JP3044064B2 - Time diversity communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

The present invention is applied to a mobile radio communication system. The invention relates to the use of time diversity technology. The present invention relates to a time diversity technique in which a radio base station repeatedly transmits the same signal including an error detection code or an error correction code, and repeats until a mobile radio receiver can correctly receive the signal. The present invention is suitable for use in a radio selective calling system. In particular, the present invention relates to a technique for improving a reception rate in a poor transmission path condition.

[0002]

[Prior art]

An example of using a wireless receiver for receiving the same signal transmitted a plurality of times is a wireless selective calling system. Hereinafter, this radio selective calling system will be described. In the radio selective calling system, the same signal is transmitted a plurality of times, and when any one of them is received, the radio receiver is called when the received signal includes its own address. Is recognized, a ringing tone is emitted and a message is displayed. The signal is composed of a codeword of an error correction code or an error detection code. The principle of this conventional example will be described with reference to FIGS. FIG. 9 is a diagram showing words transmitted repeatedly. This is conceptually shown to make the explanation of the actual configuration of the call signal sequence easy to understand. FIG. 10 is a flowchart showing a conventional receiving procedure. As shown in FIG. 9A, the signal repeatedly transmitted n times includes k codewords as shown in FIG. 9B. The information content is the same for n times.

As shown in FIG. 10, when the number of receptions is n or less (S21), it is determined whether or not all codewords for one signal (k) have been correctly received (S22). If reception has not been successful, reception is repeatedly attempted within n times. As a result, if all the codewords for one signal (k) can be correctly received, it is determined that one signal has been received (S23), and the reception procedure ends. If it is not possible to correctly receive all the codewords for one signal (k) even after the reception is repeated n times, it is determined that one signal cannot be received and the reception is abandoned (S24). ), End the receiving procedure. At this time, at the time when the reception is completed n times before, the radio receiver suspends the reception operation until the arrival time of the next different n-times repeated call signal,
Reduce battery consumption.

In such a conventional receiving method, the probability of correctly receiving all (k) codewords for one signal is low in a poor quality mobile communication transmission path in which fading occurs.
There is a problem that the signal reception rate is reduced. Thus, Japanese Patent Application Laid-Open No. 63-290026 discloses a receiving method using time diversity reception. This time diversity receiving method will be described with reference to FIGS. FIG. 11 is a diagram showing a call signal sequence. FIG. 12 is a block diagram of a conventional apparatus. FIG. 13 is a flowchart showing a conventional time diversity reception procedure. As shown in FIG. 11 (1), the paging signal sequence is composed of a frame having a length of T and connecting r subframes. Also, as shown in FIG. 11 (2), each subframe signal is composed of mj paging signals, and each paging signal is composed of an address signal composed of p error correction code words and q error correction codes. The message signal is composed of the following codeword. Further, the radio receivers are divided into r groups, and the radio receivers belonging to group j are in the reception state only during the reception time of one subframe j. At this time, if the address signal of the calling signal in this subframe matches the address number of the wireless receiver, a ringing tone is emitted from the wireless receiver and a message signal following the address signal is displayed on the display unit. Call operation.

In this radio paging system, when a paging signal is transmitted a plurality of times in order to improve a paging signal reception rate, a code word of the same message signal received by retransmission, The time diversity reception process of comparing the error correction result for each message with the error correction result for the previously received message signal stored in the memory for each codeword, and selectively combining codewords detected as being correctly received. Do.

In the block diagram shown in FIG. 12, a signal received by an antenna 1 is input to a receiving unit 2, demodulated, and then input to a decoder unit 3. Error correction or error detection is performed for each codeword by the decoding unit 4 in the decoder unit 3. As a result, when an address signal addressed to itself is detected, the processing procedure shown in FIG.

