Wireless terminal and transmission method thereof, and base station and reception method thereof

Abstract

According to the present invention, a wireless frame is transmitted by using HARQ without transmitting header information.　A wireless resource determination unit determines a wireless resource used for transmission, on the basis of information synchronized with a reception device and an identifier of a host wireless terminal. A frame generation unit determines, on the basis of the determined wireless resource, a part of an error correction code of data to be transmitted as a redundancy bit, and generates a wireless frame including the data to be transmitted and the redundancy bit as payloads. A wireless transmission unit transmits the wireless frame to the reception device by using the determined wireless resource.

Description

[Technical field]

[0001] The present technology relates to a wireless system, and more particularly to a wireless system in which a base station receives a wireless frame transmitted from a wireless terminal, and a processing method therein. [Background technology]

[0002] The Internet of Things (IoT) field is expected to create new value by acquiring and analyzing information from various objects. There are various requirements for the wireless technology used to acquire information, but expectations are particularly high for low power consumption and long-distance transmission of wireless terminals. This is because reducing the power consumption of wireless terminals allows them to operate for longer periods of time, or using smaller batteries allows wireless terminals to be made smaller, allowing them to be used for a wider range of applications. Furthermore, long-distance transmission makes it possible to collect information from distant locations, making it possible to obtain information that was previously unavailable.

[0003] As a technology to realize low power consumption of wireless terminals, simplification of communication procedures is being considered. In conventional mobile phones and wireless LANs, wireless terminals receive control signals and signals called beacons periodically transmitted by base stations and access points, transmit connection requests, receive connection permission, and then can transmit data. In this series of procedures, many control signal exchanges are required before data transmission, which consumes a lot of power. Especially in the IoT area, the data transmitted by wireless terminals is mainly small amounts of sensor information of about tens of bytes, such as location information, temperature, and humidity. For this reason, the overhead of control signals for data is large, which is a major issue in realizing low power consumption of wireless terminals. For this reason, a method is being considered in which wireless terminals transmit data without exchanging control information. With this method, wireless terminals can transmit data without receiving control signals, which enables low power consumption of wireless terminals. However, with this method, the base station cannot know in advance what time and frequency the wireless terminal will transmit, so it is necessary to constantly detect and demodulate wireless frames, which requires high functionality of the base station. This causes a problem of high cost of the entire wireless system. Therefore, a wireless system has been devised in which wireless terminals and base stations are both time-synchronized based on a common time using a GPS (Global Positioning System) receiver. In this wireless system, wireless resource rules that determine the time and frequency at which data is transmitted from the transmission cycle, the time obtained from the GPS, and the terminal identifier (ID) are shared in advance between the wireless terminal and base station as a wireless standard. The wireless terminal determines the transmission time and frequency from the transmission cycle, the time obtained from the GPS, and the terminal identifier that are assigned in advance. Meanwhile, the base station similarly determines the time and frequency at which it should receive. This allows the base station to limit the time and frequency at which it will receive in advance, making it possible to realize the system at a low cost.

[0004] Technologies for achieving long-distance transmission include repetitive transmission technology, which repeatedly transmits the same information to improve noise resistance, and error correction technology. Repetitive transmission technology reduces the effects of random noise by waveform-synthesizing the signal received at the base station, thereby improving the signal-to-noise ratio (SNR) of the received signal, thereby achieving long-distance transmission. Error correction technology is a technology that improves the success rate of reception at the receiving end by adding redundant bits to the information to be transmitted using signal processing such as LDPC (Low Density Parity check Code). Therefore, a technology called HARQ (Hybrid Automatic Repeat reQuest), which combines a repeat transmission technology and an error correction technology, is used. In the repeat transmission technology, the S / N ratio improves with the number of repeat transmissions, but it is known that the rate of improvement is a logarithmic function, and the improvement in the S / N ratio saturates even if the number of repeat transmissions is increased. In addition, in the error correction technology, it is possible to improve the S / N ratio by adding more redundant bits, but the amount of information transmitted at one time increases with the number of redundant bits, and the time required for one transmission increases, so the power consumption associated with transmission increases. HARQ is a combination of these technologies and is useful as a method for realizing long-distance transmission. For example, a method of transmitting via a channel using HARQ has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-033541 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned conventional technology using HARQ, it is necessary to add header information to the wireless frame in order to properly rearrange the redundant bits contained in the wireless frame received on the receiving side. Since it is assumed that the header information can be received correctly, it is necessary to improve the noise resistance of the header information, and measures such as extending the transmission time and increasing the power per bit are necessary. In wireless technology for IoT, the information to be transmitted is sensor information, so it is only a few tens of bits, and the proportion of header information is relatively high, which leads to the issue that the transmission time of the wireless frame is long and it becomes inefficient in terms of power consumption.

[0007] This technology was developed in light of these circumstances, and aims to transmit wireless frames using HARQ without transmitting header information. [Means for solving the problem]

[0008] The present technology has been made to solve the above-mentioned problems, and a first aspect thereof is a wireless terminal and a transmission method thereof, comprising: a wireless resource determination unit that determines a wireless resource to be used for transmission based on information synchronized with a receiving device and an identifier of a wireless terminal, a frame generation unit that determines a part of an error correction code of data to be transmitted as a redundant bit based on the determined wireless resource, and generates a wireless frame having the data to be transmitted and the redundant bit as a payload, and a wireless transmission unit that transmits the wireless frame to the receiving device using the determined wireless resource. This brings about an effect of determining a part of an error correction code of data to be transmitted as a redundant bit based on the determined wireless resource, and transmitting a wireless frame including the redundant bit.

