JP2019092231A - Communication device, terminal, control station, communication system, program, and control method - Google Patents

Abstract

To provide a coverage extension technology for identifying an amount of a resource that enables communication without unnecessarily wasting the resource.SOLUTION: A communication device for communicating with another communication device detects a signal from the other communication device to identify an amount of a resource to be used in performing communication of a given amount of data from the other communication device to the communication device; transmits to the other communication device one predetermined signal corresponding to the identified amount of the resource from a plurality of predetermined signals that are already-known by the communication device and the other communication device and individually correspond to mutually different amounts of resources including at least either of a frequency and time to be used in performing communication of a given amount of data; uses an amount of a first resource to be used in performing communication of a given amount of data from the communication device to the other communication device to identify one predetermined signal corresponding to a combination of the amount of the first resource and an identified amount of a second resource from the plurality of predetermined signals; and transmits the one predetermined signal to the other communication device.SELECTED DRAWING: Figure 8

Description

  The present invention relates to coverage extension technology in wireless communication.

  In recent years, in a cellular network, it has been studied to cope with a low cost and low power consumption terminal for performing only a small amount of data communication (Non-Patent Document 1). Such a terminal is considered to be used, for example, for acquiring some observation data related to a natural phenomenon, monitoring a state of some apparatus, and the like. And, such terminals may not be able to cope with the coverage of a normal cellular network since they are not necessarily present in the range where people usually enter.

  In Non-Patent Document 1, it is considered to extend coverage in preparation for such a case. For example, coverage may be extended by the transmitter repeatedly transmitting the same signal. In this case, even if a single signal is transmitted, the receiver does not successfully receive the signal (that is, even if it can not acquire the content of the signal by demodulation etc.), the gain by its repetition , Can be received successfully. By this means, it becomes possible for a terminal that is originally in a range where it can not communicate to communicate with the base station.

3GPP TR 36.888 V12.0.0, June 2013

  When extending coverage, some resources will be used redundantly. That is, for example, in the case where repetitive transmission of a signal is performed, at least one of frequency and time resources is used for transmission of one data by the number of times of repetitive transmission compared to one transmission. . Here, if the communication device repeatedly transmits data for an excessive number of times in order to ensure that it can communicate with other devices, it leads to wasted resources, but if the number is insufficient, communication will eventually result. It will not be possible. Therefore, in such coverage extension techniques, it is important to identify the amount of resources that can communicate without unnecessarily wasting resources.

In order to achieve the above object, a communication device according to the present invention is a communication device that communicates with another communication device,
Specifying means for detecting a signal from the other communication device and specifying an amount of resource used when performing communication of a fixed amount of data from the other communication device to the communication device; the communication device and the other A plurality of predetermined signals which are known in the communication device, and which respectively correspond to different amounts of resources including at least one of frequency and time used when performing communication of a fixed amount of data from the signal, have a, and transmitting means for transmitting to the other communication apparatus to one predetermined signal corresponding to the amount of a particular resource in the specifying unit, the transmission unit, the other from the communication device Combining the amount of the first resource and the amount of the second resource specified by the identifying unit using the amount of the first resource used when performing communication of a fixed amount of data to the communication device of The one predetermined signal corresponding specified from the plurality of predetermined signal to transmits the one predetermined signal to the other communication apparatus.

Further, to achieve the above object, a terminal communicating with a control station according to the present invention is used when detecting a signal from the control station and communicating a certain amount of data from the control station to the terminal A specific means for specifying the amount of resources, and a plurality of predetermined signals known in the terminal and the control station, the resources including at least one of frequency and time used when performing communication of a fixed amount of data And transmitting means for transmitting one predetermined signal corresponding to the amount of resources specified in the specifying means from the plurality of predetermined signals respectively corresponding to different amounts, to the control station, The transmitting means uses the amount of the first resource used when performing communication of a certain amount of data from the terminal to the control station, and the second amount specified by the first resource and the specifying means. of The one predetermined signal corresponding to the combination of the amount of the source to identify from the plurality of predetermined signal, and transmits the one predetermined signal to the control station.

  According to the present invention, in the coverage extension technique, it is possible to specify the amount of resources that can be communicated without unnecessarily wasting resources.

The figure which shows the structural example of a radio | wireless communications system. The figure which shows the hardware configuration example of a radio control station and a terminal. The figure which shows the function structural example of a terminal. FIG. 2 is a diagram showing an example of a functional configuration of a radio control station. FIG. 10 is a schematic view showing the correspondence between the number of times of repeated transmission and the preamble ID used when gain is obtained by repeated transmission. FIG. 7 is a schematic view showing the correspondence between the number of times of repeated transmission and the number of times of retransmission and the preamble ID used when changing transmission power at the time of retransmission of repeated transmission. The figure which shows the example of the flow of the resource amount specific process in uplink communication. The figure which shows the example of the flow of the resource amount specific process in downlink communication. The figure which shows the example of the flow of the resource amount specific process in uplink and downlink communication. FIG. 7 is a diagram showing an example of preamble IDs that can be used in resource amount identification processing in uplink and downlink communication.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

(Configuration of wireless communication system)
FIG. 1 shows an example of the configuration of a wireless communication system according to the present embodiment. The wireless communication system includes, for example, a terminal 101 and a wireless control station 102 each operating as a wireless communication device. Although a system including one terminal 101 and one radio control station 102 is illustrated as an example, a plurality of these communication devices may exist. The radio control station 102 is, for example, a base station apparatus. Further, the present wireless communication system is, for example, a cellular communication system such as Long Term Evolution (LTE), but may be a cellular communication system of a later generation or a wireless communication system such as a wireless LAN. That is, the following techniques can be applied when using any technique for extending the communicable range between two communication devices, and the subject is not necessarily limited to a specific system such as a cellular communication system.

