Digital telecommunications device

The present invention relates to a device according to the Preamble of claim 1, ie a digital telecommunication device with one or more cordless Mobile parts, said mobile parts and the base station, with can of this stand or contact, in the Are able to change the transmission / reception frequency repeated.

Such telecommunication device, for example, an operating according to the DECT standard radio system.

The basic construction of such a radio system is shown in Figure 1 illustrates.

The system shown in the Figure 1 consists of a base station B and a plurality of cordless telecommunications terminal equipment TE1 to TEn. The cordless telecommunications terminal equipment TE1 to TEn are the example under consideration Mobile phones, which are able, by radio with the base station B communicate.

Instead of cordless telecommunications terminal equipment TE1 to TEn or in addition to these, also cordless Connection socket for connecting corded telecommunications terminal equipment are used. cordless Telecommunications terminal equipment, the cordless connection boxes and similar institutions are already initially mentioned handsets.

The data transmission between the base station B and the Handsets in units of so-called frames, more specifically TDMA frames, TDMA for Time Division Multiple Access is available and states that the frames constructed so are that the base station in consecutive time slots (So-called timeslots or slots) of each Frame sequentially logged-with all her can communicate handsets, and this then respectively under Utilization of the full bandwidth of the transmission channel. The TDMA method is well known and needs no further Explanation. The basic structure of the implementation the TDMA method suitable (TDMA) frames is explained with reference to FIG. 2

As can be seen from the Figure 2, is such Frame, more specifically, the consideration here DECT full-slot frame from 24 identical long time slots or slots (full slots) together. The first 12 of the 24 slots are from the transmitted base station to the mobile units, and which adjoining second 12 slots are of the handsets transmitted to the base station. Specifically, the zeroth slot of every frame from the base station to a zeroth handset, the first slot from the base station to a first handset, the second slot from the base station to a second handset, ..., the eleventh slot of the Base station to an eleventh handset, and vice versa the twelfth slot from zero handset to the base station, the thirteenth slot from the first handset to the base station, the fourteenth slot from the second handset to the base station, ... and the twenty-third slot from the eleventh to the handset transmitted base station.

A frame or the 24 slots of a frame are within transmitted 10 ms. Each slot comprises 480 bits in around 417 transmitted microseconds (in 416.66 microseconds). As indicated in the figure 3 is, the 480 bits are distributed on a 32-bit-wide Sync field, a 388-bit-wide D-box, a 4-bit-wide Z-field, and a 56-bit-wide guard-space field.

To transfer the actually interesting payload (For example, voice data) are 320 bits in the D field reserved. The base station can therefore within 10 ms 320 bits comprehensive user data to each of the handsets ship and the same amount of user data from each of the Handsets received; the transmission rate of user data between the base station and each of the handsets is thus 32 kbit / s in each direction.

As with any data transmission errors can occur here. This is particularly the case when the transmission / reception frequency is superimposed by disorders.

Among other things, therefore, are in accordance with the DECT standard working Radio systems a total of 10 different frequencies as transmitting / receiving frequencies. The selection of each as a transmission / reception frequency to be used frequency carried out by the respective handsets considering the local transmission and reception conditions.

Although characterized each handset independently of the other Handsets over a selected frequency even with the base station can communicate, error or the respective Transmission / reception frequency but not completely excluded. This is especially the case when it comes to be recurrent brief interference concerns.

The present invention is therefore based on the object, the telecommunication device according to the preamble of Claim 1 such that disturbances on the transmission / reception frequency based on transmission errors easily reducible to a minimum.

This object is achieved according to the in characterizing Part of claim 1 features claimed dissolved.

Accordingly, it is provided that the mobile parts and / or the Base station are adapted to disturbed transmit / receive frequencies a predetermined time after the detection of the Interference from the use excluded.

This also allows the use of such frequencies as Transmission / reception frequency can be prevented that only occasionally are momentarily disturbed; Transmission errors on interference the transmitting / receiving frequency is based, are therefore very easily reducible.