[0009] In addition, in the first aspect, the frame generation unit may generate a plurality of wireless frames for the data to be transmitted based on the determined wireless resource using each of a plurality of partial codes obtained by dividing the error correction code as the redundant bits, and the wireless transmission unit may transmit the plurality of wireless frames. This provides an effect of transmitting a wireless frame including each of a plurality of partial codes obtained by dividing the error correction code as redundant bits.

[0010] In addition, in the first aspect, the radio resource determination unit may determine a transmission order of the plurality of partial codes as part of the radio resources. This brings about an effect that the radio terminal determines a transmission order of the plurality of partial codes as part of the radio resources.

[0011] In the first aspect, the radio resource determination unit may determine the transmission order according to a pseudo-random number sequence having information synchronized with the receiving device and the identifier as an initial value, thereby achieving an effect of uniquely determining the transmission order of the plurality of subcodes from the information synchronized with the receiving device and the identifier.

[0012] In the first aspect, the radio resource determination unit may determine the transmission order based on a transmission frequency included in the radio resource, thereby achieving an effect of uniquely determining the transmission order of the plurality of subcodes from the transmission frequency.

[0013] In addition, in this first aspect, the radio resource determination unit may generate synchronization information indicating which of the plurality of partial codes is to be transmitted as the redundant bit, and the radio transmission unit may transmit the synchronization information prior to transmission of the radio frame, thereby providing an effect that a receiving side can uniquely determine a transmission order of the plurality of partial codes from the synchronization information.

[0014] A second aspect of the present technology is a base station and a receiving method thereof, the base station including: a radio resource determination unit that determines a radio resource to be used for reception based on information synchronized with a radio terminal and an identifier of the radio terminal, a radio receiving unit that receives a radio frame including reception data and redundant bits from the radio terminal using the determined radio resource, and a frame synthesis unit that determines which of a plurality of partial codes obtained by dividing an error correction code of the reception data is included as the redundant bit based on the determined radio resource, and synthesizes a frame. This provides an effect of determining which of a plurality of partial codes is included as a redundant bit based on the determined radio resource.

[0015] In addition, in the second aspect, the wireless receiving unit may receive a plurality of wireless frames including the received data, and the frame combining unit may rearrange the redundant bits of the plurality of wireless frames based on the determined wireless resource to restore the error correction code, thereby providing an effect of restoring the error correction code based on the determined wireless resource.

[0016] In addition, in the second aspect, the radio resource determination unit may determine which of the plurality of partial codes is included as the redundant bit according to a pseudo-random number sequence having information synchronized with the receiving device and the identifier as an initial value, thereby achieving an effect of uniquely determining a transmission order of the plurality of partial codes from the information synchronized with the receiving device and the identifier.

[0017] In the second aspect, the radio resource determination unit may determine which of the plurality of partial codes is included as the redundant bit based on a reception frequency at which the radio frame is received, thereby achieving an effect of uniquely determining a transmission order of the plurality of partial codes from the reception frequency.

[0018] In addition, in the second aspect, the radio communication device may further include a plurality of frame detection units provided corresponding to a plurality of pieces of synchronization information indicating which of the plurality of partial codes is included as the redundant bit in the radio frame prior to the radio frame received by the radio receiving unit, and detecting a radio frame matching the synchronization information, and the frame synthesis unit may determine which of the plurality of partial codes is included as the redundant bit depending on which of the plurality of frame detection units has detected it. This brings about an effect of uniquely determining the transmission order of the plurality of partial codes from the synchronization information. [Brief description of the drawings]

[0019] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a wireless system according to an embodiment of the present technology. [Diagram 2] 1 is a diagram illustrating an example of a configuration of a wireless terminal 100 according to an embodiment of the present technology. [Diagram 3] 2 is a diagram illustrating an example of a configuration of a base station 200 according to an embodiment of the present technology. [Figure 4] FIG. 1 is a diagram for explaining an overview of HARQ used in an embodiment of the present technology. [Diagram 5] FIG. 2 is a diagram for explaining a transmission time in HARQ used in an embodiment of the present technology. [Figure 6] FIG. 1 is a diagram illustrating an example of a pseudo-random number sequence generator in HARQ used in an embodiment of the present technology. [Figure 7] FIG. 2 is a diagram showing a first example of generation by a pseudo-random number sequence generator in HARQ used in an embodiment of the present technology. [Figure 8] FIG. 11 is a diagram showing an example of determining a grid number in HARQ used in an embodiment of the present technology. [Figure 9] FIG. 11 is a diagram showing a second example of generation by a pseudo-random number sequence generator in HARQ used in an embodiment of the present technology. [Figure 10]FIG. 1 is a diagram showing an example of determining a frequency in HARQ used in an embodiment of the present technology. [Figure 11] FIG. 13 is a diagram showing a third example of generation by a pseudo-random number sequence generator in HARQ used in an embodiment of the present technology. [Figure 12] 1 is a diagram showing an example of determining a pattern of redundant bits in HARQ used in an embodiment of the present technology. FIG. [Figure 13] 2 is a diagram illustrating an example of a field configuration of a radio frame according to an embodiment of the present technology. [Figure 14] 1 is a sequence diagram showing an example of an operation of a wireless system according to an embodiment of the present technology. [Figure 15] 4 is a flowchart showing an example of a processing procedure of a wireless terminal 100 according to the embodiment of the present technology. [Figure 16] 5 is a flowchart showing an example of a processing procedure of a base station 200 according to the embodiment of the present technology. [Figure 17] FIG. 13 is a diagram illustrating an example of a field configuration of a radio frame according to a third embodiment of the present technology. [Figure 18] FIG. 13 is a diagram illustrating an example of a configuration of a base station 200 according to a third embodiment of the present technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, modes for carrying out the present technology (hereinafter, referred to as embodiments) will be described. The description will be made in the following order. 1. First embodiment (example of determining redundant bit pattern using pseudorandom number sequence) 2. Second embodiment (example in which the relationship between transmission frequency and redundant bits is fixed) 3. Third embodiment (example of fixing the relationship between synchronization information and redundant bits)

[0021] <1. First embodiment> [Radio System] FIG. 1 is a diagram showing an example of the overall configuration of a wireless system according to an embodiment of the present technology.