When the number of receptions is n or less (S31), it is determined whether or not the address signal can be correctly received, and whether the address signal matches its own address number (S32). If they match, the error detection result of the currently received codeword is compared with the error detection result of the previous codeword stored in the memory 6 for each codeword of the message signal (S33), and the message is correctly received. The codeword is selectively synthesized (S34). Further, in the message signal after the selective combination, the error detection result for each codeword and the combined message signal are stored in the memory 6 (S35). It is determined whether all codewords for one paging signal have been received without error (S36). At this time, if the address signal cannot be received correctly, the control waits until the next retransmission of the call signal. If the call is successfully received, it is determined that the call signal has been successfully received (S37), and a ringing operation is performed from the speaker 9 via the drive unit 7 and a message signal is displayed on the display unit 8. If one or more incorrectly received codewords among the q codewords constituting the message signal are included, the process is repeated in the next signal reception. On the other hand, if the number of receptions is equal to or more than n + 1 times, it is determined that the paging signal cannot be received correctly, and the paging signal is abandoned (S38).

[0008]

[Problems to be solved by the invention]

This time diversity receiving method is an excellent method that can correctly receive a message signal even on a mobile communication transmission line of poor quality. However, the address signal is correctly received every retransmission, only when it is recognized that it is the same message signal for the same address signal, time diversity processing is performed, in a mobile communication transmission path of poor quality, Since the reception probability of the address signal is low, time diversity processing may not be performed, and a situation may occur where the paging signal reception rate cannot be improved. Further, in the proposal of the applicant of the present invention in Japanese Patent Application No. Hei 5-036963 (not disclosed at the time of filing of the present application), except for the reception timing of unreceived codewords, a part of the wireless receiver is suspended until n receptions thereafter. It is possible to However, if the signal reception rate is low, this effect cannot be expected.

The present invention has been made in such a background,
An object of the present invention is to provide a wireless receiver capable of further improving a reception rate.

[0010]

[Means for Solving the Problems]

The address signal and the message signal are each composed of a plurality of codewords, and a feature of the present invention is to execute time diversity reception for each codeword constituting a word without distinguishing the address signal or the message signal. is there. That is, the first aspect of the present invention is a time diversity communication system, which is characterized in that a codeword having the same content encoded according to the logic of error correction or error detection is transmitted as a radio signal over time. And a receiving device for receiving the codeword and decoding the information of the codeword according to the theory of error correction or error detection, the receiving device receives the same for multiple times There is provided a means for selecting, as reception information, codeword information determined to be more correctly decoded in accordance with the logic of error correction or error detection for the codeword of the content.

[0011] Furthermore, when the information of the codeword determined to be most correctly decoded according to the logic of error correction or error detection for the codeword of the same content received a plurality of times is obtained, It is desirable to have a means for prohibiting reception of the code word having the same content. Thereby, the consumption of the battery of the receiving device can be reduced.

[0012] A second aspect of the present invention is a receiving apparatus used for the time diversity receiving method. This receiving apparatus is, for example, a radio selective calling receiver. In a radio signal transmitted from the transmitting apparatus, a frame including a plurality of r subframes is repeatedly transmitted n times, and the jth (j ≦ r) The subframe includes mj paging signals, one of the paging signals including an address signal and a message signal, the address signal including p codewords, the message signal including q codewords, It is preferable that the receiving device receives the transmission signal and detects that the address signal matches the address set in itself.

[0013]

[Action]

The wireless receiver receives the repeatedly transmitted signal. The signal is divided into address signal areas and message signal areas, each of which is configured as a group of codewords. The present invention is characterized in that a signal is simply regarded as a group of codewords, and time diversity reception is performed for each codeword without distinguishing an address signal or a message signal.

The first transmitted signal is received, and the codeword is received without distinction between the address signal area and the message signal area. The codewords received not only include those correctly received, but also those containing errors and those containing errors but corrected. Further, there is a correction in which one bit is corrected or a correction in which two bits are corrected. The result is stored in the memory. Thereafter, this procedure is repeated for n transmissions. After the end of the n-th reception, if all the codewords can be correctly received, the reception is determined to be successful. At this time, it is not necessary to receive the codeword already correctly received in the first time from the second time onward, and if the other codewords are re-received at the second or later reception timing, the radio receiver Battery consumption can be reduced.

At the time when the reception is successful, an address signal is detected for the first time, and it is determined whether or not the address signal includes an address signal that matches the own address. As a result, if an address signal addressed to itself is included, it indicates that the call has been made, and further displays a subsequent message signal.

[0016]

【Example】

The configuration of the embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 2 is a block diagram of an embodiment of the present invention.

The present invention is a time diversity communication system, which is characterized in that a codeword having the same content encoded according to the logic of error correction or error detection is transmitted a plurality of times as a radio signal over time. A base station 20 as a transmitting apparatus, and a radio selective call receiver 11 as a receiving apparatus that receives the codeword and decodes information of the codeword according to error correction or error detection logic. The paging receiver 11 employs a decoder unit 3 for selecting, as reception information, a code word information which is determined to be more correctly decoded in accordance with the logic of error correction or error detection for a code word of the same content received a plurality of times. To prepare for.

Further, the radio selective call receiver 7 obtains information of a codeword determined to be most correctly decoded according to the logic of error correction or error detection for codewords of the same content received a plurality of times. In some cases, the decoder unit 3 is provided with a unit for prohibiting reception of the same codeword.

In the radio signal transmitted from the base station 20, a frame including a plurality of r subframes is repeatedly transmitted n times, and the jth (j ≦ r) subframe includes mj paging signals, One of the paging signals includes an address signal and a message signal, the address signal includes p codewords, the message signal includes q codewords, and the radio selective paging receiver 11 transmits the transmission signal. And detects that the address signal matches the address set for itself.

The principle of the embodiment of the present invention will be described with reference to FIGS. 2 and 3 are views for explaining the principle of the embodiment of the present invention. FIG. 2A shows the first reception signal, and FIG. 2B shows the second reception signal. “×” in the error detection result indicates a codeword in which an error was detected, and “○” indicates a codeword received correctly. First received signal and 2
The received signal is compared with the received signal of the second time, and a codeword that is correctly received is selected and combined. The results are shown in FIG. For the code word “1-6”, an error was detected both in the first and second times, so that the synthesis result also contains an error. For the code word "1-6", it is necessary to try to receive even the third and subsequent reception timings until the correct reception is performed.

FIG. 3A shows a first reception signal, and FIG. 3B shows a second reception signal. The "x" in the error correction result indicates a codeword for which an error has been detected but cannot be corrected, and "0",
The numbers “1” and “2” indicate the number of correction bits of the code word. In this, "0" indicates that no correction is required. The first reception signal and the second reception signal are compared, and the more accurate codewords among them are adopted and combined. The result is shown in FIG.
It is shown in (3). The smaller the number of correction bits, the lower the probability of occurrence of erroneous correction. Therefore, the one with the smaller number of correction bits is selected. Regarding the code word “1-6”, an error was detected both in the first and second times, but the error was uncorrectable, so the synthesis result also contains an error. For the code word "1-6", it is necessary to try to receive even the third and subsequent reception timings until the correct reception is performed. Also in this case, similarly to the description of FIG.
Codeword) "and" x ".

The operation of the embodiment of the present invention will be described with reference to FIG. FIG.
5 is a flowchart showing the operation of the embodiment of the present invention. This flowchart shows an operation adapted to the repeatedly transmitted signal shown in FIG. 9 in the conventional example. A signal received by the antenna 1 shown in FIG. The received signal demodulated by the receiving unit 2 is input to the decoder unit 3. The decoding unit 4 of the decoder unit 3 performs error correction or error detection for each codeword. The codeword after error correction or error detection and the error detection result are input to the processing unit 5.

