JP3712070B2 - COMMUNICATION SYSTEM, TRANSMITTING APPARATUS AND TRANSMITTING METHOD, RECEIVING APPARATUS AND RECEIVING METHOD, CODE MULTIPLEXING METHOD, AND MULTICODE DECODING METHOD - Google Patents

Description

  The present invention relates to a communication system, a transmission device and a transmission method, a reception device and a reception method, a code multiplexing method, and a decoding method of a multiplexed code, which operate in a multiple access environment in which a plurality of mobile terminals communicate simultaneously with one base station. In particular, the present invention relates to a communication system, a transmission device and a transmission method, a reception device and a reception method, a code multiplexing method, and a multiplexing code decoding method that extend capacity by removing interference inside and outside a cell.

  More particularly, the present invention relates to a transmission apparatus and communication system that operates with repetition of as short a frequency as possible to increase capacity, a transmission method, a reception apparatus and reception method, a code multiplexing method, and a decoding method of a multiplexed code. The present invention relates to a communication system, a transmission apparatus and a transmission method, a reception apparatus and a reception method, a code multiplexing method, and a multiplexing code decoding method that increase the capacity by realizing one-frequency repetition by a non-spreading cellular system.

  Mobile communications originated from the discovery of electromagnetic waves in the first place, and since then research and development has been promoted due to the necessity of communications with ships, aircraft and trains. In addition, automobiles and people have been expanded to communicate. As for transmission data, not only telegraph and telephone but also computer data and multimedia contents such as images can be transmitted.

  Recently, mobile terminals have been rapidly reduced in size and price due to improvements in manufacturing technology. In addition, with the expansion of information and communication services, mobile terminals are becoming personalized like mobile phones. In addition, the user base has been expanding due to the liberalization of communications and the reduction of communication charges.

  Mobile communication is based on the fact that a mobile station such as an in-vehicle phone or a mobile phone finds the nearest base station and exchanges radio waves between the mobile station and the base station. A communicable range within which radio waves from one base station can reach is called a “cell”. The cell is usually a circle with a predetermined radius centered on the base station antenna. And a communication service area is comprised by arrange | positioning a cell without gap.

  FIG. 19 schematically illustrates a cell configuration in a mobile radio communication system in which a service area is expanded by a plurality of base stations represented by a cellular system. By installing base stations (not shown) at certain fixed intervals and laying a plurality of cells provided by each base station seamlessly as shown in the figure, a wide service area can be obtained. Built.

  The mobile communication system uses a cell in this way by limiting the radio waves of the base station to reach only in the cell, and repeatedly using the same frequency in other cells. By effectively using frequency resources, or by dividing the cell into cells, the radio wave output for communication is reduced, and the mobile unit normally mounted as a battery-powered portable device is reduced in size and power consumption. This is because there is a merit such as. Recently, with the increase in the number of cellular phone users (cellular), it is increasingly required to accommodate as many users as possible in the cell and to make the best use of limited frequency resources. . There are a plurality of mobile terminals in one cell, and these communicate with one base station at the same time. Therefore, when viewed from the base station side, it is necessary to detect which signal belongs to which user (multi-user detection), that is, to multiplex radio signals and detect which signal belongs to which user (multi-user detection).

  Conventionally, as a multiple access technique in wireless communication, a frequency division multiple access (FDMA) and a time division multiple access (TDMA) adopted in the second generation PDC (Personal Digital Cellular). Access), code division multiple access (CDMA) adopted in the third generation, and the like are known.

  TDMA is a communication method in which a communication channel is divided in advance by time slots on the time axis, and a different time slot is assigned to each mobile terminal that communicates at the same time, and a digital method is assumed. The digital cellular phone system in Japan performs time division multiplexing of 3 channels or 6 channels.

  In addition, FDMA is a system in which communication is performed by assigning different frequencies between mobile terminals that communicate simultaneously (that is, for each call channel). That is, a large number of channels used for communication are arranged on the frequency axis, and vacant channels are appropriately assigned and used. FDMA can handle both analog and digital communication systems. In Japan, FDMA has been adopted for analog car phones and mobile phones.