[0022] This wireless system includes a wireless terminal 100 and a base station 200. In this example, it is assumed that the wireless terminal 100 has a function of detecting or acquiring predetermined data, and wirelessly transmits the data as sensor data to the base station 200. Other devices are further connected to the base station 200, and the sensor data is transmitted as appropriate.

[0023] Although one each of the wireless terminal 100 and the base station 200 is shown here, there may be a plurality of them. As will be described later, the wireless terminal 100 is assigned a terminal identifier, and each of them can be identified by the base station 200.

[0024] [Wireless terminal] FIG. 2 is a diagram showing an example of a configuration of the wireless terminal 100 according to the embodiment of the present technology.

[0025] The wireless terminal 100 includes a GPS receiving unit 110, a terminal identifier holding unit 120, a wireless resource determining unit 130, a wireless control unit 140, a wireless transmitting unit 150, a sensor data acquiring unit 160, and a frame generating unit 170.

[0026] The GPS receiving unit 110 receives GPS signals from GPS satellites and obtains time information and position information.

[0027] The terminal identifier holding unit 120 holds the terminal identifier of this wireless terminal 100. The terminal identifier is a unique identifier assigned to this wireless terminal 100 in advance.

[0028] The radio resource determination unit 130 determines the transmission time, the transmission frequency, and the redundant bits to be transmitted based on a radio resource determination rule, which will be described later.

[0029] The sensor data acquisition unit 160 acquires target sensor data. For example, the sensor data acquisition unit 160 may acquire sensor data periodically or periodically (for example, once per second), or may acquire sensor data when a change occurs in the sensor.

[0030] The frame generating unit 170 generates a wireless frame based on the sensor data acquired by the sensor data acquiring unit 160, the terminal identifier held in the terminal identifier holding unit 120, and information on redundant bits, which will be described later.

[0031] The radio control unit 140 controls the radio transmission unit 150 so as to transmit radio frames at the transmission times and at the transmission frequencies determined by the radio resource determination unit 130 .

[0032] The wireless transmitting unit 150 is an RF (Radio Frequency) circuit that converts the wireless frame generated by the frame generating unit 170 into an electromagnetic wave via an antenna and transmits it into space at a specified transmission time and frequency.

[0033] [Base station] FIG. 3 is a diagram showing an example of a configuration of a base station 200 according to an embodiment of the present technology.

[0034] The base station 200 comprises a GPS receiving unit 210, a receiving terminal identifier holding unit 220, a radio resource determining unit 230, a radio control unit 240, a radio receiving unit 250, a frame detecting unit 260, a frame synthesizing unit 270, a frame demodulating unit 280, and a data acquiring unit 290.

[0035] The GPS receiving unit 210 receives GPS signals from GPS satellites and acquires time information and position information.

[0036] The receiving terminal identifier holding unit 220 holds the terminal identifier of the wireless terminal 100 that is the receiving target. The base station 200 may set the terminal identifier in advance, or may obtain the terminal identifier from another device (e.g., a cloud server, etc.) as necessary.

[0037] The radio resource determination unit 230 determines the reception time, reception frequency, and redundant bits to be included in the received radio frame based on a radio resource determination rule, which will be described later.

[0038] The radio control unit 240 controls the radio receiving unit 250 so as to perform reception at the reception time and at the reception frequency specified by the radio resource determining unit 230 .

[0039] The wireless receiving unit 250 is an RF circuit that converts electromagnetic waves into a received signal via an antenna at a specified receiving time and receiving frequency.

[0040] The frame detection section 260 detects a wireless frame from the signal received by the wireless receiving section 250, using synchronization information, which will be described later.

[0041] The frame synthesis unit 270 synthesizes frames based on information on redundant bits contained in detected and received wireless frames, and reconstructs the frames. Specifically, it synthesizes the waveforms of repeatedly transmitted information, and rearranges the redundant bits to their original order. Details of this process will be described later.

[0042] The frame demodulation section 280 performs a decoding process using error correction.

[0043] The data acquisition unit 290 calculates a CRC (Cyclic Redundancy Check) using the terminal identifier and sensor data of the decrypted data, and judges whether it matches the decrypted CRC. If the CRC matches, it judges that the data has been received normally, and provides the data to a downstream processing block, server, etc.

[0044] [HARQ] FIG. 4 is a diagram for explaining an overview of HARQ used in the embodiment of the present technology.

[0045] As shown in a in the figure, the sensor data transmitted by the wireless terminal 100 forms original data (represented as "D" in the figure) together with the terminal identifier of the wireless terminal 100 (represented as "ID" in the figure), the sensor data, and a CRC calculated using the terminal identifier.

