Method for communication using a half duplex radio channel in a radio network

p0001The invention relates to a communication method for a radio network, with at least two participants, one radio channel is indeed used in both directions between the participants, but this is always and only in succession in one and then in the other direction, that is not the same in both directions wherein the subscribers each sensor dezeitpunkte be specified to which a participant must send the other party a Nutztelegramm in a time frame.

p0002In various communications applications for data exchange is only a single radio channel. In this case, the half-duplex method used. Here messages are sent only in succession in one direction or another. The simultaneous use of such a spark gap in both directions would lead to collisions and must therefore be avoided. To prevent such collisions, takes place at the "polling" a polling. This will be sent, for example, from a master to a slave of a communication network in one direction a query and the slave then responds with the ends over a present Nutztelegramms in the other direction. In the absence of utilization data, this can be communicated in the response telegram. In this half-duplex procedures are reserved for the queries and reply telegrams correspondingly long times, which for many queries, long reaction times result has.

p0003From International Application <patcit id="pcit0001" dnum="WO0241520A2"><text>WO 02/41520 A2</text></patcit> discloses a method that transmits the data between a base station and multiple mobile stations using TDD frame and the mobile stations are informed about a check array scheduling information in the downward direction when data transmissions in the upward direction are specify possible.

p0004The invention is therefore based on the object to improve a method of the aforementioned kind such that the shortest possible response times are achieved.

p0005The object is achieved with a method having the features of Claim 1. In this case, a detection signal is in each Nutztelegramm embedded at the beginning or such a detection signal precedes the Nutztelegramm, and the detection signal is used to inform the receiving subscriber, the assignment of the radio link. A participant will only send out one Nutztelegramm the allowable transmission time if no detection signal has been received by the other party. The time interval from a transmission time point in the time pattern which is to transmit a Nutztelegramms assigned to a subscriber, to the next transmission time point in the time pattern which is to transmit a Nutztelegramms assigned to the other party, is determined by the duration of the detection signal on the radio link between two subscribers , By applying the detection signal to a performant information transmission with single-channel radio link can be achieved than by the half-duplex method hitherto known. This embodiment allows particularly short response times.

p0006Advantageous developments of the invention are disclosed in claims 2 to 10th

p0007It is advantageous if, according to claim 2, the said one subscriber predetermined transmission time points for emitting a Nutztelegramms compared to the transmission times, which are provided to the other party for transmitting a Nutztelegramms, time-synchronized.

p0008A further advantageous embodiment of the invention is achieved when according to claim 3, the transmission timings for sending out a Nutztelegramms be given the two participants in each case by a time line with a time frame that is determined by the time interval.

p0009To ensure reliable transmission of the detection signal, it is particularly advantageous if, according to claim 4, the detection signal is at least partially bit-coded.

p0010An embodiment of the invention is illustrated by a drawing. Show it:<dl id="dl0001" compact="compact"><dt>1 shows</dt><dd>a block diagram of a test station for Fahrzeugdiag- nose with the communication method of the invention over a radio channel and</dd><dt>FIG 2</dt><dd>a time line with a time frame for the inventive communication method.</dd></dl>

p0011<figref idrefs="f0001">1 shows</figref> shows a radio channel F between two subscribers A and B. The radio channel F can only be used successively in one and then in the other direction to avoid collision with the communication. In the present embodiment, the radio channel F is used for vehicle diagnostics. The subscriber A is therefore connected to an evaluation C and B of the device is connected to, for example, via a diagnostic connector to a vehicle. The subscriber B receives the vehicle data and sends it over the radio channel F to the subscriber A, which forwards this to the evaluation unit C for evaluation. After evaluation of the vehicle data in the evaluation unit C, the subscriber may receive a default to change a setting on the vehicle B via the radio channel F.

p0012The case applicable communication method of the invention allows both parties to send A and B equally Nutztelegramme to the other party B or A without long reaction times. To this end, both parties A and B are each given transmission times in a time frame to which a participant A or B the other party must send a B or A Nutztelegramm. These transmission times are starting times for the dispatch of Nutztelegramme. In order to avoid collisions, it is ensured in accordance with the communication method of the invention that the respective transmission time of the subscriber A or B of the radio channel F is not currently occupied by the respective other subscriber B or A. The information about the availability will be based on a detection signal that is embedded in the beginning of Nutztelegramms or preceded by the Nutztelegramm. A participant A or B is allowed to send to an associated transmission time one Nutztelegramm, if at that time by the other party B or A no detection signal has been received, which also means free that the radio channel F not currently occupied and for sending a Nutztelegramms is. The duration of the detection signal over the radio channel F from one to the other participants essentially determined the time interval t from a transmission time point Z in the time pattern which is to transmit a Nutztelegramms assigned to a subscriber A or B to the next transmission time point Z in the time slot. This time frame is the time intervals t on a timeline according<figref idrefs="f0001">FIG 2</figref> shown. The detection signal is advantageously at least partially bit-coded and enables the rapid detection of the busy state.

p0013The said one subscriber (A or B) predetermined transmission times (Z) for emitting a Nutztelegramms are compared to the transmission times (Z), which are the respective other subscriber (B or A) specified for emitting a Nutztelegramms, time-synchronized.

p0014This is for example in accordance with two time rulers with the same time frame. <figref idrefs="f0001">FIG 2</figref> achieved, wherein a subscriber (A or B) specifies the time ruler and the other subscriber (B or A) adjusts its time ruler of default. The time ruler predetermining participant only in this respect a master function. Otherwise, both parties are equal in the above described communication method.