Moreover, characterized the selection of the respective Transmission / reception frequency can be facilitated, for as the disturbed or probably disturbed frequencies of use as transmission / reception frequency are excluded, it can at least when the unperturbed frequencies in short Intervals cyclically used as a transmission / reception frequency will be risking any of the unlocked Frequencies without prior examination as transmission / reception frequency to use.

Advantageous developments of the invention are of the subclaims.

The invention is described using an exemplary embodiment explained in more detail with reference to the drawing. Show it<dl tsize="8"><dt>figure 1</dt><dd>the construction of an operating according to the DECT standard Radio system, and</dd><dt>figure 2</dt><dd>the format of the data transmitted between a base station and with these communicating telecommunications terminal equipment one operating according to the DECT standard Radio system to be replaced.</dd></dl>

The telecommunication device described below near as an operating according to the DECT standard System digital telecommunication device with a or more cordless handsets; it is, however, to Use in the so-called 2.4 GHz ISM band designed which extending from 2400 to 2483.5 MHz and by the FCC (Federal Communication Commision US) under certain Requirements for the operation of such telecommunications equipment was released.

It was already pointed out at this juncture that the Telecommunications device according to the invention not only to Using the 2.4 GHz ISM band is suitable, but in principle also in any other frequency bands for use can come.

The communication between the handsets and the base station may as in the system described at the outset via a plurality of time slots or TDMA frames comprising slots carried out; the TDMA frames may also turn a having length of 10 ms. The structure and the length However, the frames are not limited to; they are also any other securable.

The transfer rate with which the individual bits of the transmitting information to be transmitted, is under consideration Example relative to the bit rate of the above Telecommunication device described halved, thereby the per unit time transferable or exchangeable dataset reduced accordingly. The invention is, however, not only in telecommunications equipment with this Bit transfer rate applicable, but can in principle even when any other bit transmission used come.

The transmit / receive frequencies, using which the transmitted information to be transmitted, only changed once per frame. The selected transmission / reception frequency is used for communication between Base station and all connected handsets used; it can no longer define each handset individually, over which frequency communication with the base station is to take place.

There are at least 75, in the example considered even 90 Frequencies available, the same frequency as in the Middle Transmission / reception frequency may be used.

Which of these frequencies in each case as the next transmission / reception frequency is used, more specifically the sequence in wherein the available frequencies as a transmission / reception frequency are to be used, is in a pseudo-random frequency list set, both in the base station is also available in the handsets.

The pseudo-random frequency list is from the base station and the handsets synchronized through sequentially. That is, simultaneously at the (in the base station and the handsets occurring) frequency change is in each case that frequency used as the new transmitting / receiving frequency determined by the represents the next entry in the pseudo-random frequency list becomes. The frequency changes are not deteriorated by Transmission / reception conditions triggered but made irrespective of frame by frame at predetermined times.

Should you jumped frequency be disturbed, so changes thereby the operation, at least initially nothing; the handsets and the base station meet due to the synchronous traversal identical content Pseudo-random frequency lists after a certain time (in the next or a later frame) automatically when next (according to the frequency list) undisturbed frequency again.

The base station and the handsets are the example under consideration designed so that it can detect when the received data due to the use of a disturbed Transmission / reception frequency were transmitted incorrectly or could be. In this case, from the base station or the handsets concerned the errors obtained last User data (for example, voice data) output. On this way, even disturbances over three consecutive Frames extending without perceptible loss bridged.

Prolonged interference can be avoided if the Pseudo-random frequency list is applied so that between successively to be used as a transmission / reception frequency Frequencies, a large frequency spacing is. Thereby reducing the risk of typical wide-band interferer such as microwave ovens, a longer (several consecutive Frames) cause lasting disruption.

Additionally or alternatively, those frequencies at which error-free communication is not possible in subsequently treated separately. Whether an error-free communication is possible or not, can be either in the base station controlled or in the handsets, or both will. The detection can, for example (but not exclusively) carried out by a CRC checksum check. The disturbed frequencies are collected in a list. This list is in the example considered in the base station out. Although the list additionally or alternatively can be performed in the handsets, it is for reasons of cost preferable that the list only in the base station to be led. The base station can simultaneously namely with be connected multiple handsets, and there are under consideration For indeed all handsets respectively over the same frequency with the base station communicate. Is in the base station or in one of the handsets an error the transmission / reception frequency registered, it is of the relevant Means the next error-free connection a corresponding message to the list of faulty Frequencies leading (s) point (s) received.