[0046] For the original data, an error correction code is calculated by an error correction technique such as LDPC (Low-Density Parity-Check). As shown in FIG. 1B, in this example, the error correction code of the original data is divided into four and expressed as four redundant bits P1 to P4. That is, this example is an example of a coding rate R=1 / 5. The redundant bits P1 to P4 are an example of a plurality of partial codes described in the claims.

[0047] Here, it is assumed that the radio frame is transmitted four times. As shown in c in the figure, the first radio frame transmits the original data and redundant bit P1. The second radio frame transmits the original data and redundant bit P2. The third radio frame transmits the original data and redundant bit P3. The fourth radio frame transmits the original data and redundant bit P4.

[0048] The base station 200 receives these four radio frames and performs frame synthesis as shown at d in the figure. At this time, waveform synthesis is performed for identical information (i.e., original data) contained in the frames. Then, when all radio frames can be detected as in case #A, the redundant bits P1 to P4 are rearranged to restore the original error correction code. On the other hand, when detection of, for example, the second radio frame fails as in case #B, a zero is inserted into the part corresponding to redundant bit P2.

[0049] After rearrangement in this way, decoding processing is performed using error correction technology, as shown in e in the figure. By checking the CRC, it is possible to determine whether the signal has been received correctly.

[0050] FIG. 5 is a diagram for explaining transmission times in HARQ used in the embodiment of the present technology.

[0051] To utilize HARQ, both wireless terminal 100 and base station 200 are equipped with GPS receivers 110 and 210, and determine wireless resources using time information obtained by each. Here, the transmission time of wireless terminal 100 will be described as one of the wireless resources.

[0052] Time in a wireless system is specified by a superframe (SP), a time slot (TS), and a grid. In this example, one superframe is divided into four time slots. In addition, eight start times are defined as a grid in one time slot.

[0053] First, the current SP number and the start time of that SP number are determined from the GPS time information. The GPS time obtained from the GPS is defined as t. The time obtained from the GPS time is based on January 6, 1980, 00:00:00. Here, the unit of time is seconds. The length of the SP interval is defined as SP_duration. The length of the SP interval is determined in advance as a wireless system. In this case, the SP number is defined as n, and the SP start time of number n is defined as SP(n). start-time Then, it can be determined as follows: Note that the operator div() represents the quotient of the division. n = div(t,SP duration ) SP(n) start-time = n × SP duration

[0054] For example, SP duration = 20 seconds, GPS time = 105 seconds, n = 5, SP(5) start-time =100 seconds.

[0055] Next, the SP number that the wireless terminal 100 can transmit with is determined. This is determined using a transmission period (Period) and a terminal identifier (ID) that are assigned in advance. Since the terminal ID is used for the determination, a different SP number is assigned to each wireless terminal even if they have the same transmission period.

[0056] The transmission period (seconds) is converted to the interval (m) of the SP number using the following formula. m = div(Period,SP duration )

[0057] Next, in order to change the SP number for each wireless terminal, an offset value m oft Calculate the remainder of the division. m oft =mod(ID,m) In this way, the SP number (n) that the wireless terminal 100 can transmit from is determined. mod(n+m oft ,m)=0 When the SP number (n) satisfies the above formula, the wireless terminal 100 can transmit.

[0058] For example, SP duration = 20 seconds, GPS time = 105 seconds, transmission cycle 3 minutes (180 seconds), ID = 1, m = 9, m oft = 1, and transmission is possible when the SP number is n = 8, 17, 26, .... duration Since the transmission period is 20 seconds, transmission opportunities are allocated at 160 seconds (n=8), 340 seconds (n=17), and 520 seconds (n=26), i.e., every 3 minutes (18 seconds).

[0059] Next, the transmission time within the superframe (SP) number determined as described above is determined. The wireless terminal 100 performs repeated transmission in each time slot. Repeated transmission can increase the success rate of communication by sending the same sensor data multiple times, making it possible to realize long-distance communication. Note that there may be only one time slot within a superframe. In that case, this is an example in which repeated transmission is not performed.

[0060] The start time of each time slot can be determined by the start time of the superframe and the number of time slots in the superframe. If the number of divisions of the time slots in SP(n) is nTS, the start time TS(k) of each TS(k), k=0 to (nTS-1) is start-time in SP(n) is determined as follows: In this example, nTS=4. TS(k) start-time in SP(n) =SP(n) start-time +k×SP duration / nTS

[0061] Within a timeslot, multiple transmission start times called grids are defined. In this example, eight start times are defined, from grid(0) to grid(7). The grid in which each wireless terminal transmits is determined by a pseudorandom number sequence.

[0062] FIG. 6 is a diagram showing an example of a pseudo-random number sequence generator in HARQ used in the embodiment of the present technology.

[0063] This is one of the common PN sequence (Pseudorandom Numbers) generators. First, an initial value is set. The initial value refers to a bit of 0 or 1 that is set as the initial value of the delay element shown in the square box in the diagram. In this example, it is composed of 24 delay elements from 1 to 24, so an initial value of 24 bits is set. This type of pseudorandom number sequence generator has the characteristic that the pseudorandom number sequence generated will be different if the initial value is different.

[0064] After setting the initial value, one bit of output is output by moving the generator clock by one. In other words, the value set in delay element 1 in the diagram is output. At the same time, the output is provided to the point connected by the line in the diagram. The circle with an x ​​in the diagram indicates an exclusive OR (XOR) logical operation. For example, the output is XORed with the output of delay element 2 and stored in delay element 1. The necessary operations are performed in the same manner to update the value of each delay element. By moving the clock sequentially, it is possible to obtain the required length of output bits.

[0065] FIG. 7 is a diagram showing a first example of generation by a pseudo-random number sequence generator in HARQ used in an embodiment of the present technology.

[0066] In order to determine the grid in which the wireless terminal 100 will perform transmission, the terminal ID and SP number are set as the initial values ​​of the pseudo-random number sequence, and a 12-bit pseudo-random number sequence is generated. In this example, a total of 24 bits are set as the initial value: 16 bits of the ID and 8 bits of the remainder when the SP number n is divided by 256. After that, the clock is run 12 times to generate a 12-bit pseudo-random number sequence.

[0067] FIG. 8 is a diagram showing an example of how grid numbers are determined in HARQ used in an embodiment of the present technology.

[0068] The grid number for each time slot is determined from the 12 bits obtained by the above process. The 12 bits are divided into four groups of 3 bits each, and each 3-bit group is converted to a decimal number to determine the grid number to be transmitted in each time slot.

[0069] In this example, since the pseudo-random number sequence has 24 delay elements, part of the terminal ID and SP number are used as the initial value, but by using a pseudo-random number sequence with more delay elements, it is possible to use longer terminal IDs and SP numbers as the initial values. Also, since there are four time slots in a superframe and eight grids in a time slot, the grid number was determined from a 12-bit sequence, but even if the number of time slots and the number of grids in a time slot are different, this can be accommodated by generating pseudo-random numbers of the required length.

[0070] FIG. 9 is a diagram illustrating a second generation example of a pseudo-random number sequence generated by a generator in HARQ used in an embodiment of the present technology.

[0071] The number of frequency channels available for use in a wireless system is nF. Here, we will explain using nF = 4. In this example, four transmissions are performed within a superframe, so we will show an example of determining the transmission frequencies to be used for those four transmissions.

[0072] After the 12 bits generated to determine the transmission time mentioned above, an additional 8-bit pseudorandom sequence is generated. The newly generated pseudorandom sequence is 13 to 20.

[0073] FIG. 10 is a diagram showing an example of determining a frequency in HARQ used in an embodiment of the present technology.

[0074] The method for determining the frequency to be used for transmission in each time slot from the 8 bits obtained by the above process is as follows. Since nF=4, it is divided into 4 parts of 2 bits each, and the value obtained by converting each 2 bits into a decimal number is used as the frequency number (0 to 3) to be transmitted. Each frequency number corresponds to the center frequency of the carrier frequency when actually transmitting.

[0075] In this example, the number of available frequencies is four (nF=4), and since there are four TSs, each with two bits, the four groups are determined from a total of eight bits. However, these can be extended by generating a pseudorandom sequence of the required length depending on the number of available frequencies and time slots.

[0076] FIG. 11 is a diagram illustrating a third generation example of a pseudo-random number sequence generator in HARQ used in an embodiment of the present technology.

[0077] In this example, four transmissions are performed within a superframe, so the redundant bits to be transmitted in those four transmissions are determined. As described above, the error correction has a coding rate of R=1 / 5 and there are four types of redundant bits.

[0078] A further 5-bit pseudorandom sequence is generated after the 20 bits used to determine the transmission time and transmission frequency obtained by the above process. The newly generated pseudorandom sequence is 21 to 25. From these 5 bits, the redundant bits to be transmitted in the wireless frame are determined as follows:

[0079] FIG. 12 is a diagram showing an example of determining a pattern of redundant bits in HARQ used in an embodiment of the present technology.

[0080] In this example, it is assumed that redundant bits P1 to P4 are transmitted separately over four radio frames. If the correspondence between the four radio frames and the four redundant bits is classified as a pattern, there are 24 patterns as shown here. In other words, this pattern shows the transmission order of the four redundant bits.

[0081] By using the same pattern between the wireless terminal 100 and the base station 200, the redundant bits P1 to P4 can be correctly rearranged in the base station 200. Since it is inefficient to explicitly transmit this pattern in a header or the like, in this embodiment, the pattern is determined by using a pseudo-random number sequence in each of the wireless terminal 100 and the base station 200.

[0082] The 5-bit PT5 of the pseudo-random number series 21 to 25 described above is converted to a decimal number, and the remainder obtained when dividing it by 24 is determined as the redundant bit pattern. That is, the redundant bit pattern is determined by the following formula. Note that the operator dec() indicates the result of converting the binary bit pattern to a decimal number. pattern=mod(dec(PT5),24)

[0083] This allows the wireless terminal 100 and the base station 200 to independently determine which of P1 to P4 the redundant bit of each wireless frame is, and therefore there is no need to separately transmit which of P1 to P4 the redundant bit is.

[0084] [Radio frame] FIG. 13 is a diagram illustrating an example of a field configuration of a radio frame according to the embodiment of the present technology.

[0085] As described above, the terminal identifier ID, the sensor data, and their CRCs constitute the original data D. From these, redundant bits P1 to P4 are calculated using an error correction technique such as LDPC.

[0086] Each of the radio resource determination units 130 and 230 determines a pattern of redundant bits using the above-mentioned pseudo-random number sequence. This determines which of P1 to P4 the redundant bit is included in the payload of the radio frame. In the example shown in the figure, the redundant bit P2 is included in the payload.

[0087] When the wireless terminal 100 transmits a wireless frame, it transmits synchronization information Sync prior to the payload. This synchronization information Sync is known information for frame detection. The base station 200 detects the wireless frame by detecting a signal that matches the synchronization information Sync.

