conversion means, operatively connecting to said third data port and data combination means, for converting information data at said third data port into a data format corresponding to the format of information data at said first data port, and

- said data combination means operatively connecting to said first and second data ports for combining said converted information data and signaling data at said second data port into communication data at said first data port.

12. An adapter according to claim 10 or 11 , wherein said conversion means are arranged to exchange information data at said third data port in the form of nibbles.

13. An adapter according to claim 12, further comprising synchronization means operatively connecting to said conversion means for exchanging synchronization data at said third data port, in particular synchronization data in accordance with a communication protocol based on DECT (Digital Enhanced Cordless Telecommunications).

14. An adapter according to any of the claims 10 to 13, wherein said first and second data ports are arranged for serial bit transfer, in particular based on an RS 232 protocol.

15. An adapter according to any of the claims 10 to 14, wherein said data separation means are arranged to provide at said second data port additional signaling information to switch of or bypass specific speech processing means including speech quantization means, speech coding/decoding means, echo cancellation means and muting means included in parts of a telecommunication system providing a transmission link individual to a digital wireless telephone terminal to which said communication adapter, in use, is connected.

16. A wireless telephone terminal having an external data interface, characterized in that said data interface comprises a first data port for signaling data and a second data port for information data other than speech data, said first data port operatively connects to a central control unit of said telephone terminal for the processing of signaling data in accordance with a predetermined wireless communication protocol and said second data port operatively connects to a timing and synchronization control unit of said telephone terminal for processing of information data corresponding to a speech data to be exchanged by said telephone terminal in accordance with a predetermined wireless communication protocol.

17. A wireless telephone terminal according to claim 16, comprising an adapter according to any of the claims 10 to 15.

18. A wireless telephone system, comprising a plurality of geographically spread radio access units, such as base stations for establishing communication links with a plurality of geographically spread remote wireless communication units, such as wireless telephones, said radio access units having access to a private and/or public telecommunication network through a central interface unit, such as a radio exchange, characterized in that said central interface unit and/or said radio access units are provided with means for the detection of additional signaling information, and means for switching of or bypassing specific speech processing means, among which speech quantization means, speech coding/decoding means, echo cancellation means and muting means subject to said additional signaling information.