The invention relates to a method and system for transferring voice or data through one channel between two devices as described in the pre-characterizing parts of claims 1 and 12 respectively.

A method and system of such type are disclosed by WO-A-9949608.

This document discloses the use of multiple analogue plain old telephone services (POTS) signals providing multiple plain old telephone type services on a single telephone line. In particular, at each of several premises a plurality of telephone or voice devices and data devices can be connected to a premises line, which, like other premises lines from other premises, is connected to a central POTS-switch. Voice (signals) is transferred during concatenated voice time slots. If a data device wants to transfer data over a premises line to which it is connected it monitors the premises line for the occurrence of a silent voice slot. The data device may determine the occurrence of a silent voice slot by detecting itself whether some time at the beginning of a voice slot is silent or the data device can be informed about a next voice slot being silent by another device which was transferring over the same premises line.

With said prior art method and system the transfer of voice prevails. Therefore data will be transferred only occasionally and it may take quite some time before a block of data has been transferred. Further, since the occurrence of silence must be detected by discriminating between voice signals and noise, the occurrence of silence may depend on the quality of a channel, which is a voice channel, between devices of the communication system, and of environment sounds at the location of the voice device. This will hamper the transfer of data even more. Therefore the prior art method and system are not suitable to be used to transfer data relating to emergency situations and real-time access without delay.

It is an object of the invention to improve the prior art method and system such that it will be possible to transfer data without delay using the full bandwidth of the channel, or providing a lower

minimum transfer rate and allowing data transfer using just part of the bandwidth in frequency domain, in time domain or in both domains, including during periods of silence of voice transfer.

Said object is obtained according to the invention by the method and system as described in claims 1 and 12 respectively.

According to the invention the transfer of voice does not have priority under all circumstances but may be subordinate to a priority of a data transfer demand.

According to preferred embodiments, as described in dependent claims, data transfer can be carried out with or without concurrent transfer of voice dependent on a degree or an order of priority of the data transfer demand. Concurrent transferring of data and voice can be carried out in several ways while maintaining some minimum data transfer rate.

The invention will be described in further detail below with reference to the drawings, in which: fig. 1 shows a first simple communication system for illustrating the invention ; fig. 2 shows a flowchart of an operation of the system shown in fig. 1 according to a first set of priorities; fig. 3 shows a flowchart of an operation of the system shown in fig. 1 according to a second set of priorities; fig. 4 shows a flowchart of an operation of the system shown in fig. 1 according to a third set of priorities; fig. 5 shows a second simple communication system for illustrating the invention ; and fig. 6 shows a replacement part of the flowcharts shown in figs.

2,3 and 4 for illustrating possible operations of the system shown in fig. 5.

Fig. 1 shows a simple communication system comprising two devices 1,2. The devices 1, 2 can be of any type between which a communication link through a voice channel can be established, i. e. through a wired connection or through a wireless connection. In particular said link is a time division multiple access (TDMA) link, and more particular the link is a Digital Enhanced Cordless Telecommunication (DECT) link. In the latter case the devices 1 and 2 are a base station 1 and a portable terminal 2 respectively. This will be taken as an example hereinafter.

With a DECT communication system there are twelve channels available for traffic from base station 1 and twelve channels for traffic towards base station 1. Therefore, a link between base station 1 and terminal 2 comprises two channels 3,4.

Although not shown base station 1 can be connected to any further communication devices through any type of communication network. Terminal 2 can be provided with a microphone for receiving sound from a user and a loudspeaker or the like for generating sound from voice signals received from base station 1. However, the invention is not limited to this, and voice signals can be input and/or output also by different ways, in particular by wire. In addition, terminal 2 is suitable to input and output data in any possible way, by wire or wireless, to and from base station 1 respectively.

According to a first embodiment the system shown in fig. 1 can operate as will be explained with reference to fig. 2.

Firstly, for transferring voice and/or data, a communication link must be established between base station 1 and terminal 2.

Having such communication link (decision block 22) it is checked, or monitored on an event interrupt basis, if there is data present to be transferred (decision block 23). If there is no data present to be transferred from the device of concern (base station 1 or terminal 2) the channel 3,4 from said device 1,2 will be fully available for transfer of voice (block 24). If there is data to be transferred a priority of the data transfer demand is detected (block 25). Then, the data will be transferred to the other device dependent on the priority as determined.

If a highest degree or order of priority is detected (decision block 26) the use of the channel towards the other device is switched, if not yet done, from a voice transfer mode to a data transfer mode (block 27). Thus, this priority means the taking over of the channel by data. If no such priority was determined data can still be transferred during periods of silence in voice. Therefore the occurrence of silences in voice is detected (block 28). Upon detection of such silence (decision block 29) the channel will be used for transferring data (block 27), but only for the duration of the detected silence. If no silence is detected the transfer of voice will be continued (block 24).

The diagram shown in fig. 3 differs from the diagram shown in fig. 2 by the addition of a further priority dependent decision (decision block 31). That is, if no priority for complete taking over the channel for transfer of data was determined (decision block 26), but a priority for sharing the bandwidth of the channel (decision block 31) said bandwidth is shared between voice transfer and data transfer (block 32). In the diagram block 32 leads to block 27 only, but it will be clear that with such shared bandwidth there will be transfer of voice (block 24) concurrently as well.

The diagram shown in fig. 4 differs from the diagram shown in fig. 3 by that a further priority dependent decision is made. That is, if the determined priority is not for taking over the channel completely for transfer of data, it is checked whether the determined priority demands for transferring of data on a timed basis (decision block 41). At the occurrence of said timed data transfer priority the data as present will be enabled to be transferred in timed bursts of one or more time slots (block 42). At the occurrence of such time slot, which enables data transfer, the data can be transferred during silences in voice, as described with reference to fig. 2, or the data can be transferred with the employment of shared bandwidth of the channel as described with reference to fig. 3. At other times then said time slots voice is transferred instead of data. Although not shown in detail in fig. 3, the duration of an interval between said bursts, the number of time slots within such bursts and the duration of time slots can be varied dependent on demands or circumstances.

While with the operation with shared bandwidth (block 32 of fig.

3) the transfer of voice will not be interrupted its quality will decrease with respect to a situation without transfer of data, in particular without said sharing of bandwidth. On the other hand, with the operation with timed date transfer, as described in particular with reference to block 42 of fig. 4, the transfer of voice will be interrupted at times but not at other times where its quality will be maintained at maximum.

The system shown in fig. 5 comprises the base station of fig. 1, a voice terminal 51 and a data terminal 52. Between the base station 1 and the voice terminal 51 a first link can be established and between the base station 1 and the data terminal 52 a second link

can be established. Both links use the same channels 3,4 for traffic from and towards the base station 1 with respect to both terminals 51,52. Therefore only one link will be made active at a time for transferring voice or data. This is illustrated by fig. 6, which shows two branches only of a flowchart comprising blocks 24 and 27 shown in figs. 2,3 and 4 respectively. As shown by blocks 61 and 62 the use of the channel 3,4 of concern is switched, if not yet done, for transferring voice between base station 1 and voice terminal 51 and for transferring data between base station 1 and data terminal 52 respectively.

From the above it will be clear that an operation as described with reference to figs. 2,3, 4 and 6 can be carried out by either device, i. e. base station 1 and terminal 2 and 51, or concurrently by both devices. Therefore, the system can operate as if it was a half-duplex system, e. g. transferring voice in one direction and transferring data in the other direction between two devices.

Although the invention is described for the transfer of data from a device in which detection is made for a data transfer demand and a communication condition (such as silence), such detection and the determination of a priority of data transfer can be distributed among the devices, irrespective from which device data is to be transferred. The only requirement is that appropriate signalling of such detection and/or determination of priority can be made between the devices. Usually, such as with a wired network and with DECT, this will be possible.

The described operations according to the method and system according to the invention can be realised in different ways, that is by software or hardware or a combination thereof. For the hardware implementation first detection means can be used for detecting a demand for transferring data, second detection means for detecting a communication condition, and control means for allowing controlling data transfer instead of voice transfer through the channel dependent on what has been detected and the priority which has been determined. A person skilled in the art will have no problem with understanding this and therefore such means have not been shown as such.