[0088] However, it is not necessary to explicitly transmit which of P1 to P4 the redundant bit is, since it can be determined independently in each of the wireless terminal 100 and the base station 200. Therefore, when the frame length is fixed, it is possible to omit the header information as in this example.

[0089] [Operation] FIG. 14 is a sequence diagram showing an example of operation of the wireless system according to the embodiment of the present technology.

[0090] After acquiring sensor data (811), the wireless terminal 100 determines wireless resources (812). At this time, GPS reception is performed, and the information and the terminal identifier are used to determine the transmission time, transmission frequency, and redundant bits to be transmitted in each wireless frame. Repeated transmission is performed based on the determined wireless resources (813 to 816).

[0091] The base station 200 periodically performs GPS reception and calculates the reception time, reception frequency, and information on redundant bits included in the wireless frame using the terminal identifier to be received (821). The wireless frame is received based on the calculated reception time and reception frequency (822 to 825). Then, the base station 200 performs frame synthesis on the wireless frames (826) and acquires the reception data (827).

[0092] FIG. 15 is a flowchart showing an example of a processing procedure of the wireless terminal 100 according to the embodiment of the present technology.

[0093] The sensor data acquisition unit 160 acquires sensor data periodically or periodically, or when a change occurs in the sensor (step S911). When the sensor data is acquired (step S911: Yes), the GPS receiver 110 receives a GPS signal and acquires time information (step S912).

[0094] The radio resource determination unit 130 determines the transmission time, transmission frequency, and redundant bits to be transmitted for the radio frames to be transmitted (for example, four frames) from the acquired time information and terminal identifier (step S913), and sets the count value for counting the radio frame number to "1" (step S914).

[0095] The frame generation unit 170 generates a radio frame based on the radio frame number and the parameters determined in the radio resource determination (step S915). The radio transmission unit 150 transmits the radio frame based on the radio frame number and the parameters determined in the radio resource determination (step S916).

[0096] It is checked whether the number of transmissions of wireless frames has reached an upper limit (e.g., four frames) (step S917). If the number of transmissions has reached the upper limit (step S917: Yes), the transmission process ends. On the other hand, if the number of transmissions is equal to or less than the upper limit (step S917: No), the count value of the wireless frame number is incremented (step S918), and the next wireless frame is generated (step S915).

[0097] FIG. 16 is a flowchart showing an example of a processing procedure of the base station 200 according to the embodiment of the present technology.

[0098] The GPS receiver 210 periodically receives a GPS signal and acquires time information (step S921).

[0099] The wireless resource determination unit 230 uses the terminal identifier of the receiving target and the GPS reception information to determine the reception time, reception frequency, and information on the redundant bits included in the received wireless frame (step S922), and sets the count value for counting the wireless frame number to "1" (step S923).

[0100] The wireless receiving unit 250 performs a receiving operation based on the wireless frame number and the parameters determined in the wireless resource determination (step S924).

[0101] The frame detection unit 260 detects a frame using the synchronization information Sync, which is known information (step S925). If the frame is detected (step S925: Yes), the frame synthesis unit 270 synthesizes radio frames based on the radio frame number and the parameters determined in the radio resource determination (step S926). Specifically, this involves synthesizing waveforms of identical information and rearranging redundant bits. If the frame is not detected (step S925: No), frame synthesis is not performed and the corresponding redundant bits are treated as zero.

[0102] It is checked whether the number of transmissions of the wireless frame has reached the upper limit (step S927). If the number of transmissions has reached the upper limit (step S927: Yes), the frame demodulation unit 280 performs a decoding process on the combined wireless frame using an error correction technique (step S931). Then, the data acquisition unit 290 uses the decoding result to determine whether the data has been correctly received using CRC (step S932).

[0103] On the other hand, if the number of transmissions has not reached the upper limit (step S927: No), the count value of the wireless frame number is incremented (step S928), and the next receiving operation is performed (step S924).

[0104] In this way, according to the first embodiment of the present technology, the pattern of redundant bits is determined by a pseudo-random number sequence in each of the wireless terminal 100 and the base station 200, so that HARQ can be used without explicitly transmitting information regarding the redundant bits. In this case, the header information can be omitted, so that the power consumption in the wireless terminal 100 can be suppressed, and long-distance transmission can be performed while reducing the transmission power of the wireless terminal 100.

[0105] <2. Second embodiment> In the first embodiment described above, the redundant bit pattern is determined by a pseudo-random number sequence in each of the wireless terminal 100 and the base station 200, but in this second embodiment, the redundant bit pattern is determined from the transmission frequency. Note that the configuration itself as a wireless system is the same as that of the first embodiment described above, so a detailed description will be omitted.

[0106] As described above, the transmission frequency is determined in the radio resource determination units 130 and 230. The determined frequency is denoted as f. Also, it is assumed that there are four types of redundant bits that can be transmitted, P1 to P4, as in the first embodiment. In this case, the redundant bits to be transmitted are determined from the transmission frequency as follows, where P indicates the number of the redundant bit to be transmitted. P = mod(f,4)

[0107] That is, in the second embodiment, the transmission frequency and the redundant bits to be transmitted are determined in association with each other. Therefore, the relationship between the transmission frequency and the redundant bits is fixed, for example, frequency #1 corresponds to redundant bit #1. This makes it possible to omit the process of calculating the redundant bits of the wireless frame in the wireless terminal 100 and the base station 200. In particular, the base station 200 can obtain information on the redundant bits included in the received wireless frame from information on the reception frequency, which makes it possible to reconstruct the wireless frame.

[0108] In this way, according to the second embodiment of the present technology, the process of determining the pattern of redundant bits can be simplified by fixing the relationship between the transmission frequency and the redundant bits.

[0109] <3. Third embodiment> In the above-mentioned first embodiment, the redundant bit pattern is determined by a pseudo-random number sequence in each of the wireless terminal 100 and the base station 200, but in this third embodiment, the redundant bit pattern is determined from synchronization information in the base station 200. Note that the configuration itself as a wireless system is similar to that of the above-mentioned first embodiment, so a detailed description thereof will be omitted.

[0110] In the third embodiment, the wireless terminal 100 determines the transmission redundant bits in the same manner as in the first embodiment. The payload of the wireless frame is also formed in the same manner as in the first embodiment. However, as described below, the wireless terminal 100 transmits synchronization information corresponding to the redundant bits prior to the payload.

[0111] [Radio frame] FIG. 17 is a diagram illustrating an example of a field configuration of a wireless frame according to the third embodiment of the present technology.

[0112] The payload portion of the radio frame in the third embodiment is similar to that in the first embodiment, and also similar in that synchronization information is transmitted prior to the payload and that header information is not transmitted.

[0113] In the figure, "a" indicates a case where redundant bit P2 is transmitted, and a unique known sequence called Sync2 is used as the synchronization information used for frame detection. Also, "b" indicates a case where redundant bit P3 is transmitted, and a unique known sequence called Sync3 is used as the synchronization information used for frame detection. Similarly, unique known sequences (Sync1, Sync4) are used for redundant bits P1 and P4. This makes it possible to link the type of redundant bit included in the wireless frame with the known sequence of synchronization information.

[0114] [Base station] FIG. 18 is a diagram showing an example of a configuration of a base station 200 according to the third embodiment of the present technology.

[0115] The configuration of the base station 200 in the third embodiment is basically the same as that in the first embodiment described above, except that frame detection units 261 to 264 are provided to individually detect the unique known series (Sync1 to Sync4).

[0116] The frame synthesis unit 270 performs the synthesis based on which of the frame detection units 261 to 264 detected the frame, that is, based on which known sequence the synchronization information of the received wireless frame is. This makes it possible for the base station 200 to omit the process of calculating redundant bits of the wireless frame.

[0117] In this way, according to the third embodiment of the present technology, the process of determining the pattern of redundant bits in base station 200 can be simplified by fixing the relationship between synchronization information and redundant bits.

[0118] The above-mentioned embodiment shows an example for realizing the present technology, and the matters in the embodiment and the matters specified in the claims correspond to each other. Similarly, the matters specified in the claims and the matters in the embodiment of the present technology having the same name correspond to each other. However, the present technology is not limited to the embodiment, and can be realized by applying various modifications to the embodiment within the scope of the gist of the technology.

[0119] The processing procedures described in the above embodiments may be regarded as a method having a series of these procedures, or as a program for causing a computer to execute the series of procedures or a recording medium for storing the program. For example, a CD (Compact Disc), an MD (MiniDisc), a DVD (Digital Versatile Disc), a memory card, a Blu-ray (registered trademark) Disc, etc. may be used as this recording medium.

[0120] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0121] The present technology can also be configured as follows. (1) a radio resource determination unit that determines radio resources to be used for transmission based on information synchronized with a receiving device and an identifier of a wireless terminal; a frame generating unit that determines a part of an error correction code of data to be transmitted as a redundant bit based on the determined wireless resource and generates a wireless frame having the data to be transmitted and the redundant bit as a payload; a wireless transmission unit that transmits the wireless frame to the receiving device using the determined wireless resource; A wireless terminal comprising: (2) the frame generation unit generates a plurality of radio frames for the data to be transmitted based on the determined radio resource, using each of a plurality of partial codes obtained by dividing the error correction code as the redundant bit; The wireless transmission unit transmits the plurality of wireless frames. A wireless terminal as described in (1) above. (3) The radio resource determination unit determines a transmission order of the plurality of subcodes as part of the radio resource. A wireless terminal as described in (2). (4) The radio resource determination unit determines the transmission order according to information synchronized with the receiving device and a pseudo-random number sequence having the identifier as an initial value. A wireless terminal as described in (3). (5) The radio resource determination unit determines the transmission order based on transmission frequencies included in the radio resources. A wireless terminal as described in (3). (6) the radio resource determination unit generates synchronization information indicating which of the plurality of partial codes is to be transmitted as the redundant bit; The wireless transmission unit transmits the synchronization information prior to transmitting the wireless frame. A wireless terminal as described in (3). (7) a radio resource determination unit that determines radio resources to be used for reception based on information synchronized with a radio terminal and an identifier of the radio terminal; a radio receiving unit that receives a radio frame including received data and redundant bits from the radio terminal using the determined radio resource; a frame synthesis unit that determines which of a plurality of partial codes obtained by dividing an error correction code of the received data is included as the redundant bit based on the determined wireless resource, and synthesizes a frame; A base station comprising: (8) the wireless receiving unit receives a plurality of wireless frames including the reception data; The frame synthesis unit rearranges the redundant bits of the plurality of radio frames based on the determined radio resource to restore the error correction code. The base station according to (7) above. (9) The radio resource determination unit determines which of the plurality of partial codes is included as the redundant bit according to information synchronized with the receiving device and a pseudorandom number sequence having the identifier as an initial value. The base station according to (8). (10) The radio resource determination unit determines which of the plurality of partial codes is included as the redundant bit based on a reception frequency at which the radio frame is received. The base station according to (8). (11) The wireless communication method further includes a plurality of frame detection units provided corresponding to a plurality of pieces of synchronization information indicating which of the plurality of partial codes is included as the redundant bit in the wireless frame prior to the wireless frame received by the wireless receiving unit, and detecting a wireless frame matching the synchronization information, The frame synthesis unit determines which of the plurality of partial codes is included as the redundant bit depending on which of the plurality of frame detection units has detected the redundant bit. The base station according to (8). (12) A radio resource determination unit determines radio resources to be used for transmission based on information synchronized with the receiving device and an identifier of the wireless terminal; a frame generation unit determines a part of an error correction code of data to be transmitted as a redundant bit based on the determined wireless resource, and generates a wireless frame having the data to be transmitted and the redundant bit as a payload; A radio transmission unit transmits the radio frame to the receiving device using the determined radio resource. A wireless terminal transmission method. (13) A radio resource determination unit determines radio resources to be used for reception based on information synchronized with the radio terminal and an identifier of the radio terminal; a radio receiving unit receiving a radio frame including received data and redundant bits from the radio terminal using the determined radio resource; A frame synthesis unit determines which of a plurality of partial codes obtained by dividing the error correction code of the received data is included as the redundant bit based on the determined wireless resource, and synthesizes the frame. Base station reception method. [Explanation of symbols]

[0122] 100 Wireless terminal 110 GPS receiver 120 Terminal Identifier Storage Unit 130 Radio Resource Determination Unit 140 Radio control unit 150 Radio transmitter 160 Sensor data acquisition unit 170 Frame Generation Unit 200 base stations 210 GPS receiver 220 Receiving terminal identifier storage unit 230 Radio Resource Determination Unit 240 Radio control unit 250 Radio receiver 260~264 Frame detection section 270 Frame Synthesis Section 280 Frame demodulation section 290 Data Acquisition Section

Claims

1. a radio resource determination unit that determines radio resources to be used for transmission based on information synchronized with the receiving device and an identifier of the wireless terminal; a frame generating unit that determines a part of an error correction code of data to be transmitted as a redundant bit based on the determined wireless resource and generates a wireless frame having the data to be transmitted and the redundant bit as a payload; a wireless transmission unit that transmits the wireless frame to the receiving device using the determined wireless resource; A wireless terminal comprising:

2. the frame generation unit generates a plurality of radio frames for the data to be transmitted based on the determined radio resource, using each of a plurality of partial codes obtained by dividing the error correction code as the redundant bit; The wireless transmission unit transmits the plurality of wireless frames.

2. The wireless terminal of claim 1.

3. The radio resource determination unit determines a transmission order of the plurality of subcodes as part of the radio resource.

3. The wireless terminal of claim 2.

4. The radio resource determination unit determines the transmission order according to information synchronized with the receiving device and a pseudo-random number sequence having the identifier as an initial value.

4. The wireless terminal of claim 3.

5. The radio resource determination unit determines the transmission order based on transmission frequencies included in the radio resources.

4. The wireless terminal of claim 3.

6. the radio resource determination unit generates synchronization information indicating which of the plurality of partial codes is to be transmitted as the redundant bit; The wireless transmission unit transmits the synchronization information prior to transmitting the wireless frame.

4. The wireless terminal of claim 3.

7. a radio resource determination unit that determines radio resources to be used for reception based on information synchronized with a radio terminal and an identifier of the radio terminal; a radio receiving unit that receives a radio frame including received data and redundant bits from the radio terminal using the determined radio resource; a frame synthesis unit that determines which of a plurality of partial codes obtained by dividing an error correction code of the received data is included as the redundant bit based on the determined wireless resource, and synthesizes a frame; A base station comprising:

8. the wireless receiving unit receives a plurality of wireless frames including the reception data; The frame synthesis unit rearranges the redundant bits of the plurality of radio frames based on the determined radio resource to restore the error correction code. The base station according to claim 7.

9. The wireless resource determination unit determines which of the plurality of partial codes is included as the redundant bit according to information synchronized with the wireless terminal and a pseudorandom number sequence having the identifier as an initial value. The base station according to claim 8.

10. The radio resource determination unit determines which of the plurality of partial codes is included as the redundant bit based on a reception frequency at which the radio frame is received. The base station according to claim 8.

11. a plurality of frame detection units each corresponding to a plurality of pieces of synchronization information indicating which of the plurality of partial codes is included as the redundant bit in the radio frame prior to the radio frame received by the radio receiving unit, the frame detection units detecting a radio frame matching the synchronization information; The frame synthesis unit determines which of the plurality of partial codes is included as the redundant bit depending on which of the plurality of frame detection units has detected the redundant bit. The base station according to claim 8.

12. a radio resource determination unit determining radio resources to be used for transmission based on information synchronized with the receiving device and an identifier of the wireless terminal; a frame generation unit determines a part of an error correction code of data to be transmitted as a redundant bit based on the determined wireless resource, and generates a wireless frame having the data to be transmitted and the redundant bit as a payload; A radio transmission unit transmits the radio frame to the receiving device using the determined radio resource. A wireless terminal transmission method.

13. a radio resource determination unit determining radio resources to be used for reception based on information synchronized with the radio terminal and an identifier of the radio terminal; a radio receiving unit receiving a radio frame including received data and redundant bits from the radio terminal using the determined radio resource; A frame synthesis unit determines which of a plurality of partial codes obtained by dividing the error correction code of the received data is included as the redundant bit based on the determined wireless resource, and synthesizes the frame. Base station reception method.

Images