  In the present radio communication system, the radio control station 102 or the terminal 101 repeatedly transmits the same data a plurality of times, and the receiving apparatus transmits the data according to the gain obtained by transmitting the same data a plurality of times. Can be received. Here, "the same data is transmitted a plurality of times" does not necessarily mean "the same signal is transmitted a plurality of times". That is, the same data may be transmitted multiple times by the same signal, or may be transmitted multiple times by, for example, multiple different signals formed by applying different encoding techniques to the same data. Good. That is, "the same data" refers to data to be transmitted, and the signal itself for transmitting the same data and the content (for example, a bit string after encoding / decoding before) transmitted by the signal are transmitted for each transmission. It may be different. Here, as described above, when the transmitting device transmits the same data more times than necessary, at least one of frequency and time resources (for example, resource blocks) is wasted. Furthermore, for example, when the terminal transmits a signal for an excessive number of times, the power consumption increases, and the demand for low power consumption can not be met. On the other hand, if the number of repetitions of data transmission is too small, communication can not be performed. At this time, the resources used for the communication attempt are also wasted.

  For this reason, in the present wireless communication system, a method for identifying an appropriate amount of resources used for communication between the wireless control station 102 and the terminal 101 is introduced. Also, at that time, the radio control station 102 that controls communication can know the information. Here, the "appropriate amount of resources" is the amount of resources that "be able to communicate" and "do not waste too much resources" "on the communication of a fixed amount of data". That is, in general, when the amount of data to be transmitted is large, the amount of resources naturally also increases, but the amount of resources is specified as an amount not influenced by such amount of data. The “fixed amount” may be, for example, the amount of data transmitted in periodic communication between the terminal 101 and the radio control station 102, or, for example, the amount of data equivalent to one resource block in LTE. May be

  The amount of resources is, for example, the minimum repetition necessary for the radio control station 102 to successfully receive the preamble of the random access channel transmitted by the terminal 101 (that is, to identify what preamble has been transmitted). It is defined as the number of transmissions. In addition, the amount of resources may be defined as a combination of a minimum access frequency required for the radio control station 102 to receive successfully and a transmission power, for the preamble of the random access channel transmitted by the terminal 101. Note that the amount of resources may be defined by something other than the number of times of repeated transmission. For example, the amount of resources may be defined by the spreading factor when spreading transmission of one data. In this case, for example, the transmitting side apparatus can spread data before transmitting, and transmit the data after spreading using a plurality of resource blocks, and in the receiving side apparatus, the higher the spreading factor, Gain to receive signals transmitted from a distance.

  In this embodiment, the amount of resources to be used in data communication is specified by detecting in the receiving side apparatus a preamble of a random access channel transmitted by the terminal 101 or a broadcast signal transmitted by the radio control station 102. . Note that these signals are an example, and signals other than the preamble of the random access channel and the broadcast signal may be used to specify the resource amount. For example, any channel defined in 3GPP (3rd Generation Partnership Project) may be used. Also, the terminal 101 detects a broadcast signal transmitted by the radio control station 102, specifies the amount of resources to be used in downlink, and notifies the radio control station 102 of the result. The terminal 101 can use the preamble of the random access channel in this notification.

  Hereinafter, an example of the configuration of the terminal 101 and the radio control station 102 and an example of the flow of processing to be executed will be described with reference to FIGS.

(Hardware configuration of radio control station and terminal)
FIG. 2 is a diagram showing an example of the hardware configuration of the radio control station 102 and the terminal 101. As shown in FIG. The radio control station 102 and the terminal 101 have a hardware configuration as shown in FIG. 2 in one example, and have, for example, a CPU 201, a ROM 202, a RAM 203, an external storage device 204, and a communication device 205. In the radio control station 102 and the terminal 101, for example, programs for realizing the respective functions of the radio control station 102 and the terminal 101, which are recorded in any of the ROM 202, the RAM 203 and the external storage device 204, are executed by the CPU 201. Then, the radio control station 102 and the terminal 101 control the communication device 205 by, for example, the CPU 201 to perform communication between the radio control station 102 and another radio control station or between the radio control station 102 and the terminal 101. .

  In FIG. 2, although the radio control station 102 and the terminal 101 have one communication device 205, for example, the radio control station 102 may communicate with the communication device between the radio control stations and the terminal 101. May have a communication device. Also, the terminal 101 may have, for example, a plurality of communication devices corresponding to each of a plurality of frequency bands. The terminal 101 may have, for example, a communication device for receiving an uplink signal for direct communication between the terminals, and has a communication device for transmitting a downlink signal. It may be done.

  The radio control station 102 and the terminal 101 may be provided with dedicated hardware for executing each function, or may execute part of the hardware and execute the other part with a computer that operates the program. Good. Also, the radio control station 102 and the terminal 101 may execute all the functions by a computer and a program.