  CDMA is a scheme in which a wide frequency is shared by a plurality of mobile terminals using spread spectrum. Each time a mobile terminal performs communication, a spread sequence for spread spectrum is assigned, and a communication signal is spread by this spread sequence and transmitted. Since the mobile terminal uses a common frequency, all communication signals of other stations become interference for the own station, and the performance of extracting the received signal from the interference greatly affects the reception level.

  Here, the communication capacity (capacity) is defined as the number of users that can be accommodated per channel per cell. In a wireless communication environment in which mobile communication spreads rapidly and widely and a large number of mobile stations exist in the same cell, how to expand capacity with a small amount of resources becomes the biggest issue.

  In TDMA and FDMA, different frequencies are allocated between adjacent cells, and a plurality of frequencies are repeatedly used. The capacity of these schemes depends only on the number of channels. In CDMA, the same frequency is used simultaneously between cells and within a cell, so that it receives interference inside and outside the cell. That is, in CDMA, capacity depends on the amount of interference, not the number of channels.

  In FDMA and TDMA, the number of users that can be accommodated in one cell is limited to the number of channels that are obtained by dividing a usable frequency band, so that the capacity is small. Further, it is impossible to repeat the same frequency between adjacent cells, and the capacity of the entire communication service is small.

  In CDMA, code division is performed using spreading sequences including orthogonal and quasi-orthogonal codes. However, since users in a cell share the same frequency, all other users' signals become interference waves. Since the base station can know the spreading sequence to be used for each mobile terminal, the base station can detect each user's signal, but on the other hand, the mobile terminal uses other mobile terminals. Since the spreading sequence cannot be known, user detection is not realized. In addition, it is sufficient that the spreading sequences are all orthogonal. However, since the non-orthogonal component becomes an interference component, the number of users that can be accommodated is small with respect to the number of channels created by the pseudo orthogonal code. In addition, since CDMA uses a wide frequency band due to spreading, the capacity is small even if one-frequency repetition can be realized.

  In the CDMA system, each signal can be detected, that is, multi-user detection can be performed by applying an interference cancellation technique such as an interference canceller IC (Interference Canceller) (for example, see Patent Document 1). This IC demodulates the received signal consisting of the sum of the incoming signal and noise transmitted from each station on the transmitting side and propagated through each propagation characteristic, in descending order of reception power, and cancels its own signal. By repeating the process, all received signals can be detected.

  When inter-cell multi-user detection is performed by applying interference cancellation technology such as IC, the receiving station detects the incoming signals from the transmitting and receiving stations inside and outside the cell as desired signals. Thus, adjacent or neighboring cells can share a channel having the same spatial, temporal and frequency. Therefore, it is possible to realize a multi-cell configuration by one-frequency repetition using TDMA or FDMA, and the frequency utilization efficiency increases, and the capacity (communication capacity) increases at the same utilization efficiency.

  However, in the vicinity of the cell boundary, it is expected that the difference between the interference of other cells and the received power of the desired signal is expected to be small, and the received signals of both may be equal power. Under such circumstances, there is a problem that the IC cannot perform decoding and cancellation.

JP 2002-84214 A

  An object of the present invention is to provide an excellent communication system, transmission apparatus and transmission method, reception apparatus and reception method, code multiplexing method, and multiplexing capable of extending the capacity (communication capacity) by removing interference inside and outside the cell. The object is to provide a method for decoding a code.

  A further object of the present invention is to provide an excellent communication system, transmitting apparatus and transmitting method, receiving apparatus and receiving method, code multiplexing method, and decoding method of multiple codes, which can increase the capacity by operating with a frequency repetition as short as possible. Is to provide.

  A further object of the present invention is to provide an excellent communication system, transmitting apparatus and transmitting method, receiving apparatus and receiving method, code multiplexing method and multiple code capable of increasing the capacity by realizing one frequency repetition by a non-spreading method. It is to provide a decoding method.

The present invention has been made in consideration of the above-mentioned problems, and a first aspect thereof is a communication system that increases the capacity by realizing one-frequency repetition by a non-spreading method,
On the transmitting station side, the transmission information is divided into a plurality of frames, each frame is encoded, each encoded signal is power-amplified with a different amplitude, and the amplified signals are combined and interleaved over all signals. Send the transmission signal obtained by doing,
On the receiving station side, the transmission signal is deinterleaved, sequentially decoded from a code having a large SINR (signal-to-interference and noise power ratio), and the decoded signal is re-encoded and sequentially canceled from the transmission signal. To reproduce the original split frame,
This is a communication system characterized by the above.