Conversely from the spot said list leading, in the example under consideration, therefore, from the base station at regular Intervals (for example, in each information field the burst transmission) to the respective other radio parts information transmitted, the next as a transmission / reception frequency represent usable or not usable frequencies or make up the next as a transmission / reception frequency identify usable or not usable frequencies leave. Characterized know both the base station and the handsets each the next (for example, K) as a transmission / reception frequency to be used frequencies. Among the frequencies used or to be used are the not previously included as disturbed classified frequencies. It So only such frequencies as transmit / receive frequencies are used, which under the circumstances given do not indicate any faults; the base station and the Handsets skip classified as disturbed frequencies in the pseudo-random frequency list.

If a hitherto faultless rated frequency due changed circumstances suddenly disturbed, so goes the connection between the base station and one or more of Handsets only briefly lost, for both the base station and the handsets still know so the next K-1 Frequencies thereafter as transmission / reception frequency are to be used, so that the base station and the Handsets undisturbed sooner or automatically contact each other.

The classified as disturbed frequencies remain only a predetermined Time classified as disturbed. After this Time they are from the list of substances classified as impaired deleted frequencies and again assumed to be undisturbed.

The number of the list as disturbed classified frequencies basically is not limited. It proves in particular Cases, however, be advantageous if a forcibly minimum number of substances classified as undisturbed frequencies is maintained, this number minimum the 2.4 GHz ISM band is set to 75; thereby in time average a broad output spectrum produced. In the list can also be at regular or irregular certain intervals by a random undisturbed Frequencies are added. Thus, a avoiding synchronization of independent base stations will.

The handsets are designed to connect with the base station select a particular transmission / reception frequency, through which they receive the link to the base station want. Choosing this frequency occurs at comfortable Handsets using a field strength measurement (RSSI (Radio Signal Strength Indication) measurement); it selecting a frequency from the relevant handset is received without interference with high field strength. Thereby can be achieved with high probability that the first contact between the relevant handset and can the base station go smoothly vonstatten. In simple constructed handsets, the frequency on the the contact is to take place, also at random to be chosen.

At the frequency of whatever selected waiting for the handset, to a so-called sync bearer of the base station Will be received. The sync bearer is a predetermined (Synchronization) data word to the base station in Data transmission designed slots will be sent if and so long slots in question are not reserved for it, with to communicate in the base station is booked handsets. If after a predetermined period no sync bearer received been, the handset changes the receiving frequency and start the search again.

The sync bearer can multiply within the respective slots be transmitted. This allows a very high probability be prevented that the expected sync bearer is the only reason not receive, because the question is handset momentarily not switched to receive.

If the handset has received the sync bearer (this is in Agent according to at least about 0.5 s the case), it may be the base station in frequency follow. Together with the sync bearer Namely, at the same time transmit information from which the handset in question, the next K as transmission / reception frequency can determine frequencies to be used.

At a frame duration of 10 ms, the 90 are different Transmitting / receiving frequencies by skipped in less than one second. The consequence of this is that described by the Telecommunications device in the used or to Available frequency band in the temporal mean wideband output spectrum is generated. Disorders be due to permanent one and the same frequency or few different frequencies are used, are characterized reliable excludable.

Due to the fact that the transmitting / receiving frequency unlike the system described in the introduction is no longer slot by slot, but is only one frame at a changed and must be less or shorter slots can contribute to change provided and / or readjustment of the transmitting / receiving frequency will. Characterized the proportion of time per unit time (Pro Frame) is available for user data transfer, relatively and in absolute terms greater. This can be used in order the information to be exchanged in higher quality transferred or (while maintaining quality) more handsets be able to operate at the base station.

The telecommunication device described proves therefore not only in the interference, but also elsewhere be very beneficial