JP2013055473A - Transmitter, receiver, and transmission method and program for spectrum aggregation to which interleaving is applied across different carrier signals - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter, etc. for spectrum aggregation which improves frequency diversity gain by transmitting a transmission signal consisting of transmission bit strings per carrier signal which have been interleaved at random across the carrier signals in different frequency bands to impart correlationship to the transmission bit strings.SOLUTION: A transmitter includes interleave means which interleaves each coded bit string output from channel coding means across carrier signals. The interleave means includes: bit string dividing means of dividing across the carrier signals each coded bit string which is output from the channel coding means on the basis of the number of carrier signals, and also executes this dividing operation from a carrier signal having high priority of radio characteristic values on the basis of priority corresponding to radio characteristic values so that many data bits will be included; and bit string multiplexing means which multiplexes, according to symbol mapping, a plurality of coded bit strings per carrier signal which are output from the bit string dividing means.

Description

  The present invention relates to a transmitter and receiver technology for spectrum aggregation (or carrier aggregation or frequency aggregation).

  In recent years, with the development of wireless communication standards, communication capacity has been increased. In particular, according to IMT-Advanced, the goal is to achieve a transmission rate of 1 Gbps when stationary and several hundred Mbps even when moving. In order to achieve this goal, a frequency bandwidth of about 100 MHz is considered necessary. However, frequency resources are already tight, and it is very difficult to secure a continuous broadband at once.

  In order to solve this problem, there is a spectrum aggregation technique. “Spectrum aggregation” is a technique in which a plurality of carrier signals having frequency bands separated from each other are bundled and transmitted simultaneously. According to this technique, a wide frequency band can be secured by simultaneously using a plurality of carrier signals having different frequency characteristics.

  As a spectrum aggregation system, there is a technique in which carrier signals in a plurality of frequency bands having different propagation characteristics are allocated to users according to the user's QoS (Quality Of Service) (see, for example, Patent Document 1). According to this technology, as the user's QoS, the average transmission rate, delay (average, maximum delay, jitter, etc.), frame error rate, transmission power, maximum transmission rate, and minimum guarantee required for each application started by the user on the terminal Consider transmission speed. Each user can be allocated an optimal frequency band according to QoS, and frequency resources can be efficiently operated.

JP 2006-094001 A

  The above-described prior art is merely based on a frequency band allocation method for each user. Therefore, independent signal processing (for example, error correction code processing, modulation processing, demodulation processing) is executed for each carrier signal in a different frequency band. That is, a plurality of carrier signals having a plurality of frequency bands are not used at the same time, and a transmission bit string does not execute signal processing across carrier signals.

  On the other hand, by using a spectrum aggregation technique, it is generally possible to correlate transmission bit strings transmitted between different carrier signals. As a result, synthesis is possible at the time of demodulation in the receiver, and frequency diversity gain can be obtained effectively. Furthermore, by applying interleaving across different carrier signals, it is conceivable that the transmission bit sequence is correlated to improve the transmission characteristics.

  However, the interleaving technique in the prior art is merely an interleaving of the transmission bit string as much as possible in order to obtain a sufficient frequency diversity gain within the same frequency band. On the other hand, according to the spectrum aggregation system, since different frequency bands are used for each carrier signal, there is a high possibility that sufficient characteristics cannot be obtained unless an interleaving process considering these propagation characteristics is applied.

  Therefore, the present invention provides a frequency diversity gain by correlating the transmission bit string by transmitting a transmission signal in which the transmission bit string for each carrier signal is interleaved between the carrier signals of different frequency bands as randomly as possible. An object of the present invention is to provide a transmitter, a receiver, a method, and a program for spectrum aggregation that can improve performance.

According to the present invention, a transmitter for spectrum aggregation that transmits simultaneously from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other,
Channel coding means for performing error correction coding on a bit string of a transmission block for each carrier signal and outputting a coded bit string including data bits and / or parity bits divided based on the number of resource blocks;
Interleaving means for interleaving each coded bit string output from the channel coding means across the carrier signal;
For each carrier signal, frequency signal processing is performed on the encoded bit string output from the interleaving unit, and the signal is output to each transmitting antenna.
Interleaving means
Wireless characteristic storage means for storing a wireless characteristic value for each carrier signal;
Each coded bit string output from the channel coding means is divided based on the number of carrier signals across the carrier signals, and the priority order of the radio characteristic values is high based on the priority order according to the radio characteristic values. Bit string dividing means for dividing the carrier signal so as to include many data bits;
Bit string multiplexing means for multiplexing a plurality of encoded bit strings for each carrier signal output from the bit string dividing means according to symbol mapping;
It has an execution flag generating means for generating an execution flag including whether or not inter-carrier interleaving is executed to be transmitted to the receiver.

According to another embodiment of the transmitter for spectrum aggregation of the present invention,
Interleaving means
As a radio characteristic value for each carrier signal, a radio quality value, a Doppler frequency, a center frequency and a combination thereof are used.
It is also preferable that the priority order is the order from the carrier signal in which the radio environment is favorable according to the radio characteristic value.

According to another embodiment of the transmitter for spectrum aggregation of the present invention,
When the number of transmittable bits based on the symbol mapping of each carrier signal is the same,
The bit string dividing means divides each encoded bit string equally based on the number of carrier signals,
The bit string multiplexing means preferably multiplexes a plurality of encoded bit strings for each carrier signal output from the bit string dividing means alternately by the number of transmittable bits.

According to another embodiment of the transmitter for spectrum aggregation of the present invention,
When the number of transmittable bits based on the symbol mapping of each carrier signal is different,
The bit string dividing means divides each encoded bit string at a ratio corresponding to the number of transmittable bits of each carrier signal,
It is also preferable that the bit string multiplexing unit alternately multiplexes a plurality of encoded bit strings for each carrier signal output from the bit string dividing unit by the number of transmittable bits according to the number of transmittable bits for each carrier signal. .

According to another embodiment of the transmitter for spectrum aggregation of the present invention,
The bit string multiplexing means of the interleaving means multiplexes the number of bits according to the symbol mapping. QPSK symbol mapping: 2 bits each 16QAM symbol mapping: 4 bits 64 QAM symbol mapping: 6 bits each

According to another embodiment of the transmitter for spectrum aggregation of the present invention,
The bit string dividing means and the bit string multiplexing means are preferably executed only when the difference between the radio characteristic values between the carrier signals is within a predetermined threshold with reference to the radio characteristic storage means.

According to the present invention, it is a receiver that communicates with the transmitter described above, and is a receiver for spectrum aggregation that receives simultaneously from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other,
Frequency signal processing means for performing frequency signal processing on the reception signal output from the receiving antenna for each carrier signal and outputting each encoded bit string, and each encoded bit string output from the frequency signal processing means across the carrier signal Deinterleaving means for deinterleaving,
Channel decoding means for decoding the encoded bit string output from the deinterleaving means for each carrier signal;
Deinterleaving means
The execution flag including the presence / absence of inter-carrier interleaving is received from the transmitter,
Using the execution flag, each encoded bit string output from the frequency signal processing means across the carrier signal is demultiplexed and separated for each carrier signal,
The separated encoded bit strings are combined and restored for each carrier signal.

According to the present invention, for each of a plurality of carrier signals whose frequency bands are separated from each other, a transmission method for spectrum aggregation in a transmitter that simultaneously transmits from a plurality of antennas,
A first step of performing error correction coding on a bit string of a transmission block for each carrier signal and outputting a coded bit string including data bits and / or parity bits, which is partitioned based on the number of resource blocks;
A second step of interleaving each encoded bit string output from the channel encoding means across the carrier signal;
A third step of performing frequency signal processing on the encoded bit string output from the interleaving means for each carrier signal, and outputting to each transmitting antenna;
Have
The second step is
A radio characteristic storage unit that stores a radio characteristic value for each carrier signal fed back from the receiver;
Each coded bit string output from the channel coding means is divided based on the number of carrier signals across the carrier signals, and the priority order of the radio characteristic values is high based on the priority order according to the radio characteristic values. Dividing the carrier signal so as to include many data bits;
A step of multiplexing a plurality of encoded bit sequences for each carrier signal output from the bit sequence dividing means according to symbol mapping;
Generating an execution flag including the presence / absence of inter-carrier interleaving to be transmitted to the receiver.

According to the present invention, for each of a plurality of carrier signals whose frequency bands are separated from each other, a transmission program for causing a computer mounted on a transmitter for spectrum aggregation to transmit simultaneously from a plurality of antennas,
Channel coding means for performing error correction coding on a bit string of a transmission block for each carrier signal and outputting a coded bit string including data bits and / or parity bits divided based on the number of resource blocks;
Interleaving means for interleaving each coded bit string output from the channel coding means across the carrier signal;
For each carrier signal, frequency signal processing is performed on the encoded bit string output from the interleaving unit, and the signal is output to each transmitting antenna.
Interleaving means
Radio characteristic storage means for storing a radio characteristic value for each carrier signal fed back from the receiver;
Each coded bit string output from the channel coding means is divided based on the number of carrier signals across the carrier signals, and the priority order of the radio characteristic values is high based on the priority order according to the radio characteristic values. Bit string dividing means for dividing the carrier signal so as to include many data bits;
Bit string multiplexing means for multiplexing a plurality of encoded bit strings for each carrier signal output from the bit string dividing means according to symbol mapping;
The computer is caused to function as an execution flag generating means for generating an execution flag including whether or not inter-carrier interleaving is performed to be transmitted to the receiver.

  According to the transmitter, receiver, method, and program for spectrum aggregation of the present invention, a transmission signal in which a transmission bit string for each carrier signal is interleaved between carrier signals in different frequency bands as randomly as possible is transmitted. Thus, the transmission bit string can be correlated, and the frequency diversity gain can be improved.

It is a block diagram of the communication system for spectrum aggregation in this invention. It is a functional block diagram of the transmitter for spectrum aggregation in this invention. It is an internal block diagram of the channel encoding part and interleaving part in this invention. It is explanatory drawing showing the process of the buffering part in a channel encoding part. It is explanatory drawing showing the process of the interleaving part in the case of the number of carrier signals 2. It is explanatory drawing showing the process of the interleaving part in the case of the number of carrier signals 3. It is explanatory drawing showing the process of the bit sequence division | segmentation part in case the number of transmission bits of each carrier signal differs. It is explanatory drawing showing the process of the bit sequence division part which selects the bit sequence which contains the most data bits. It is explanatory drawing showing the process of the bit sequence multiplexing part in case the number of transmission bits of each carrier signal differs. It is a functional block diagram of the receiver for spectrum aggregation in this invention. 5 is a graph showing average SNR vs. bit error rate (BER) characteristics.

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

  FIG. 1 is a configuration diagram of a communication system for spectrum aggregation according to the present invention.

  According to FIG. 1, the transmitter 1 in the present invention employs an OFDM (Orthogonal Frequency Division Multiplexing) transmission system. The transmitter 1 is for spectrum aggregation, and simultaneously transmits a plurality of carrier signals having frequency bands separated from each other from a plurality of transmission antennas.

  The transmitter 1 transmits transmission signals based on different first and second transmission block (TB) bit strings from the first and second transmission antennas to different carrier signals (for example, an 800 MHz band carrier and a 2 GHz band). Simultaneously transmitted by a combination of carriers). The transmission signal transmitted from the transmitter 1 passes through different channels (characteristics (for example, response characteristics, channel state information CSI (channel state information) is represented by a channel matrix h) for each carrier signal, Receives noise (its characteristic is represented by a noise matrix n).

  On the other hand, the receiver 2 can communicate with the transmitter 1 and realizes spectrum aggregation by simultaneously receiving signals from a plurality of carriers whose frequency bands are separated from each other from a plurality of receiving antennas. The receiver 2 restores the first and second transmission block bit strings from the reception signals received by the first and second reception antennas.

  Here, in the MIMO (Multiple Input Multiple Output) communication method in the prior art, a plurality of transmission bit strings are transmitted in the same frequency band. On the other hand, in the spectrum aggregation communication system of the present invention, a plurality of transmission bit strings are transmitted in different frequency bands. In that respect, they are different.

  Therefore, according to FIG. 1, the first transmission signal transmitted from the first transmission antenna of the transmitter 1 is received as a reception signal only by the first reception antenna of the receiver 2. Similarly, the second transmission signal transmitted from the second transmission antenna of the transmitter 1 is received as a reception signal only by the second reception antenna of the receiver 2. Therefore, according to the present invention, unlike the MIMO scheme, one transmission signal transmitted from each transmission antenna of the transmitter 1 is not received simultaneously by all the reception antennas of the receiver 2.

  In FIG. 1, the frequency band of the first transmission signal is 800 MHz, and the frequency band of the second transmission signal is 2 GHz. Of course, the available frequency band is not limited to this.

  FIG. 2 is a functional configuration diagram of a transmitter for spectrum aggregation in the present invention.

  According to FIG. 2, the transmitter 1 includes a data transmission unit 10, first and second channel encoding units 111 and 112, an interleaving unit 12, and first and second frequency signal processing units 131 and 132. And first and second transmission antennas 141 and 142. These functional components excluding the transmitting antenna are realized by causing a processor (for example, DSP (Digital Signal Processor) or FPGA (Field Programmable Gate Array)) installed in the transmitter to execute a predetermined program using a memory. Is done. In the following description, it is assumed that the transmitter 1 is also applied to, for example, an LTE (Long-Term Evolution) -Advanced base station.

  Channel encoders 111 and 112 and frequency signal processors 131 and 132 are provided for each carrier signal (CC (Component Carrier)). On the other hand, only the interleave unit 12 is provided in common across a plurality of carrier signals. The present invention is characterized in that two transmission bit strings are interleaved across a plurality of carrier signals. That is, each of the two transmission signals includes component information of the transmission block bit sequence and component information in the transmission block bit sequence.

[Channel coding section]
Channel coding sections 111 and 112 perform error correction coding on a bit string of a transmission block for each carrier signal, and output a coded bit string including data bits and / or parity bits, which is divided based on the number of resource blocks. .

  FIG. 3 shows functional components of the channel coding unit and interleaving unit in the present invention.

  According to FIG. 3, channel coding sections 111 and 112 have a coding section, a sub-block interleaver, and a buffering section.

The encoding unit inputs a transmission block bit string (TB (Transport Block)) transmitted independently for each carrier signal. The encoding unit performs error correction encoding processing for each transmission block bit string, and a CRC (Cyclic Redundancy Check) as a parity bit is added. In LTE-Advanced, a turbo code with a coding rate = 1/3 is used. When the number of data bits is N bits, the encoding unit outputs the following encoded bit strings to the sub-block interleaver.
Data bits (systematic bits): N bits First parity bit: N bits Second parity bit: N bits

  The sub-block interleaver interleaves the data bit, the first parity bit, and the second parity bit independently of each other.

  The buffering unit concatenates the encoded bit strings output from the sub-block interleave units.

  FIG. 4 is an explanatory diagram illustrating processing of the buffering unit in the channel encoding unit.

  FIG. 4A shows a case where the coding rate is 1/3. When the number of data bits is N bits, the number of bits of the encoded bit string is 3N bits. The encoded bit string generated by the buffering unit stores a data bit string at the head, and subsequently stores the first parity bit and the second parity bit alternately one bit at a time.

  According to FIG. 4B, the encoded bit string is then buffered in a circular buffer. Further, according to FIG. 4B, four bit reading positions (RV (Redundancy version)) are designated in LTE-Advanced, and RV can be selectively changed at each transmission. That is, the number of bits that can be transmitted is read from any position of RV. The number of bits that can be transmitted is determined by the number of resource blocks (RB (Resouce Block)) allocated to the receiver and MCS (Modulation and Coding Scheme).

According to FIG.4 (c), it divides into the encoding bit sequence which made the position of each RV the head. The number and arrangement of data bits and parity bits in the bit sequence differ depending on the number of assigned RBs and the selected RV. According to FIG.4 (c), the case where L bit is read from RV = 0 about each carrier signal is assumed. RV = 0 is defined at a position of δ bits from the beginning, and when L bits are read from RV = 0, the data bits (bit length N) and parity bits of the encoded bit string in each carrier signal are as follows: It becomes like this.
[For first carrier signal]
Data bit: From δ bit to (N + δ) bit Parity bit: From ((N + δ) +1) bit to (L- (N + δ)) bit [For second carrier signal]
Parity bits: (L- (N + δ) +1) bits to 2L bits Data bits: 1 bit to (δ-1) bits

[Interleave part]
The interleaving unit 12 divides each encoded bit string output from the channel encoding units 111 and 112 over the carrier signal based on the number of carrier signals, and based on the priority order according to the radio characteristic value, A carrier signal having a higher priority order of radio characteristic values is divided so as to include more data bits.