  However, “system” here refers to a logical collection of a plurality of devices (or functional modules that realize specific functions), and each device or functional module is in a single housing. It does not matter whether or not.

  According to the communication system according to the first aspect of the present invention, the receiving station can separate the desired wave and the undesired wave using the difference in the interleave pattern. Therefore, multiple access can be realized by using different interleave patterns for each user. Alternatively, a non-spread multi-cell system with one frequency repetition can be realized by using a different interleave pattern for each cell.

  Therefore, according to the communication system according to the first aspect of the present invention, the power of the interference signal can be distributed and reduced. When the received power of the desired signal and the interference signal is equal, which is a problem in the conventional inter-user multi-user detection, decoding can be performed by applying the present invention. In addition, the average transmission power can be reduced by appropriately designing the amplitude of the power amplifier.

  Here, on the transmitting station side, the amplitude amplification ratio for each frame may be changed according to the decoding capability on the receiving station side. Here, the decoding capability on the receiving station side can be determined based on the number of interference signals, noise power, and the number of codewords per frame.

  Further, if the number of code multiplexes increases, the decoding capability improves, but the processing becomes complicated. Therefore, the number of code multiplexes is determined on the transmitting station side according to the decoding capability or processing capability realized on the receiving station side.

A second aspect of the present invention is a transmission apparatus or transmission method for transmitting information by a non-spreading method,
Frame dividing means or step for dividing transmission information into a plurality of frames;
Means or steps for encoding each frame;
Power amplification means or step for power amplifying each encoded signal with a different amplitude;
Interleaving means or steps for grouping the amplified signals together for interleaving across all signals;
A transmission means or step for transmitting a transmission signal obtained by interleaving; and
A transmission apparatus or a transmission method.

  According to the transmission apparatus or the transmission method according to the second aspect of the present invention, the receiving station can separate the desired wave and the interference wave using the difference in the interleave pattern. By using a different interleave pattern for each cell, a non-spread multi-cell system with one frequency repetition can be realized. Also, multiple access can be realized by using different interleave patterns for each user.

  The power amplification means or step may change the amplitude amplification ratio for each frame according to the decoding capability on the receiving station side. Here, the decoding capability on the receiving station side can be determined based on the number of interference signals, noise power, and the number of codewords per frame.

  The frame dividing means or step may determine the number of code multiplexes according to the decoding capability or processing capability realized on the receiving station side.

  In the transmission apparatus or the transmission method according to the second aspect of the present invention, the ratio of amplitude amplification for each frame is changed according to the decoding capability on the receiving station side, for example, the number of interference signals and noise power, The amplitude value is calculated by the number of codes having different amplitude values. Here, since the received power of the interference signal varies, the interference power is set to be the worst value, and the amplitude value of the code is calculated assuming that the power of the interference wave is equal to that of the desired wave. ing.

  However, in an actual propagation path, the power of a plurality of interference waves is rarely equal to that of a desired wave, and there is a problem that transmission power loss occurs in most situations. In addition, since cell arrangement conditions and traffic that is dense and small in terms of location and time are not taken into account, if code design is performed according to a severe situation, transmission power loss occurs in a good situation.

  Therefore, the transmission device or the transmission method according to the second aspect of the present invention further includes a propagation path condition monitoring unit or step for monitoring a situation such as traffic at a certain interval, and in the power amplification unit or step, The number of interference signals to be considered and the number of code words in one frame may be changed according to the situation, and the amplitude value of each code may be updated as needed. Further, in order to control the amplitude value more finely, a margin may be given to the amplitude value. However, when the number of code words in one frame is changed, it is necessary to notify the number of code words to the receiver side. On the other hand, when only the number of interference signals to be considered and the margin of the amplitude value are changed, there is no need to notify the receiver of information.

  Here, the received signal is roughly divided into two signals, a desired signal, an interference signal to be considered, and an interference signal not to be considered according to the magnitude of the received power. The “interference signal to be considered” here is a main interference signal having a large received signal that greatly affects the desired signal.

  By limiting the number of interference signals to be considered, the interval of the amplitude ratio is narrowed, and as a result, the transmission power can be kept lower. In this case, however, there are actually many other interference waves. Here, the power sum of the interference waves not considered as these interference waves is referred to as “residual interference power”. Residual interference power increases noise when viewed from the receiver, and causes degradation of decoding characteristics.

  On the other hand, when the number of interference signals to be considered increases, the average transmission energy increases, and when the number of code words in one frame increases, the average transmission energy decreases. However, if the number of codewords is increased, the number of bits per code is reduced, so that the decoding capability is reduced when a turbo code is used.

  Further, in the power amplifying means or step, the residual interference power (consisting of the sum of power of interference waves not considered as interference waves) may be taken into account when calculating the amplitude value of each code. For example, the base station collects information on the average residual interference power from each terminal and calculates the amplitude value of each code in consideration of the value. When the average residual interference power is large, there is a possibility that the low-level code is buried in the residual interference and cannot be decoded, so the amplitude of the low-level code is increased. In this case, the amplitude of the high-level code also increases, but in order to maintain the average transmission power, the number of interference waves to be considered, the number of codes in one frame, the amplitude value margin, and the like are adjusted.

The third aspect of the present invention is to encode each frame formed by dividing transmission information, power-amplify each encoded signal with a different amplitude, and combine all the amplified signals into all signals. A receiving apparatus or a receiving method for receiving a transmission signal obtained by performing interleaving over
Deinterleaving means or step for deinterleaving the transmission signal;
Decoding means or step for sequentially decoding from a code having a large SINR;
A signal cancellation means or step for re-encoding the decoded signal and sequentially canceling the transmission signal;
A receiving apparatus or a receiving method.

  According to the receiving apparatus or the receiving method according to the third aspect of the present invention, the desired wave and the interference wave can be separated by deinterleaving using the difference in the interleaving pattern used on the transmitting station side. it can. By using a different interleave pattern for each cell, a non-spread multi-cell system with one frequency repetition can be realized. Also, multiple access can be realized by using different interleave patterns for each user.

  In addition to this method, signal diffusion processing may be added. However, the spreading mentioned here is for reducing the power of the interference signal, and is not intended to identify or separate users as in the CDMA system.

  As described above in detail, according to the present invention, an excellent communication system, a transmission device and a transmission method, a reception device and a reception method, which can increase the capacity by realizing one-frequency repetition by a non-spreading method, A code multiplex method and a multiplex code decoding method can be provided. Since the present invention performs user detection by a non-spreading method, it is essentially different from the so-called CDMA method.

  According to the present invention, the power of the interference signal can be distributed and reduced. When the received power of the desired signal and the interference signal is equal, which is a problem in the conventional inter-user multi-user detection, decoding can be performed by applying the present invention. In addition, the average transmission power can be reduced by appropriately designing the amplitude of the power amplifier.

Further, according to the present invention, by changing the amplitude value of the transmission signal according to the propagation environment of the system, it is possible to improve the decoding characteristic while maintaining the average energy of the transmission symbol.

  Moreover, according to the present invention, the amplitude value of each code can be freely set by changing the number of codes that give different amplitude values and the number of interference signals to be considered.

  Further, according to the present invention, it is possible to design an optimum system by making the amplitude value of the transmission code variable according to the cell arrangement or the crowded time zone or place. Further, by providing a margin for the designed amplitude value of each code, code design with a higher degree of freedom becomes possible.

  Further, according to the present invention, the receiver can be set in standby by designing the amplitude value of each code by changing only the number of interference signals to be considered and the margin of the amplitude value without changing the number of codes giving different amplitude values. Decryption processing can be performed without obtaining specific information.

  Further, according to the present invention, by checking the interference power of the entire system in advance, it is possible to determine the optimum parameter for determining the amplitude value of each code, and the decoding characteristics are improved.

  Other objects, features, and advantages of the present invention will become apparent from more detailed description based on embodiments of the present invention described later and the accompanying drawings.

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

A. First embodiment
A-1. Transceiver system Here, of the multi-cell radio systems, such as cellular, without using a spreading sequence multiple access (i.e. not performed CDMA) Consider the non-diffusion method. That is, TDMA or FDMA is used as multiple access, and user signals in the cell are arranged orthogonally.

  Further, an OFDM (Orthogonal Frequency Division Multiplexing) system is adopted as a modulation system. OFDM is a type of multi-carrier transmission scheme, and the frequency of each carrier is set so that the carriers are orthogonal to each other within a symbol interval. Further, by inserting a guard interval, it is possible to remove the influence of delayed waves and interference from other users in the cell. Therefore, there is no interference in the cell.

  In the wireless communication system described below, one frequency repetition is assumed. That is, since the same frequency is used in adjacent cells, there is interference between cells. The present invention is a technique for removing the inter-cell interference and correctly decoding a desired signal.

  FIG. 1 schematically shows a transmission model according to an embodiment of the present invention. In the example shown in the figure, it is assumed that a certain transmitting station (user A) multiplexes and transmits two codes and receives interference from another station (user B) on the propagation path. In the illustrated example, the signal power ratio is 4: 1.

In the transmitter of user A, the transmission information is serial-parallel converted and divided into I _AX (101) and I _AY (102), and encoded using encoder X (103) and encoder Y (104), respectively. Turn into. The configurations of the encoder X (103) and the encoder Y (104) may be the same.

  The encoded signal is amplified by power amplifiers (105) and (106) having different amplitudes. In the present embodiment, the power amplifiers (105) and (106) are amplitude amplifiers for digital signal processing, and are not power amplifiers.

  The amplified signals AX and AY are merged by parallel-serial conversion, and are randomly interleaved (mixed) by the interleaver A (107) over two code sections. The interleaved signal TxA becomes a transmission signal.

On the other hand, also in the user B existing in a cell different from the user A, similarly, the transmission information is serial-parallel converted and divided into I _BX (111) and I _BY (112), respectively. Encoded by the encoder Y (114), further amplified by the power amplifiers (115) and (116) having different amplitudes, and the amplified signals BX and BY are merged and randomized by the interleaver B (117). A transmission signal TxB is obtained by interleaving.

  The encoder X (113) and the encoder Y (114) may be the same as the user A. The amplitude patterns of the power amplifiers (115) and (116) are arbitrary, but may be the same as or different from those of the user A. In this specification, for the sake of simplicity, the amplitude pattern is the same for each user, and is 4 and 1.

  However, the interleave pattern is unique at least in a neighboring cell that receives interference. In the example shown in the figure, the interleave patterns of the interleaver A (107) and the interleaver B (117) are different.

  By using a different interleave pattern for each cell, a non-spread multi-cell system with one frequency repetition can be realized. Also, multiple access can be realized by using different interleave patterns for each user.

  In the communication path, the transmission signals TxA and TxB from the users A and B are added to obtain an interference signal AX + AY + BX + BY (120).

  FIG. 2 schematically shows the configuration of the reception model corresponding to the transmitter configuration shown in FIG. As will be described below, the receiver can receive signals that have undergone interference on the communication path, and can separate and detect each signal. However, in the figure, the noise component is not included in the signal component.

  The transmission signals from user A and user B are combined and reach the receiver. The received signal (120) is AX + AY + BX + BY (see FIG. 1).

First, the received signal ( 120 ) is deinterleaved using user A's deinterleaver A (201). In this embodiment, the interleaving pattern is unique at least in neighboring cells that are subject to interference. Here, there is no correlation in the interleave pattern between user A and user B (described above). Therefore, the output of the deinterleaver A (201) is AX + (BX + BY) / 2, and the interference component is halved.

Next, the output signal of the deinterleaver A (201) is supplied to the decoder X (202) for decoding. In the decoder X (202), only the code X having the largest SINR (that is, the most probable) is decoded. If the received power of desired signal AX is sufficiently larger than the power (BX + BY) / 2 of the interference signal, AX can be decoded without error, and decoded signal I _AX can be obtained.

  Here, assuming that signals from user A and user B are received with equal power, the power ratio of desired signal AX and interference signal (BX + BY) / 2 is 4: 2.5, that is, 1.6 times (2. 0 dB). Therefore, by using a turbo code or the like having a required CIR (Carrier to Interference power Ratio) of 2.0 dB or less as the original code, it is possible to realize error-free decoding.

Further, the received signal ( 120 ) is deinterleaved using the user B deinterleaver B (211). