WO1999049672A1

WO1999049672A1 - Method for adapting a receiver to transmission conditions and receiver for carrying out the method

Info

Publication number: WO1999049672A1
Application number: PCT/DE1999/000623
Authority: WO
Inventors: Ralf Hartmann; Peter Bohnhoff
Original assignee: Infineon Technologies Ag
Priority date: 1998-03-26
Filing date: 1999-03-09
Publication date: 1999-09-30
Also published as: DE19813507A1; DE19813507C2

Abstract

The quality of bursts of a redundant code which have been received is used to ensure that only a minimal number of bursts need be received within a frame for message decoding. If it is possible to receive a minimal number of bursts in order to decode a message, essential functional groups of the receiver are put into an energy-saving mode for the remaining period of the message block.

Description

description

Process for adapting a receiving device to transmission conditions and receiving device therefor

The present invention relates to a method for adapting a receiving device to transmission conditions according to the features of the preamble of claim 1 and a receiving device therefor according to the features of the preamble of claim 1.

For network-independent receivers, such as. B. Pager or cell phones that can work according to the GSM standard, special emphasis is placed on low power consumption in order to ensure the longest possible operation with a battery or an accumulator charge. Efforts are therefore made to separate function groups of the receiving device that are not required as long as possible from the supply voltage in order to reduce the average power consumption.

For devices that work in a radio network with time division multiplex organization, there is a standby mode, also called standby mode, and, for example, all function groups that are not required can be periodically disconnected from the power supply in order to reduce the average energy requirement.

The transmission technology of modern mobile radio networks, such as. B. the GSM network, uses highly redundant codes to reduce the influence of interference, and thus to increase the traffic performance of a system with otherwise fixed specifications, such as frequency range, number of base stations, transmission power, etc. However, data processing, in particular decoding to restore the original message, requires considerable computing effort, which in turn entails high power consumption. On the other hand, the devices and the codes used are designed for the given, worst possible case of the transmission conditions, which is only occasional in practice, so that it is uneconomical to operate the devices continuously with full computing effort for data processing / decoding and thus unnecessarily to consume a lot of electricity

Based on this knowledge, z. As described in EP 496 152 A2, during operation of a mobile radio device with an equalizer operating according to a Viterbi algorithm, the number of states of the algorithm can be flexibly adapted to the actually measured duration of multipath interference.

A solution to this problem is also given in the previously unpublished patent application 196 39 887.8 by the applicant. The method specified therein is exemplified for the GSM standard and works as follows.

An uncoded information block in the control channel CH consists of 184 bits, which is expanded to 456 bits by fire coding (40 parity bits) and convolutional coding (inserting tail bits, rate = 1/2) and then distributed to four bursts in the TDMA frame grid by interleaving . The high redundancy is only fully utilized in very bad transmission conditions, so it makes sense to start a decoder run after receiving, equalizing and deinterleaving the first two bursts of an information block (Viterbi convolution decoder and fire encoder). The equalizer does not make a hard decision on the information output, but determines a number for each bit as a measure of the probability that zero or one was sent (soft decision equalizer). The soft decision value of the bits of the bursts not yet received is set to "indeterminable", ie the equalizer could not distinguish between zero and one. Should the decoder run with the first two bursts of an in- 3 formation blocks are unsuccessful, another burst is received and a decoder run with three bursts is started. If this decoder run is also unsuccessful, the last burst of the information block is received and the decoder run is started with the complete block. If the early decoding with two or three bursts is successful, then for the remaining two bursts or the remaining one burst all the reception groups that are not required are switched into a power-saving module, in particular separated from the power supply.

However, this described method has the disadvantage that even with poor and medium transmission conditions, decoder runs are started with only two of a total of four bursts, and power is therefore unnecessarily used for unsuccessful decoder runs.

The invention is therefore based on the object of specifying a method and a receiver working according to these methods of the type mentioned, which by adapting the number of decoding bursts to the quality of the received bursts and thus to the transmission conditions in accordance with the reduction in the mean computing effort and thus enable electricity consumption.

This object is achieved for the method by a method with the features of claim 1 and for the receiving device by a receiving device with the features of claim 7.

The invention thus takes advantage of the fact that the full

Redundancy of the code used over long periods is in no way required and uses this to save energy, as a result of which a longer standby operation can be achieved.

It is advantageous if the minimum number of bursts required for early decoding is dependent on 4 is determined by at least one threshold value dependent on the sum of the burst qualities.

If the total number of present bursts is four, the minimum required number of bursts to be decoded is set to two when a first threshold value dependent on the sum of the burst qualities is exceeded, while when a second threshold value is exceeded the minimum required number of bursts to be decoded is set to three is set.

In a preferred variant, the information of the message block is encoded by means of a fire code and a convolutional code.

The invention can also be used advantageously in cases in which the message is paging information and the method is carried out in paging mode.

Furthermore, the object for a receiving device of the type mentioned at the outset is achieved in that the decoder is set up to decode only a minimum number of bursts of each message block which is required in accordance with the redundancy of the coding used, as long as a control assigned to the decoding and the test unit determines that the decoding is successful and delivers the required message, the control and test unit being designed to determine the minimum number of bursts required for the first or early decoding by evaluating the equalizer contained in the receive logic block burst quality determined determined, and wherein the control and test unit after decoding separates the functional groups from the power supply and the control and test unit causes the decoder to decode a larger number of message bursts, if the decoding of these minimal Number of bursts the message could not deliver. It is advantageous if the minimum number of bursts required for early decoding can be determined as a function of at least one threshold value which is dependent on the sum of the burst qualities.

In the case in which, as with GSM, the total number of bursts is four and approximately 50% redundancy is transmitted as error protection, it is preferred if the first threshold value dependent on the sum of the burst qualities is exceeded, the minimum number of bursts to be decoded is two to be set, while if a second threshold value is exceeded, the minimum required number of bursts to be decoded is set to three.

According to a preferred embodiment of the invention, the decoder and the control and test unit are set up to evaluate the frame or burst received immediately after receiving and evaluating the minimum required number of bursts of each message block in the event of unsuccessful decoding.

According to a further embodiment of the invention, the decoder is set up to decode the information of the message block that is present in a form coded by means of a fire code and a convolution code.

If the message is paging information, the logic and control block can, according to a further embodiment, switch off essential functional groups in the paging mode between the paging information.

Further advantageous embodiments are specified in additional subclaims. 6 The present invention will be described in more detail below using an embodiment with reference to the single figure. It shows:

Fig. 1 is a block diagram of the receiver part of a mobile radio receiving device according to the invention

The invention is explained below with particular reference to a mobile radio network in the GSM system. This system works with a TDMA frame structure, more precisely e.g. B. "Mobile Radio Communications", Raymond Steele, IEEE Press New York. Reference is expressly made to this and other documents mentioned here in connection with the disclosure of the application. The coding and channel interleaving are also described in the "GSM Recommendations, Draft prETS 300 575, March 1995 (GSM 0.5 03 Version 4.2.0) and the books on the theory of fire codes and other codes are" Prüfe are and correctable codes "W. Wesley Peterson, R. Oldenburg Verlag 1967 and" Wireless Digital Communications, Modulation and Spread Spectrum Applications ", Dr. Kamilo Feher, Prentice-Hall PTR.

As shown in the figure, an RF receiving block (HEB) processes an incoming signal at the antenna and supplies the I / Q components of this baseband signal to two analog / digital converters ADC. An equalizer EQU connected downstream of these analog / digital converters ADC receives the converted signals and passes the burst qualities determined by it to a control and testing unit SPE. The control and testing unit SPE then decides whether an early decoder run is expedient, a decoder DEC being activated by the control and testing unit SPE if necessary.

If the decoder run is successful, the signal is processed further and sent to a logic and control block LSB. 7 sets. This logic and control block LSB can then switch off the HF reception block HEB and parts of the baseband processing.

If the decoder run is unsuccessful and fewer than four bursts have been processed in the decoder DEC, another burst is received and a new decoder run is started.

If a decoder run with four received bursts is not possible, the decoded information block is considered to be faulty.

As already stated at the beginning, the method described there has the disadvantage that even with poor and medium transmission conditions, decoder runs are started with only two of a total of four bursts, and power is therefore unnecessarily used for unsuccessful decoder runs.

The equalizer or soft decision equalizer EQU provides a measure of the transmission ratios or burst qualities. The equalizer information usually consists of a so-called hard decision (zero or one) and so-called soft information as a measure of the reliability of the hard decision.

The higher the amount of this soft information, the more reliable this hard decision is. The sum of the soft information of all bits per burst is therefore a measure of the transmission ratios and the quality of the equalization of the received burst.

A large amount stands for reliable equalization of the burst and thus for good transmission ratios. A small amount stands for an unreliable equalization of the burst. By evaluating these burst qualities in the control and testing unit SPE, it is possible, however, to make a statement as to whether an early decoder run with two or three bursts is promising or whether a further burst must be received beforehand.

If the total number of the present bursts is four, an early decoder run with two equalized bursts makes sense if both the burst qualities determined by the equalizer EQU as a sum exceed a certain threshold value or a certain threshold ZI.

However, if the sum of the burst qualities of three bursts exceeds a certain threshold or a certain threshold Z2, an early decoder run with three equalized bursts makes sense.

The thresholds ZI and Z2 are dependent on the determination of the soft decision information.

This evaluation logic of the burst qualities must also be implemented in a receiving device, the only figure representing this integration as a block diagram.

According to the invention, the number of unsuccessful decoder runs can be reduced. For the example of CCH in GSM with the coupling of convolutional code and fire code, the specified procedure proves to be extremely useful.

The invention has been described above in connection with the receiving part of a mobile radio device, but it is clear that it can also be used in connection with other receiving devices which operate in a system with a correspondingly redundant code. For example, these can be pager receivers, or also digital, battery-operated radio or television receivers, in which minimizing the power consumption is also desirable, ie The invention is not limited to cases in which there is a paging operation, and the processing of the information according to the invention can concern any message.

In summary, the invention can be described as follows. Operation of a TDMA receiving device, e.g. B. a mobile radio device is adapted to the current transmission conditions. A redundantly coded message is used here, which is contained as a message block in bursts of n frames of a message frame sequence. According to the invention, the burst qualities are evaluated and, depending on this, an early decoder run is carried out to evaluate a minimally necessary number of bursts. For the period after decoding information of a message block, essential functional groups of the receiving device are brought into a power-saving mode (power supply interruption, clock switch-off).

Claims

10 claims

1. Method for adapting a receiving device to the transmission conditions, with redundantly coded information in the form of message blocks each having a plurality of bursts being transmitted and the receiving device attempting to decode the information after receiving minimally necessary bursts within the message block in order to ensure that the rest - Chen period to switch function groups of the receiving device into a power saving mode, characterized in that the respective burst quality of a predetermined number of bursts is determined and, depending on these burst qualities, it is determined whether an early decoder run for decoding the transmitted information is carried out.

2. The method according to claim 1, characterized in that the burst quality is determined by a soft decision equalizer, in that the sum of the soft information of all bits per burst is determined and the value determined from this is compared with a threshold value, depending on whether this is exceeded or not Threshold value, the function groups of the receiving device are switched to the power saving mode.

3. The method of claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the power saving mode is realized by a power supply interruption and / or a clock shutdown.

4. The method according to any one of claims 1 to 3, characterized in that the total number of bursts within a message block is four and when a first threshold value (ZI) dependent on the sum of the burst qualities is exceeded. 11 the minimum required number of bursts to be decoded is two, while if a second threshold value (Z2) is exceeded the minimum required number of bursts to be decoded is three.

5. The method according to any one of claims 1 to 4, so that the uncoded information of the message block is encoded by fire coding and / or convolutional coding.

6. The method according to any one of claims 1 to 5, so that the uncoded information is paging information and the method is carried out in paging mode.

7. receiving device, with an RF receiving block (HEB), a receiving logic block (ELB), a logic and control block (LSB) and a power supply, the logic and control block (LSB) being set up to, if necessary, essential functional groups of the Switching the receiving device into a power saving mode, characterized in that a control and test unit (SPE) is provided for determining and evaluating the burst qualities of the bursts received in each case and for activating the decoder (DEC) contained in the receiving logic block (ELB) as soon as the Burst quality is determined to be sufficiently good.

8. Receiving device according to claim 7, so that an activation of the decoder (DEC) depending on the comparison result of a predetermined threshold value (71) with the value of the sum of at least two burst qualities can be determined.

12. Receiving device and claim 7 or 8, characterized in that the total number of bursts is four and when a first threshold value dependent on the sum of the burst qualities (ZI) is exceeded, the minimum required number of decoded bursts is two, while when exceeded a second threshold (72), the minimum required number of bursts to be decoded is three.

10. Receiving device according to one of claims 7 to 9, so that the decoder (DEC) is set up to decode the information of the message block present in a form coded by means of a fire code and a convolutional code.

11. Receiving device according to one of claims 7 to 10, so that the message is paging information and the logic and control block (LSB) is set up to switch off individual function groups in the paging mode between the paging information.