(Functional configuration of terminal)
FIG. 3 is a diagram showing an example of a functional configuration of the terminal 101. As shown in FIG. The terminal 101 has, for example, a transmitter 301, a receiver 302, a used resource amount determiner 303, and a preamble ID acquirer 304 as its functional configuration.

  The transmission unit 301 is a functional unit for transmitting a signal to the radio control station 102 by, for example, repeatedly transmitting the same data signal one or more times. In addition, when the terminal 101 exists in the coverage area of the radio control station 102, the transmitting unit 301 normally transmits the data signal once, and the terminal 101 does not exist in the coverage area of the radio control station 102, If coverage extension is required, the data signal is transmitted multiple times. Note that the transmitting unit 301 performs predetermined random access corresponding to the amount of resources to be used for uplink or downlink communication, which is determined or specified by the used resource amount determining unit 303 described later, for the radio control station 102. Send the channel's preamble. The specific method will be described later.

  The receiving unit 302 is a functional unit that receives, for example, a data signal transmitted one or more times from the radio control station 102, and acquires the content of the data. In addition, when the terminal 101 exists in the coverage area of the radio control station 102, the receiving unit 302 can usually acquire data included in the signal by receiving the data signal only once. On the other hand, when the terminal 101 does not exist in the coverage area of the radio control station 102 and coverage extension is required, the receiving unit 302 receives the data signal multiple times and acquires data.

  The used resource amount determination unit 303 determines the amount of resources used when the terminal 101 transmits a signal, and specifies the amount of resources required to acquire data from the signal transmitted by the radio control station 102.

  The used resource amount determination unit 303 can uniquely determine the amount of resources used when the terminal 101 transmits a signal. The used resource amount determination unit 303 initially determines to transmit each data signal only once, when the amount of resources is the number of times of repeated transmission of the signal, for example. After that, when it is determined that the radio control station 102 fails to receive the data signal, for example, no ACK is transmitted from the radio control station 102 after the signal transmission, the use resource amount determination unit 303 increases the number of times of repeated transmission. Thereby, the use resource amount determination unit 303 improves the reception success probability of the data signal in the radio control station 102. That is, the use resource amount determination unit 303 tries to obtain an effect of extending the coverage of the radio control station 102 by increasing the number of transmissions of the data signal. In general, by gradually increasing the amount of resources to be used, it is possible to gradually improve the probability that the radio control station 102 can receive data signals. At this time, when the lowest number of times of signal transmission is obtained by the external input at this time, the amount-of-use resource determination unit 303 determines the number of times of signal transmission regardless of whether the radio control station 102 transmits ACK. Repeated transmission may be performed. That is, the initial number of repetitions of the signal transmission need not be one, and the signal may be repeatedly transmitted from the beginning (and possibly always) multiple times.

  Note that the number of repetitions of signal transmission may be associated with the gain (dB) obtained by the repetition transmission. Here, the value of gain to be obtained may be a discrete value, for example, a value in 5 dB steps. In this case, the used resource amount determination unit 303 tries, for example, one data transmission in which the gain is initially 0 dB, and if it fails, attempts to transmit data for the number of times that gain of 5 dB can be obtained. , May attempt to transmit data as many times as gain of 10 dB is obtained.

  Here, although the case where transmission is repeatedly used as a method of obtaining a gain will be described, the gain obtained and the transmission method may be associated also when a method other than repetition transmission is used. The method of obtaining the gain may be other than repetitive transmission as well in each of the following descriptions.

  Further, the used resource amount determination unit 303 specifies, for the signal received repeatedly by the radio control station 102, whether the signal has been successfully received (that is, data related to the signal has been acquired) at the time of reception. can do. The radio control station 102 may repeatedly transmit a broadcast signal including, for example, a system information block (SIB) and the like, and the terminal 101 may obtain the content of the broadcast signal by receiving the broadcast signal one or more times. it can. Then, in this case, the used resource amount determination unit 303 specifies the number of times of acquisition of the content of the notification signal.

  For example, the preamble ID acquisition unit 304 acquires, from the radio control station 102, information (preamble ID) for specifying a plurality of preamble patterns of the random access channel each corresponding to the amount of resources used. An example of the information acquired here is shown in FIG. In the case of FIG. 5C, in the case where repeated transmission is not performed, such as preamble ID: A, preamble ID: B for three repeated transmissions, and preamble ID: C for five repeated transmissions, etc. Different IDs are assigned to the number of repeated transmissions. Note that FIG. 5C is only an example, and the preamble ID must not be assigned every odd number of times such as once, three times, five times, etc., and the preamble ID is respectively assigned to various repetition times. Can be assigned.

  The preamble ID acquisition unit 304 may acquire information on the correspondence between the amount of resources used and the preamble ID by receiving the broadcast signal transmitted by the radio control station 102, or may acquire it by another signal. Good. Also, the information on the correspondence between the amount of resource used and the preamble ID may be notified from the radio control station 102 to the terminal 101 only once if there is no time change. Also, the information on the correspondence between the amount of resource used and the preamble ID may change with time, and the terminal 101 monitors the signal transmitted from the radio control station 102, and when there is a change, it internally changes. The stored correspondence may be updated.

  The preamble ID may be designated by an individual preamble ID, or may be designated by a group ID that designates a group of a plurality of preambles. For example, in the case of FIG. 5C, the preamble IDs A, B, and C can be notified, respectively, in the cases where the number of times of repetitive transmission is 1, 3 and 5 respectively. Also, when a group including A, B and C is defined in advance as a preamble ID for each of the cases where the number of repeated transmissions is 1, 3 and 5, the group ID may be notified. In the notification of the relationship between the number of times of repeated transmission (gain) and the preamble ID, for example, when the number of times of repeated transmission is specified by the field in the notification, it is not necessary to explicitly notify information on the number of times of repeated transmission. For example, when the W bit from the beginning of the notification corresponds to the preamble ID in the case where the number of repeated transmissions is one, the preamble ID acquisition unit 304 only reads the W bits from the beginning of the received notification, and the number of repeated transmissions is 1 It is possible to obtain the preamble ID in the case of. Also, if the W + 1th to 2Wth bits of the notification correspond to the number of repeated transmissions of 3 times, the preamble ID acquisition unit 304 reads the W + 1th to 2Wth bits of the notification to make the number of repeated transmissions smaller. You can get the preamble ID for 3 times. According to this, it is not necessary to transmit information on the number of times of transmission repeatedly, so the amount of information related to the notification can be reduced. Note that the same notification can be configured even when the number of times of repeated transmission is set to another value related to gain.

  The transmitting unit 301 identifies and transmits one of the preambles corresponding to the plurality of preamble IDs acquired by the preamble ID acquiring unit 304 according to the amount of resources determined or specified by the used resource amount determining unit 303. . For example, when the correspondence in FIG. 5C is used, the transmitter 301 determines that the number of times of repeated transmission at the time of transmitting to the radio control station 102 is determined to be three. The preamble corresponding to the ID: B is transmitted three times as one unit. In addition, when the use resource amount determination unit 303 determines that the number of times of repeated transmission at the time of transmission to the radio control station 102 is 5 times, the transmission unit 301 determines that the preamble corresponding to the preamble ID: C is 5 times. Send as a unit. Here, the preamble of the random access channel is usually retransmitted while being increased in transmission power until it is received by the receiving device. However, the situation where repeated transmission is required is a situation where the signal can only reach a level that can not be demodulated by only once reaching the receiving device. Therefore, as shown in FIGS. 5A and 5B, the transmitting unit 301 sets the number of times of repeatedly transmitting the same preamble determined by the used resource amount determining unit 303 as one unit, and performs multiple times with the same power. It can be resent. That is, when the used resource amount determining unit 303 repeatedly determines that the number of transmissions is three, the transmitting unit 301 repeatedly transmits the preamble corresponding to the preamble ID: C three times also at the time of retransmission. In this case, the transmitting unit 301 transmits the same signal a total of six times by performing the first transmission and the first retransmission.

  In addition, the transmission unit 301 may perform the above-described retransmission while increasing transmission power. At this time, the transmission unit 301 can also change the preamble to be transmitted according to the number of retransmissions. For example, as shown in FIGS. 6A and 6C, when the number of times of repeated transmission is three, the transmitting unit 301 transmits a preamble whose preamble ID is BA as initial transmission. Then, the transmitting unit 301 transmits a preamble whose preamble ID is BB at the time of the first retransmission (that is, at the time of the second transmission) when the number of times of repeated transmission is three. Similarly, when the number of repeated transmissions is five, the transmission unit 301 transmits a preamble whose preamble ID is CA at the time of initial transmission, as shown in FIGS. 6 (b) and 6 (c). In the first, second, and third retransmissions, the transmission unit 301 repeatedly transmits the preambles of the preamble IDs CB, CC, and CD five times. In this case, the preamble ID acquisition unit 304 acquires information on the correspondence between the number of times of repeated transmission and the number of times of retransmission, and the preamble ID, to which different preamble IDs correspond to the number of times of retransmission.

  Although FIG. 5 (c) and FIG. 6 (c) specify the preamble ID for the case where the number of repeated transmissions is one, the preamble at the time of the first transmission is the same as the preamble of the conventional random access channel. It may be similar. In addition, while the transmission unit 301 increases the transmission power at the time of retransmission only when the number of times of repeated transmission is one, and when the number of times of repeated transmission is multiple, the maximum transmission is performed both at the time of initial transmission The preamble may be transmitted by power.

  It should be noted that for each gain obtained, such as preamble ID: D for 0 dB gain, preamble ID: E for 5 dB gain, preamble ID: C for 10 dB gain, etc. A preamble ID may be defined. At this time, the transmission unit 301 transmits a preamble using a signal transmission method corresponding to each gain. For example, when a gain of 5 dB is to be obtained, the transmission unit 301 specifies a predetermined number of transmissions of a signal corresponding to a gain of 5 dB, and repeatedly transmits a preamble whose preamble ID is E for the specified number of transmissions. In addition, when a gain of 5 dB is to be obtained, the transmission unit 301 may specify a spreading factor corresponding to a gain of 5 dB, and may spread and transmit a preamble of preamble ID E at that spreading factor.

  When the radio control station 102 succeeds in receiving the preamble, it can specify the amount of resources (the number of repetitions) to be used when the terminal 101 transmits a signal to the radio control station 102 according to the preamble ID at that time. . At this time, the radio control station 102 can notify the terminal 101 of the specified amount of resources through, for example, a control signal. The notification of the amount of resources may be a notification by the preamble ID, that is, a notification of the identified preamble ID. When the radio control station 102 succeeds in receiving preambles of a plurality of preamble IDs, the radio control station 102 may select the smallest of the amounts of resources corresponding to the preamble IDs. As a result, when the terminal 101 transmits a signal to the radio control station 102, it is possible to use an unnecessary amount of resources which are necessary for successful reception and are not unnecessarily large.

  The transmitting unit 301 specifies and transmits a preamble similar to the above-described method also when notifying the radio control station 102 of the number of times of repeated transmission (gain) required for signal transmission from the radio control station 102 to the terminal 101. It can be performed. That is, the use resource amount determination unit 303 specifies how many times the signal transmission has been required to demodulate the signal transmitted from the radio control station 102 (acquisition of data included in the signal), and the transmission unit 301 One preamble can be specified and transmitted according to the number of times. For example, when the number of receptions required to demodulate a signal is one, the transmission unit 301 transmits a preamble whose preamble ID is X, and when the number of receptions required to demodulate a signal is two, the preamble ID It is possible to send Y's preamble. According to this, the radio control station 102 needs to know how much gain for coverage extension is required to be obtained when transmitting a signal to the terminal 101, depending on which preamble has been received. it can. Therefore, the radio control station 102 can prevent waste of resources while using an amount of resources that can communicate, by repeatedly transmitting signals for the minimum number of successful receptions of the terminal 101. .

(Configuration of radio control station)
FIG. 4 is a diagram showing an example of a functional configuration of the radio control station 102. As shown in FIG. The radio control station 102 has, for example, a transmitting unit 401, a receiving unit 402, a used resource amount specifying unit 403, a used resource amount notifying unit 404, and a preamble ID notifying unit 405 as its functional configuration.

  The transmitting unit 401 is a functional unit for transmitting a signal to the terminal 101 by, for example, repeatedly transmitting the same data signal one or more times. In addition, when the terminal 101 exists in the coverage area of the radio control station 102, the transmitting unit 401 normally transmits the data signal once, and the terminal 101 does not exist in the coverage area of the radio control station 102, If coverage extension is required, the data signal is transmitted multiple times.

  The receiving unit 402 is a functional unit that receives, for example, a data signal or a preamble transmitted one or more times from the terminal 101, and acquires the content of the data or the preamble ID. In addition, when the terminal 101 exists in the coverage area of the radio control station 102, the receiving unit 402 can usually acquire data included in the signal by receiving the data signal only once. On the other hand, when the terminal 101 does not exist in the coverage area of the radio control station 102 and coverage extension is required, the receiving unit 402 can acquire data by receiving the data signal multiple times.

  The used resource amount specifying unit 403 specifies the amount of the resource to be used (the number of times of repeated transmission) according to which preamble ID the preamble transmitted by the terminal 101 as described above corresponds to. For example, in the examples of FIGS. 5A to 5C, when the radio control station 102 succeeds in receiving the signal whose preamble ID is B, the use resource amount specifying unit 403 transmits a signal from the terminal 101 to the radio control station 102. It specifies that three repetitions of signal transmission should be performed in transmission. At this time, the radio control station 102 can also obtain the required number of repeated transmissions by specifying the number of times the preamble has been detected before successfully receiving the preamble from the terminal. On the other hand, if a preamble specified according to the number of times of repeated transmission is used, even if the radio control station 102 may not detect one or more of the repeatedly transmitted preambles, the radio control station 102 may It is possible to specify the limit number of repeated transmissions. That is, for example, when the terminal 101 repeatedly transmits the preamble three times, the radio control station 102 detects the preamble twice, and as a result, it is assumed that the preamble has been identified. In this case, if the preamble does not correspond to the number of repeated transmissions, the radio control station 102 determines that the number of repeated transmissions is two, but if the number of repeated transmissions is notified by the preamble ID The number of times of repeated transmission can be determined to be three. The used resource amount specifying unit 403 specifies, for example, a gain to be obtained from the preamble ID, and inputs the specified gain to the used resource amount notification unit 404.

  Further, the used resource amount specifying unit 403 is used when the radio control station 102 transmits a signal to the terminal 101 according to which preamble ID the preamble transmitted by the terminal 101 as described above corresponds to. It can also identify the amount of resources that should be. The used resource amount specifying unit 403 may specify, for example, the gain to be obtained from the preamble ID, and may instruct the transmitting unit 401 to use a communication method capable of obtaining the gain. .

  The used resource amount notification unit 404 notifies the terminal 101 via the transmission unit 401 of the amount of resources required for the terminal 101 to transmit a signal to the radio control station 102 specified by the used resource amount specification unit 403. . This notification may be performed, for example, using the resources of the amount required for the radio control station 102 to transmit a signal to the terminal 101 specified by the used resource amount specifying unit 403. The preamble ID notification unit 405 notifies the terminal 101 of the preamble ID for each amount of resources to be used via the transmission unit 401. This notification is the one described in the description of the preamble ID acquisition unit 304 in the terminal 101, and thus the detailed description will be omitted.

(Flow of processing)
Subsequently, some examples of the flow of resource amount specification processing performed between the terminal 101 and the radio control station 102 as described above will be described.

Processing Example 1
In this processing example, the amount of resources to be used in uplink (link for transmitting a signal from the terminal 101 to the radio control station 102) is specified. This process will be described with reference to FIG. In the present processing example, first, the radio control station 102 notifies the terminal 101 of the initial access parameter (S701). Here, the initial access parameter may include, for example, information indicating the correspondence between the above-described number of repeated transmissions (or the amount of resources used or the gain to be obtained) and the preamble ID. Also, the initial access parameter may include at least one of a parameter related to an initial transmission power of the preamble and the number of retransmission attempts.

  Subsequently, the terminal 101 uniquely determines the number of times of repeated transmission of the signal (S702), identifies the preamble of the preamble ID corresponding to that number (S703), and repeats the identified preamble the number of times determined in S702. Send (S704). The terminal 101 may, for example, attempt to transmit a preamble on a conventional random access channel without first transmitting the signal repeatedly. Then, when the preamble is received in the radio control station 102, the radio control station 102 notifies the terminal 101 that repetitive transmission is unnecessary (S708). In this case, the terminal 101 does not repeatedly transmit in the subsequent communication.

  On the other hand, when the radio control station 102 does not repeat transmission and does not succeed in reception of the preamble, the terminal 101 increases the number of times of transmission repeatedly (S705), and tries extension of coverage. Then, the terminal 101 specifies the preamble to be used in response to changing the number of times of repeated transmission (S706), and repeatedly transmits the specified preamble the number of times determined in S705 (S707).

  If the terminal 101 does not receive the notification in S708 even if the number of retransmission attempts of the preamble reaches the value notified by the initial parameter in S704, the radio control station 102 does not repeatedly transmit and receive the preamble. Can not be successful. Note that retransmission of the preamble may be performed with constant power as shown in, for example, FIGS. 5 (a) and 5 (b), or power may be gradually increased as shown in FIGS. 6 (a) and 6 (b). While it may be done. Also, as shown in FIG. 6 (c), different preambles may be transmitted according to the number of retransmissions for each repeated transmission unit, or as shown in FIG. 5 (c), the same preamble may be transmitted regardless of the number of retransmissions. It may be done. Although retransmission is performed with constant power as shown in FIGS. 5 (a) and 5 (b), different preambles may be transmitted according to the number of retransmissions for each repeated transmission unit as shown in FIG. 6 (c). Good. When different preambles are transmitted according to the number of retransmissions, the preambles to be transmitted are specified for each retransmission. When the radio control station 102 succeeds in receiving any of the preambles, the radio control station 102 specifies the number of times of repeated transmission (necessary gain) from the preamble ID of the preamble and notifies the terminal 101 (S708).

  The required gain level (coverage extension level) may be divided in advance in a predetermined number of stages, for example. In this case, the terminal 101 and the radio control station 102 correspond to any of the predetermined number of stages. The process of FIG. 7 can be performed to make the determination. For example, if there are four required gain levels of 0 dB, 0 to 5 dB, 5 to 10 dB, and 10 to 20 dB, the terminal 101 obtains gains of 0 dB, 5 dB, 10 dB, and 20 dB at each level. Use a signal transmission method that can Note that as this signal transmission method, as described above, any method may be used as long as gain can be obtained, for example, by adjustment of the number of repetitions, adjustment of the spreading factor, or the like. Good. Also, in this case, the radio control station 102 notifies the terminal 101 of the preamble ID corresponding to each of the four stages, and the terminal 101 transmits the preamble corresponding to the higher gain level from the lower gain level, for example. And transmit to the radio control station 102 in order. Thereby, the radio control station 102 can grasp how much coverage extension is required.

Processing Example 2
In this processing example, the amount of resources to be used in the downlink (link for transmitting a signal from the radio control station 102 to the terminal 101) is specified. This process will be described with reference to FIG. In the present processing example, first, the radio control station 102 periodically transmits a notification signal (S801). At this time, the terminal 101 determines how many times the reception of the broadcast signal is necessary until it is successfully received, that is, how many times the broadcast signal is detected before the demodulation of the broadcast signal succeeds. Note that this notification signal is an example, and any signal may be used as long as the signal is transmitted a plurality of times.

  Subsequently, the terminal 101 specifies a preamble to be used according to the required number of receptions until the demodulation of the broadcast signal succeeds (S802). Note that the information specifying the preamble used at this time may be notified from the radio control station 102 to the terminal 101 by the broadcast signal of S801. Then, the terminal 101 transmits the preamble identified in S802 to the radio control station 102 (S803). At this time, for example, the terminal 101 may transmit a preamble for the number of times of repetitive transmission in the uplink specified by the processing of FIG. 7, or until the acknowledgment is received from the radio control station 102. You may repeat. Note that the preamble transmitted at this time may be associated with the required number of receptions itself, or may be associated with a gain obtained according to the specified number of receptions. For example, the required gain level (coverage extension level) may be divided in advance in, for example, a predetermined number of stages. In this case, the terminal 101 determines to which of the predetermined number of stages the number of receptions corresponds. Can be determined. For example, if there are four required gain levels of 0 dB, 0 to 5 dB, 5 to 10 dB, and 10 to 20 dB, the terminal 101 determines whether the required number of receptions falls in any of these steps. A determination may be made and a preamble corresponding to the determination may be transmitted. According to this, the types of preambles can be limited to four types, and the number of preambles to be prepared can be suppressed.

Processing Example 3
In this processing example, the amount of resources to be used is specified in both uplink and downlink. This process will be described with reference to FIG. In this processing example, as in processing example 2, first, the radio control station 102 periodically transmits a notification signal (S901). At this time, similarly to the processing example 2, the terminal 101 also determines how many receptions were required before the reception of the broadcast signal succeeded, and how many times the broadcast signal was detected. After that, the terminal 101 determines the number of times to repeatedly transmit the preamble to the radio control station 102, for example, independently (S902). Note that the initial value of the number of times may be notified by, for example, the radio control station 102, or may be determined in accordance with the required number of times of reception specified in S901. After that, the terminal 101 identifies the preamble to be transmitted from the required number of receptions specified in S901 and the number of preamble transmissions determined in S902 (S903), and repeatedly transmits the preamble for the determined number of transmissions (S904). ). The preamble specified here corresponds to the number of times the broadcast signal is detected and the number of times the preamble is repeatedly transmitted.

  FIG. 10A shows an example of the correspondence between the preamble ID used at this time and the number of times of transmission and the number of times of reception described above. As shown in FIG. 10A, for example, in the case where the number of receptions required for successful reception of the signal transmitted by the radio control station 102 is one and the preamble is not repeatedly transmitted (when the number of transmissions is one), The terminal 101 transmits a preamble of preamble ID: AX. Similarly, if the number of receptions required for successful reception of the signal transmitted by the radio control station 102 is three and the preamble is repeatedly transmitted five times, the terminal 101 transmits a preamble of preamble ID: CZ. As the preamble, as shown in FIGS. 6A to 6C, a different preamble ID may be used for each retransmission in which repeated transmission is one unit. In this case, as shown in FIG. 10B, for example, one preamble ID can be identified corresponding to the number of times of repeated transmission, the number of times of repeated reception, and the number of times of retransmission. For example, if the number of receptions required for successful reception of a signal is 2, and the number of repeated transmissions is 5, the terminal 101 transmits a preamble of preamble ID: CAY at the first transmission, and at the first retransmission, the preamble ID: Send a CBY preamble.

  If, for example, the radio control station 102 is not notified of the number of repeated transmissions to be used for communication from the radio control station 102 despite the fact that the terminal 101 has transmitted the preamble in S904, it is assumed that the radio control station 102 has not successfully received the preamble. It can be determined. In this case, the terminal 101 changes the number of repeated transmissions of the preamble and tries to transmit the preamble again. Specifically, the terminal 101 first determines the number of repeated transmissions again (S905). At this time, the number of repeated transmissions determined again may be determined as, for example, a number larger than the number of repeated transmissions determined in S902. Thereafter, since the preamble ID to be transmitted changes as a result of increasing the number of times of repeated transmission, the preamble ID after changing the number of times of repeated transmission is specified (S 906), and the preamble of the specified preamble ID is transmitted (S S 907). After that, the terminal 101 repeatedly receives the notification of the number of transmissions from the radio control station 102 (S 908). Note that the radio control station 102 is notified of the notification of S908 because the radio control station 102 is notified of the number of repetitions of transmission (the number of repetitions of reception for the terminal 101) to be used in the downlink direction by the preamble of S907. The number of transmissions can be repeatedly transmitted. Then, the terminal 101 can know the appropriate number of repeated transmissions in uplink by the notification of S908.

  In addition, when using correspondence as shown in FIG.10 (b), the terminal 101 transmits, changing preamble ID for every resending. That is, for example, if there is no response from the radio control station 102 (notification of the number of repetitions of transmission) after the initial transmission of the number of repetitions determined in S902, the terminal 101 increases the transmission power and retransmits the preambles. . At this time, the terminal 101 performs retransmission using a preamble of an ID different from that at the time of initial transmission. Then, if the notification from the radio control station 102 is not received even if the number of retransmissions reaches, for example, the number of retransmissions notified as an initial access parameter, the terminal 101 increases the number of repeated transmissions, and uses the initial transmission power. Attempt to send a preamble. Also at this time, since the number of times of repeated transmission of the preambles changes, the preamble to be transmitted also changes. Thereafter, the terminal 101 similarly repeats the same processing until a response from the radio control station 102 is received.

  As described above, by specifying the preamble transmitted from the terminal 101, the radio control station 102 can specify the appropriate number of repeated transmissions in both uplink and downlink at one time. Note that, as described in processing examples 1 and 2, the target specified at this time may not be the number of times of repeated transmission, and for example, the coverage extension level may be specified. That is, the radio control station 102 may specify how much coverage extension is required (or how much gain is required) to perform communication with the terminal 101. And, for example, one preamble ID may be allocated for each coverage extension level divided into a predetermined number of stages. In this case, for example, the terminal 101 specifies the coverage extension level without specifying the number of preamble transmissions, identifies the preamble according to the level, and repeats the number of transmissions that can obtain the coverage extension level. The preamble may be sent. Note that techniques other than repetitive transmission (eg, spreading) may be used to obtain a certain coverage extension level.

  In addition, although the above-mentioned method was demonstrated as what notifies a coverage extension level (the number of repetition transmissions) by transmitting a predetermined | prescribed preamble from a terminal to a radio control station, it is not restricted to this. For example, the preamble may be a predetermined signal known between the terminal and the radio control station, and does not have to be a preamble of a random access channel. Also, for example, when the radio control station notifies the terminal of the correspondence between the coverage extension level and the preamble ID, at least a part of the correspondence may be notified, and it is not necessary to notify all at once. May be Thus, it is apparent that the above-described embodiment has been made for the purpose of illustration only, and the invention according to the present disclosure is not limited to the above-described embodiment.

Claims (8)

A communication device for communicating with another communication device,
Specifying means for detecting a signal from the other communication device and specifying an amount of resource used when performing communication of a fixed amount of data from the other communication device to the communication device;
A plurality of predetermined signals known in the communication device and the other communication device, respectively different amounts of resources including at least one of frequency and time used when performing communication of a fixed amount of data Transmitting means for transmitting one predetermined signal corresponding to the amount of resources specified in the specifying means from the plurality of predetermined signals corresponding to the other communication device;
Have
The transmission means specifies the amount of the first resource and the specifying means using the amount of the first resource used when performing communication of a fixed amount of data from the communication device to the other communication device. Identifying one predetermined signal from the plurality of predetermined signals corresponding to the combination with the second resource amount, and transmitting the one predetermined signal to the other communication device;
A communication device characterized by The plurality of predetermined signals include an amount of resources used when performing communication of a certain amount of data from the communication device to the other communication device, and a certain amount of data from the other communication device to the communication device The communication device according to claim 1, corresponding to a combination with the amount of resources used when performing communication. The plurality of predetermined signals known in the communication device and the other communication device correspond to resources including both frequency and time used when performing communication of a fixed amount of data. Or the communication device according to 2. A terminal that communicates with the control station,
Specifying means for detecting a signal from the control station and specifying an amount of resources used when performing communication of a fixed amount of data from the control station to the terminal;
A plurality of predetermined signals known in the terminal and the control station correspond to respectively different amounts of resources including at least one of frequency and time used when performing communication of a fixed amount of data Transmitting means for transmitting to the control station one predetermined signal corresponding to the amount of resources specified in the specifying means from a plurality of predetermined signals;
Have
The transmitting means uses the amount of the first resource used when performing communication of a certain amount of data from the terminal to the control station, and the second amount specified by the first resource and the specifying means. Identifying one predetermined signal from the plurality of predetermined signals corresponding to a combination with the amount of resources of the one and transmitting the one predetermined signal to the control station.
A terminal characterized by A control station that communicates with the terminal,
Specifying means for detecting a signal from the terminal and specifying an amount of resource used when performing communication of a fixed amount of data from the terminal to the control station;
A plurality of predetermined signals known in the control station and the terminal respectively correspond to different amounts of resources including at least one of frequency and time used when performing communication of a fixed amount of data Transmitting means for transmitting to the terminal one predetermined signal corresponding to the amount of resources specified in the specifying means from a plurality of predetermined signals;
Have
The transmission means uses the first resource amount used when performing communication of a fixed amount of data from the control station to the terminal, and the second amount specified by the first resource amount and the identification means. Identifying one predetermined signal corresponding to a combination of the amount of resources and the number of predetermined resources from the plurality of predetermined signals, and transmitting the one predetermined signal to the terminal.
A control station characterized by A communication system comprising a first communication device and a second communication device, the communication system comprising:
The second communication device comprises first communication means for transmitting a signal to the first communication device,
The first communication device is
Specifying means for detecting the signal and specifying an amount of resources used when performing communication of a fixed amount of data from the second communication device to the first communication device;
A plurality of predetermined signals known in the first communication device and the second communication device, respectively, of resources including at least one of frequency and time used when performing communication of a fixed amount of data Second transmitting means for transmitting to the second communication device one predetermined signal corresponding to the amount of resources specified in the specifying means from a plurality of predetermined signals respectively corresponding to different amounts;
Have
The second transmission unit uses the amount of the first resource used when performing communication of a fixed amount of data from the first communication device to the second communication device, and uses the amount of the first resource. One predetermined signal corresponding to the combination of the amount and the amount of the second resource specified by the specifying means is specified from the plurality of predetermined signals, and the one predetermined signal is sent to the second communication device Send,
A communication system characterized by A computer provided in a communication device that communicates with another communication device;
A specifying step of detecting a signal from the other communication device and specifying an amount of resource used when performing communication of a fixed amount of data from the other communication device to the communication device;
A plurality of predetermined signals known in the communication device and the other communication device, respectively different amounts of resources including at least one of frequency and time used when performing communication of a fixed amount of data Transmitting, from the plurality of predetermined signals corresponding thereto, one predetermined signal corresponding to the amount of the resource specified in the specifying step to the other communication device;
A program for executing,
Prior Symbol transmitting step, by using the amount of the first resource used by the communication device when communicating a certain amount of data to the other communication apparatus, in the specifying step to the amount of the first resource And identifying one predetermined signal corresponding to a combination with the identified second resource amount from the plurality of predetermined signals, and transmitting the one predetermined signal to the other communication device.
A program characterized by A control method of a communication device communicating with another communication device, the control method comprising:
A specifying step of detecting a signal from the other communication device and specifying an amount of resource used when performing communication of a fixed amount of data from the other communication device to the communication device;
A plurality of predetermined signals known in the communication device and the other communication device, respectively different amounts of resources including at least one of frequency and time used when performing communication of a fixed amount of data Transmitting, from the plurality of predetermined signals corresponding thereto, one predetermined signal corresponding to the amount of the resource specified in the specifying step to the other communication device;
Have,
Prior Symbol transmitting step, by using the amount of the first resource used by the communication device when communicating a certain amount of data to the other communication apparatus, in the specifying step to the amount of the first resource And identifying one predetermined signal corresponding to a combination with the identified second resource amount from the plurality of predetermined signals, and transmitting the one predetermined signal to the other communication device.
Control method characterized by

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