  Referring to FIG. 3, the interleaving unit 12 includes a radio characteristic storage unit 121, a bit string dividing unit 122, a bit string multiplexing unit 123, and an execution flag transmitting unit 124.

(Wireless characteristics storage unit)
The radio characteristic storage unit 121 stores the radio characteristic value for each carrier signal fed back from the receiving side. Examples of the radio characteristic value for each carrier signal are as follows.
(1) Radio quality value (2) Doppler frequency (3) Center frequency Of course, as a radio characteristic value, a combination of these values may be used to specify high-> low in priority order. The priority order is an order from a carrier signal having a good radio environment according to the radio characteristic value. When the wireless characteristic value is, for example, the reception level of the receiver, the priority order means the order in which the reception level is high. On the other hand, when the radio characteristic value is, for example, the receiver's SINR (Signal to Interference and Noise Power Ratio), the priority order means the order of the lower SINR. In the following, it is assumed that the radio characteristic value is a radio quality value, and the better the radio environment, the higher the radio quality value.

Here, the wireless quality value is measured for each reception antenna of the receiver and is fed back from the receiver to the transmitter. The radio quality value may be as follows, for example.
(1) Wideband CQI (Channel Quality that represents the reception level of the entire carrier signal band
Indicator) (index corresponding to the reception quality at the terminal)
(2) Multiple subbands with RB (Resource Block) assigned to the receiver
Average value of Subband CQI (3) RSRP (Reference Signal Received Power)
(4) RSPQ
(5) Fluctuation value between long-time average value and short-time average value in Wideband CQI (6) Fluctuation value between long-time average value and short-time average value in Subband CQI

Here, based on the variation difference between the first radio characteristic value of the first carrier signal and the second radio characteristic value of the second carrier signal stored in the radio characteristic storage unit 121 in the receiver, the bit string It is also preferable to control whether the dividing unit 122 and the bit string multiplexing unit 123 can be executed.
(1) When the variation difference in the radio characteristic value of the carrier signal is within a predetermined threshold, the bit string dividing unit 122 and the bit string multiplexing unit 123 are executed.
(2) When the variation difference in the radio characteristic value of the carrier signal is larger than the predetermined threshold, the bit string dividing unit 122 and the bit string multiplexing unit 123 are not executed. As in the existing technology, the encoded bit string is transmitted independently.

(Bit string division part)
The bit string dividing unit 122 divides each encoded bit string output from the channel encoding units 111 and 112 over the carrier signal based on the number of carrier signals, and based on the priority order according to the radio characteristic value. Then, a carrier signal having a higher priority order of radio characteristic values is divided so as to include many data bits. In the following description, it is assumed that the wireless characteristic value is the wireless quality value Wideband CQI. In this case, the priority order is wideband CQI.

  FIG. 5 is an explanatory diagram showing the processing of the interleave unit when the number of carrier signals is two.

According to FIG. 5, it is assumed that the CQI of the first carrier signal is higher than the CQI of the second carrier signal.
CQI of first carrier signal> CQI of second carrier signal

  The bit string dividing unit 122 divides the encoded bit string (number of bits: L bits) based on the radio quality value for each carrier signal. According to FIG. 5, the encoded bit string of L bits is divided into L / 2. When the number of transmittable bits based on the symbol mapping of each carrier signal is the same, the bit string dividing unit 122 divides each encoded bit string equally based on the number of carrier signals. Then, it is determined which of the first half L / 2 bit string and the second half L / 2 bit string contains many data bits.

  Regarding the first encoded bit string of FIG. 5, the latter half L / 2 bit string includes more data bits than the first half L / 2 bit string. In this case, the bit string dividing unit 122 distributes the latter half L / 2 bit string to be transferred to the first carrier signal having a high radio quality value, and converts the first half L / 2 bit string to the second carrier signal having a low radio quality value. Distribute to transfer.

  Similarly, for the second encoded bit string of FIG. 5, the first half L / 2 bit string contains more data bits than the second half L / 2 bit string. In this case, the bit string dividing unit 122 distributes the first half L / 2 bit string to transfer to the first carrier signal having a high radio quality value, and transfers the second half L / 2 bit string to the second carrier signal having a low radio quality value. Distribute as much as possible.

  The encoded bit string output from the bit string dividing unit 122 includes many data bits having higher importance than parity bits with respect to a carrier signal having a higher priority order of radio characteristic values. Thereby, the transmission efficiency can be improved.

(Bit string multiplexing unit)
The bit string multiplexing unit 123 multiplexes a plurality of encoded bit strings for each carrier signal output from the bit string dividing unit 122 according to symbol mapping. Specifically, a plurality of encoded bit sequences for each carrier signal are alternately multiplexed by the number of transmittable bits. The divided encoded bit string is multiplexed into an L-bit encoded bit string.

For example, the bit string multiplexing unit 123 performs multiplexing while extracting the number of bits corresponding to the symbol mapping as follows.
QPSK symbol mapping: 2 bits each 16 QAM symbol mapping: 4 bits 64 QAM symbol mapping: 6 bits each This represents the number of bits that can be transmitted per symbol for each symbol mapping.

  As a result, the interleave unit 12 outputs an L-bit encoded bit string for each carrier signal. These encoded bit strings are output to the frequency signal processing unit 13.

(Execution flag generator)
An execution flag including presence / absence of inter-carrier interleaving is generated to be transmitted to the receiver. The execution flag generation unit 124 transmits the execution flag to the receiver via the control band. The execution flag represents which encoded bit sequence is the target of interleaving. Specifically, for each encoded bit string, a flag “1” is included when interleaving is executed, and a flag “0” is included when it is not executed.

[Frequency signal processor]
Returning to FIG. 2, the first and second frequency signal processing units 131 and 132 are individually installed for each carrier signal. The frequency signal processing units 131 and 132 perform frequency signal processing on the encoded bit string output from the interleaving unit 13 for each carrier signal, and convert a waveform on the frequency axis into a waveform on the time axis. . The converted frequency signals are output to the transmission antennas 141 and 142, respectively.

  The first and second frequency signal processing units 131 and 132 have a common configuration, and are a scrambling unit, a symbol mapping unit, an RB (Resource Block) mapping unit, an IFFT (Inverse Fast Fourier Transform). A Fourier transform unit and a CP (Cyclic Prefix) insertion unit.

The scrambling unit scrambles the encoded bit string with a cell-specific Gold code.
The symbol mapping (constellation mapping) unit maps the transmission bit string of each carrier signal to a plurality of signal points (that is, a plurality of symbols) on the two-dimensional symbol arrangement diagram. As a result, a transmission symbol is generated for each carrier signal.
The RB mapping unit maps each symbol to a resource block.
The IFFT unit converts the waveform on the frequency axis of each transmission symbol into a waveform on the time axis. Specifically, a plurality of subcarriers are combined to generate a transmission signal of each carrier that is a multi-charier wave signal, and includes a serial-parallel converter and a parallel-serial converter.
The CP insertion unit inserts a CP into the transmission signal of each carrier and maintains orthogonality between subcarriers with respect to a delayed wave having a CP time length or less. This enhances robustness against multipath delayed waves.

  The transmission antennas 141 and 142 output the transmission signal in which the CP is inserted to the receiver 2 via radio.

  According to the embodiment described above, [number of carrier signals = 2, number of transmission bits of each carrier signal: the same] has been described for the LTE-Advanced system. The same number of RBs (Resource Blocks) as the number of carrier signals are allocated to each carrier signal, and the number of bits that can be transmitted by each carrier signal is the same.

Here, there are the following embodiments regarding the relationship between the number of carrier signals and the number of transmission bits.
[Number of carrier signals = 2, number of transmission bits of each carrier signal: the same] (FIG. 5 described above)
[Number of carrier signals> 2, Number of transmission bits of each carrier signal: the same]
[Number of carrier signals> 2, number of transmission bits of each carrier signal: different]

  FIG. 6 is an explanatory diagram showing the processing of the interleaving unit when the number of carrier signals is three.

[Number of carrier signals> 2, Number of transmission bits of each carrier signal: the same]
According to FIG. 6, it is assumed that the radio quality values of the carrier signals have the following relationship.
CQI-W2>CQI-W1> CQI-W3

  According to FIG. 6, the L-bit encoded bit string is divided into L / 3. When the number of transmittable bits based on the symbol mapping of each carrier signal is the same, the bit string dividing unit 122 divides each encoded bit string equally based on the number of carrier signals (3 according to FIG. 6). . That is, in this respect, FIG. 5 and FIG. 6 are the same.

  Then, it is determined which of the first half L / 3 bit string, the middle half L / 3 bit string, and the second half L / 2 bit string contains more data bits. Then, in order from the L / 3 bit string including a large number of data bits, distribution is performed in the order of the second carrier signal-> first carrier signal-> third carrier signal according to the radio quality value.

According to FIG. 6, the assignment is as follows.
First first half L / 3 bit string (data bit amount: small)-> Third carrier signal First middle half L / 3 bit string (data bit amount: medium)-> First carrier signal First second half L / 3 bit string (data bit amount: large)-> second carrier signal Second first half L / 3 bit string (data bit amount: large)-> second carrier signal Second middle half L / 3 bit string (data Bit amount: large)-> first carrier signal second latter L / 3 bit string (data bit amount: small)-> third carrier signal Thereby, the second carrier signal having a high radio quality value is A bit string having many data bits can be transmitted. On the other hand, a bit string having many parity bits is transmitted to the third carrier signal having a low radio quality value.
When bit strings are compared and there is no difference in the amount of data bits, a bit string close to the head may be assigned to a carrier having a high radio quality value (for example, the second first half L / Relationship between 3 bit string and second middle half L / 3 bit string).

  Then, the bit string multiplexing unit 123 multiplexes the number of transmittable bits corresponding to the symbol mapping. According to FIG. 6, the number of transmittable bits of all carrier signals is the same.

  FIG. 7 is an explanatory diagram illustrating processing of the bit string dividing unit when the number of transmission bits of each carrier signal is different.

[Number of carrier signals> 2, number of transmission bits of each carrier signal: different]
According to FIG. 7, the case where the number of carrier signals = 3 and the number of transmittable bits for each carrier signal is different will be described. Since the resource block allocated to the receiver is different for each carrier signal, the number of transmittable bits is also different. For example, the first carrier signal is QPSK, the second carrier signal is 16QAM, and the third carrier signal is 64QAM. According to FIG. 7, the number of transmittable bits for each carrier signal is defined as follows, and is output from the channel encoder 11 for each channel signal in units of this bit length.
First carrier signal: 6L bits Second carrier signal: 12L bits Third carrier signal: 18L bits Note that the radio quality value of each carrier signal has the following relationship.
CQI-W2>CQI-W1> CQI-W3

As shown in FIG. 7, the bit string dividing unit 122 divides each of the input first to third encoded bit strings into three. Here, each encoded bit string is divided at the following ratio.
6L: 12L: 18 = 1: 2: 3
This ratio is proportional to the number of transmittable bits in each carrier signal.

According to FIG. 7, since the first encoded bit string is 6L bits, it is divided into L bits, 2L bits, and 3L bits. Here, the carrier signal with the highest radio quality value is the second carrier signal, and the ratio of the number of transmittable bits is 1/3 (= 2/6). Therefore, the 2L-bit encoded bit string is divided so that the most data bits are included. On the other hand, the carrier signal with the lowest radio quality value is the third carrier signal, and the ratio of the number of transmittable bits is 1/2 (= 3/6). Therefore, the 3L-bit encoded bit string is divided so that the most parity bits are included. Then, the first encoded bit string is assigned as follows.
First first half 1L bit string (data bit amount: small)-> first carrier signal First middle half 3L bit string (data bit amount: small)-> Third carrier signal First second half 2L bit string (data bits Amount: large)-> second carrier signal

Similarly, according to FIG. 7, since the second encoded bit string is 12L bits, it is divided into 2L bits, 4L bits, and 6L bits. Then, the second encoded bit string is assigned as follows.
Second first half 2L bit string (data bit amount: small)-> first carrier signal Second middle half 4L bit string (data bit amount: small)-> Second carrier signal Second second half 6L bit string (data bits Quantity: large)-> third carrier signal

Similarly, according to FIG. 7, since the third encoded bit string is 18 L bits, it is divided into 3 L bits, 6 L bits, and 9 L bits. Then, the third encoded bit string is assigned as follows.
Third first half 3L bit string (data bit amount: small)-> first carrier signal Third middle half 6L bit string (data bit amount: small)-> second carrier signal Third second half 9L bit string (data bits Amount: small)-> 3rd carrier signal

  FIG. 8 is an explanatory diagram illustrating processing of the bit string dividing unit that selects a bit string including the most data bits.

According to FIG. 8, it is assumed that the carrier signal with the highest priority of the radio quality value (for example, Wideband CQI) is the second carrier signal, and the number of transmittable bits is 2L. At this time, it becomes a problem how to select a 2L bit string including the most data bits from the encoded bit string 6L. On the other hand, it is necessary to continuously secure the L bit string assigned to the first carrier signal and the 3L bit string assigned to the third carrier signal. Therefore, the position where the 2L bit string can be secured is one of the following four locations.
(Position a1) L to 2L bits (Position a2) 2L to 3L bits (Position a3) 4L to 5L bits (Position a4) 5L to 6L bits According to FIG. 8, the L to 2L bits at position a1 are the data bits. Selected as containing the most. Then, L to 2L bits at the position a1 are distributed to the second carrier signal having the highest radio quality value.

Next, a bit string to be distributed to the first carrier signal having the second highest radio quality value is selected. The transmittable bit string of the first carrier signal is L bits. Therefore, according to FIG. 8, among the remaining 3L to 6L bits, the continuous L bits including the most data bits are selected. However, it is necessary to continuously secure 3L bits to be distributed to the third carrier signal. Therefore, the position where the 1L bit string can be secured is one of the following two locations.
(Position b1) 3L bit (Position b2) 6L bit According to FIG. 8, the 3L bit at position b1 is selected as containing the most data bits. The 3L bits at position b1 are distributed to the first carrier signal with the second highest radio quality value.

  Finally, 4L to 6L bits are selected as the bit string to be distributed to the third carrier signal having the lowest radio quality value. The 4L to 6L bits are distributed to the third carrier signal having the lowest radio quality value.

  According to FIG. 8, the 6L bit encoded bit string has been described, but the 12L bit and 18L bit encoded bit strings are processed in the same manner.

  FIG. 9 is an explanatory diagram illustrating processing of the bit string multiplexing unit when the number of transmission bits of each carrier signal is different.

  According to FIG. 9, encoded bit strings having different bit lengths are distributed for each carrier signal. For this reason, when multiplexing is alternately performed based on the number of transmittable bits, there is no bit string to be multiplexed for one encoded bit string. According to the first encoded bit string in FIG. 9, since a divided bit string of L / 2L / 3L bits is assigned, a divided bit string of 3L bits remains at the end. When multiplexing of L bits is completed, only multiplexing of 2L bits and 3L bits is executed next. Further, when the 2L bit multiplexing is completed, the remaining 3L bits are stored as they are.

  When the number of CordWords = 2, spatial multiplexing transmission is applied for each carrier signal. Two transmission block bit strings are transmitted. In this case, since two encoded bit strings of each carrier signal are generated, one encoded bit string is selected for each carrier signal and interleaving is executed.

  FIG. 10 is a functional configuration diagram of a receiver for spectrum aggregation in the present invention.

  The functional configuration of the receiver in FIG. 10 executes processing in the opposite direction to the functional configuration of the transmitter in FIG. According to FIG. 10, the receiver 2 includes first and second receiving antennas 241 and 242, first and second frequency signal processing units 231 and 232, a deinterleaving unit 22, and first and second Channel decoding units 211 and 212 and a data receiving unit 20. These functional components excluding the transmission antenna are realized by causing a processor (for example, DSP or FPGA) mounted on the receiver 2 to execute a predetermined program using a memory.

  The reception signals received by the reception antennas 241 and 242 are output to the frequency signal processing units 231 and 232, respectively.

  The frequency signal processing units 231 and 232 convert each received signal into a plurality of received symbols by converting a time axis component into a frequency axis component for each input received signal. The frequency signal processing units 231 and 232 execute processing in the reverse direction with respect to the functional configuration of the frequency signal processing unit of the transmitter 1 of FIG. The frequency signal processing units 231 and 232 include a CP (Cyclic Prefix) deletion unit, an FFT (Fast Fourier Transform) unit, a symbol mapping unit, and a descrambling unit.

Each CP deletion unit deletes the CP from the reception signal of each carrier signal.
Each FFT unit converts a time axis component of each received signal into a frequency axis component. Each FFT unit extracts a plurality of received symbols from the received signal of each carrier, which is a multicarrier wave signal, and includes a serial-parallel converter and a parallel-serial converter. The plurality of received symbols are output to the symbol demapping unit.
A symbol demapping (constellation demapping) unit demaps a plurality of detected signal points (a plurality of symbols).
The descrambling unit restores the scrambled received bit string.

  The deinterleave unit 22 is provided in common for a plurality of carrier signals. According to the present invention, a plurality of received bit strings are deinterleaved across a plurality of carrier signals. The deinterleave unit 22 receives an execution flag from the transmitter 1 via the control channel. When the execution flag indicates “interleaved execution”, the deinterleaving process is executed. The deinterleaving process is performed in the reverse direction with respect to the functional configuration of the interleaving unit in FIG.

  The deinterleaving unit 22 demultiplexes and separates each encoded bit sequence output from the frequency signal processing units 231 and 232 for each carrier signal across the carrier signal. For example, when a bit string based on FIG. 5 is received, it is separated into L / 2 bit strings for each carrier signal. The separated encoded bit strings (L / 2 bit strings) are combined and restored for each carrier signal.

  The channel decoding units 211 and 212 decode the encoded bit string output from the deinterleaving unit 22 for each carrier signal. CRC parity bits are removed by error correction decoding.

  The receiver 2 transmits the radio quality value for each of the reception antennas 241 and 242 from the transmission antenna to the transmitter 1.

  The number of data bits included in the circular buffer in the channel encoding unit 111 of the transmitter 1 is uniquely determined by MCS (Modulation and Coding Scheme) information and RB (Resource Block) number assigned at the time of initial transmission. The transmitter 1 has already transmitted the MCS information and the number of RBs to the receiver 2 through the control channel. That is, the same receiver as the circular buffer generated by the transmitter can be duplicated. Also, the transmitter 1 has already transmitted to the receiver 2 regarding RV information indicating from which position the circular buffer is read. Therefore, by using the wireless quality value, the circular buffer, and the RV information, the processing algorithm executed by the transmitter is executed in the same manner, so that which bit sequence is transmitted to which carrier signal without transmitting correlation information (allocation information). Can be uniquely determined by the receiver. Of course, the transmitter 1 may transmit interleave information to the receiver 2.

  FIG. 11 is a graph showing average SNR versus bit error rate (BER) characteristics.

It is assumed that the average SNR (Signal-to-Noise Ratio) of the first carrier signal is set 8 dB higher than the average SNR of the second carrier signal.
[No interleaving]: Indicates characteristics when transmission blocks are transmitted independently for each carrier signal without interleaving between carrier signals.
[Interleaved (Random)]: An encoded bit string is randomly multiplexed, and a bit string is randomly assigned to each carrier signal without considering the positions of data bit bits and parity bits.
[Interleaved (Invention)] is the execution of the interleaving unit in the invention.

  According to FIG. 11, it can be understood that [with interleaving (present invention)] and [with interleaving (random)] have improved BER (Bit Error Rate) characteristics over “without interleaving”. This is because the frequency diversity gain resulting from the difference in the propagation characteristics of different frequency bands is obtained by executing interleaving across the carrier signals.

  Further, when [with interleaving (present invention)] and [with interleaving (random)] are compared, it can be understood that the characteristic of [with interleaving (present invention)] is better. This is because the decoding characteristics are improved by preferentially allocating a bit string including many data bits to a carrier signal having a high average SNR.

  As described above in detail, according to the transmitter, receiver, method, and program for spectrum aggregation of the present invention, the transmission bit string for each carrier signal is spread as much as possible across the carrier signals in different frequency bands. By transmitting a transmission signal that is randomly interleaved, the transmission bit string can be correlated, and the frequency diversity gain can be improved.

  Various changes, modifications, and omissions of the above-described various embodiments of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

DESCRIPTION OF SYMBOLS 1 Transmitter 10 Data transmission part 111,112 Channel encoding part 12 Interleaving part 121 Radio | wireless characteristic memory | storage part 122 Bit stream division part 123 Bit stream multiplexing part 124 Execution flag generation part 131,132 Frequency signal processing part 141,142 Transmission antenna 2 Reception 20 Data receiving unit 211, 212 Channel decoding unit 22 Deinterleaving unit 231, 232 Frequency signal processing unit 241, 242 Receiving antenna

Claims (9)

A transmitter for spectrum aggregation that transmits simultaneously from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other,
Channel coding means for performing error correction coding on a bit string of a transmission block for each carrier signal and outputting a coded bit string including data bits and / or parity bits divided based on the number of resource blocks;
Interleaving means for interleaving each coded bit string output from the channel coding means across a carrier signal;
For each carrier signal, frequency signal processing is performed on the encoded bit string output from the interleaving means, and frequency signal processing means for outputting to each transmitting antenna,
The interleaving means is
Wireless characteristic storage means for storing a wireless characteristic value for each carrier signal;
Each encoded bit string output from the channel encoding means is divided based on the number of carrier signals across carrier signals, and based on a priority order corresponding to the wireless characteristic values, Bit string dividing means for dividing a high carrier signal so as to include many data bits;
Bit string multiplexing means for multiplexing a plurality of encoded bit strings for each carrier signal output from the bit string dividing means according to symbol mapping;
A transmitter for spectrum aggregation, comprising execution flag generation means for generating an execution flag including whether or not inter-carrier interleaving is performed to be transmitted to a receiver. The interleaving means is
As a radio characteristic value for each carrier signal, a radio quality value, a Doppler frequency, a center frequency and a combination thereof are used.
The transmitter for spectrum aggregation according to claim 1, wherein the priority order is an order from a carrier signal having a good radio environment according to the radio characteristic value. When the number of transmittable bits based on the symbol mapping of each carrier signal is the same,
The bit string dividing means divides each encoded bit string equally based on the number of carrier signals,
3. The bit string multiplexing means alternately multiplexes a plurality of encoded bit strings for each carrier signal output from the bit string dividing means for each number of transmittable bits. Transmitter for spectrum aggregation. When the number of transmittable bits based on the symbol mapping of each carrier signal is different,
The bit string dividing means divides each encoded bit string at a ratio according to the number of transmittable bits of each carrier signal,
The bit string multiplexing means alternately multiplexes a plurality of encoded bit strings for each carrier signal output from the bit string dividing means by the number of transmittable bits according to the number of transmittable bits for each carrier signal. The transmitter for spectrum aggregation according to claim 1 or 2. The bit sequence multiplexing means of the interleaving means multiplexes the number of bits according to the symbol mapping QPSK symbol mapping: 2 bits each 16 QAM symbol mapping: 4 bits 64 QAM symbol mapping: 6 bits each The transmitter for spectrum aggregation according to claim 3 or 4.   The bit string dividing means and the bit string multiplexing means are executed only when a difference in radio characteristic values between carrier signals is within a predetermined threshold with reference to the radio characteristic storage means. The transmitter according to any one of claims 1 to 5. A receiver for communication with the transmitter according to any one of claims 1 to 6, wherein the receiver for spectrum aggregation receives simultaneously from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other. Because
For each carrier signal, the received signal output from the receiving antenna is subjected to frequency signal processing, and the frequency signal processing means for outputting each encoded bit string, and each encoding signal output from the frequency signal processing means across the carrier signal A deinterleaving means for deinterleaving the bit string;
Channel decoding means for decoding the encoded bit string output from the deinterleaving means for each carrier signal;
The deinterleaving means is
The execution flag including the presence / absence of inter-carrier interleaving is received from the transmitter,
Using the execution flag, each encoded bit string output from the frequency signal processing means across the carrier signal is demultiplexed and separated for each carrier signal,
A receiver for spectrum aggregation, characterized in that the separated encoded bit strings are combined and restored for each carrier signal. A transmission method for spectrum aggregation in a transmitter that simultaneously transmits from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other,
A first step of performing error correction coding on a bit string of a transmission block for each carrier signal and outputting a coded bit string including data bits and / or parity bits, which is partitioned based on the number of resource blocks;
A second step of interleaving each encoded bit string output from the channel encoding means across a carrier signal;
A third step of performing frequency signal processing on the encoded bit sequence output from the interleaving means for each carrier signal, and outputting to each transmitting antenna;
Have
The second step is
A radio characteristic storage unit that stores a radio characteristic value for each carrier signal fed back from the receiver;
Each encoded bit string output from the channel encoding means is divided based on the number of carrier signals across carrier signals, and based on a priority order corresponding to the wireless characteristic values, Dividing from a high carrier signal to include many data bits;
Multiplexing a plurality of encoded bit sequences for each carrier signal output from the bit sequence dividing means according to symbol mapping;
A transmission method for spectrum aggregation, comprising: generating an execution flag including whether or not inter-carrier interleaving is performed to be transmitted to the receiver. A transmission program for causing a computer mounted on a transmitter for spectrum aggregation to simultaneously transmit from a plurality of antennas for each of a plurality of carrier signals whose frequency bands are separated from each other,
Channel coding means for performing error correction coding on a bit string of a transmission block for each carrier signal and outputting a coded bit string including data bits and / or parity bits divided based on the number of resource blocks;
Interleaving means for interleaving each coded bit string output from the channel coding means across a carrier signal;
For each carrier signal, frequency signal processing is performed on the encoded bit string output from the interleaving means, and frequency signal processing means for outputting to each transmitting antenna,
The interleaving means is
Radio characteristic storage means for storing a radio characteristic value for each carrier signal fed back from the receiver;
Each encoded bit string output from the channel encoding means is divided based on the number of carrier signals across carrier signals, and based on a priority order corresponding to the wireless characteristic values, Bit string dividing means for dividing a high carrier signal so as to include many data bits;
Bit string multiplexing means for multiplexing a plurality of encoded bit strings for each carrier signal output from the bit string dividing means according to symbol mapping;
A transmission program for spectrum aggregation, characterized by causing a computer to function as an execution flag generation means for generating an execution flag including whether or not inter-carrier interleaving is performed to be transmitted to a receiver.

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