As shown in FIG. 4, when the number of receptions is n or less (S 1), the processing unit 5 performs, for each code word, the error correction or error detection result of the currently received code word and the code stored in the memory. The word diversity is compared (S2), and a time diversity reception process for selecting and synthesizing a correctly received codeword is performed (S3).
Further, the error correction or error detection result in the codeword after the selective synthesis and the signal after the synthesis are stored in the memory 6 (S4). Subsequently, when all (k) codewords for one signal are received without error (S5), it is determined that one paging signal has been successfully received (S6), and the signal after the combining processing or the signal after the combining processing is received. Is output to the drive unit 7 and the process is terminated. When one or more incorrectly received codewords are included in the k codewords, this process is repeated in the next signal reception. On the other hand, when the number of times of reception is equal to or more than n + 1, the reception of this calling signal is abandoned, and the process is terminated (S7). Here, when all the codewords for one signal are received without error, it is also possible to suspend a part of the wireless receiver until receiving n times thereafter.

The embodiment of the present invention is characterized in that time diversity reception is performed for all codewords without distinction between address signals and message signals. If the address signal is not received correctly, this is different from the conventional example in which time diversity reception is not performed.

Next, an embodiment of the present invention will be described more specifically with reference to FIGS. FIG. 5 is a diagram showing a more specific paging signal sequence of the embodiment of the present invention. FIG. 6 is a flowchart showing the operation of the processing section 5 in a more specific paging signal sequence. When the paging signal is transmitted n times, in FIG. 5, each subframe is composed of a paging signal having the same transmission number, and a frame composed of paging signal subframes having the same transmission number is represented by n.
Will be sent twice. The location of the retransmitted paging signal is known at the wireless receiver.

When the number of receptions is n or less (S11), the error detection result of the currently received codeword is compared with that of the codeword stored in the memory 6 for each error correction codeword (S12). A time diversity receiving process for selectively combining the received codewords is performed (S13). Further, the error detection result after the code after the selective synthesis and the signal after the synthesis are stored in the memory 6 (S14). When an error is detected in one or more codewords in one subframe, this process is repeated (S15). Subsequently, when all codewords in one subframe are received without error, or the number of receptions is n + 1
If the number of times is equal to or greater than the number of times, it is determined whether or not the address signal matches the address number of the wireless receiver in the call signal that correctly receives all codewords for one call signal (S16). (S17) If they match, it is determined that a calling signal has been received (S18), and a calling operation is performed by emitting a calling sound from the speaker 9 via the drive unit 7 and displaying a message signal on the display unit 8. If they do not match, or if there is no paging signal that correctly receives all codewords for one paging signal, the process ends as paging signal non-reception (S19). Here, when all codewords in one subframe are received without error,
Thereafter, a part of the wireless receiver can be suspended until the reception is performed n times.

Next, a case where another call signal sequence is used will be described with reference to FIGS. 7 and 8. FIGS. 7 and 8 are diagrams showing another call signal sequence used in the embodiment of the present invention. In the paging signal sequence shown in FIG. 7, each subframe having a time length α is divided into transmission times r, and transmitted in order from subframe 1. This paging signal sequence has been proposed by the present applicant in Japanese Patent Application No. 5-012822. Here, time t0 + (j−1) ×
y-th subframe j transmitted to α (1 ≦ y
.Ltoreq.n-1) The calling signal group is at time t0 + T + (j-1) .times..alpha.
Are transmitted as the (y + 1) th paging signal group in the subframe j transmitted to the subframe j. Here, T is the signal length (period) of a frame composed of r subframes, and T = r
× α. The flow chart shown in FIG. 6 can be applied to this calling signal sequence.

The paging signal sequence shown in FIG. 8 is a paging signal in which a field of an address signal and a field of a message signal are separately configured. In the present invention, time diversity is performed for each codeword, and thus the address signal and the message signal can be accommodated in any position.

As described above, the paging signal can be subjected to the time diversity reception processing for both the address signal and the message signal, so that the paging signal reception rate can be improved.

[0030]

【The invention's effect】

As described above, according to the present invention, the reception rate can be further improved. As a result, it is possible to realize a wireless receiver that has a low call disable rate and consumes little battery. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of the embodiment of the present invention.

FIG. 3 is a diagram for explaining the principle of the embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 5 is a diagram showing a more specific paging signal sequence according to the embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of the processing unit using a more specific calling signal sequence.

FIG. 7 is a diagram showing another call signal sequence.

FIG. 8 is a diagram showing another call signal sequence.

FIG. 9 is a diagram showing a signal transmitted repeatedly.

FIG. 10 is a flowchart showing a conventional reception procedure.

FIG. 11 is a diagram showing a call signal sequence.

FIG. 12 is a block diagram of a conventional apparatus.

FIG. 13 is a flowchart showing a time diversity reception procedure of a conventional example.

[Explanation of symbols]

 1 antenna 2 reception unit 3 decoder unit 4 decoding unit 5 processing unit 6 memory 7 drive unit 8 display unit 9 speaker 10 address signal detection unit 11 radio selective call receiver 20 base station

Continuation of the front page (56) References JP-A-61-270935 (JP, A) JP-A-63-290026 (JP, A) JP-A-1-181250 (JP, A) JP-A-4-341020 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 1/02-1/06 H04B 7/02-7/12 H04B 7/26 H03J 3/00

Claims (8)

(57) [Claims] 1. A calling signal comprising an address signal and a message signal, wherein the address signal and the message signal comprise a plurality of codewords encoded according to error correction or error detection logic. A transmitting apparatus that encodes a paging signal and transmits the same content of the paging signal as a radio signal a plurality of times as time passes, and receives the paging signal including the plurality of codewords and performs error correction or error detection according to the logic thereof. A receiving device for decoding a code word, the receiving device performs error correction or error detection on the code word having the same content of the paging signal received a plurality of times without distinguishing the address signal and the message signal. , A codeword determined to be correctly decoded according to the logic of error correction or error detection as received information Time diversity over a communication system, characterized in that it comprises means for-option. 2. The method according to claim 1, wherein said selecting means comprises a code word having the same content of the paging signal received a plurality of times and having a minimum number of error correction bits among code words determined to be correctly decoded in accordance with the error correction logic. 2. The time diversity communication method according to claim 1, wherein said communication method is selected. 3. The receiving apparatus according to claim 1, wherein when a code word determined to be correctly decoded according to the logic of error correction or error detection is obtained for a code word having the same content of the paging signal received a plurality of times, 3. A device according to claim 1, further comprising means for prohibiting reception of the codeword having the same content.
The time diversity communication method described. 4. A receiving apparatus for use in a time diversity communication system according to claim 1. 5. The wireless signal transmitted from the transmitting device,
A frame including a plurality of subframes is repeatedly transmitted n times, the subframe includes a plurality of paging signals, the paging signals include an address signal and a message signal,
The address signal or the message signal includes a plurality of codewords, and the receiving device is a radio selective call receiver that receives the radio signal and detects that the address signal matches an address set in the radio signal. 4. The time diversity communication method according to any one of 1 to 3. 6. The radio signal transmitted from the transmitting device,
A frame including a plurality of subframes having the same time length is n
This subframe includes n paging signal groups each having a different number of transmissions, and the paging signal group having the number of transmissions “n” in the subframe transmitted in the previous transmission cycle is transmitted in the current transmission cycle. 4. The time diversity communication method according to claim 1, wherein a paging signal group having a transmission frequency of "1" including a new paging signal is inserted into the subframe, and the paging signal group including a new paging signal is inserted into the subframe. . 7. A plurality of paging signal groups each including a plurality of paging signals, the paging signal including an address signal and a message signal, the address signal or the message signal including a plurality of codewords, The time diversity communication system according to claim 6, wherein is a radio selective call receiver that receives the radio signal and detects that an address signal matches an address set in the radio signal. 8. A radio selective call receiver for use in a time diversity communication system according to claim 5.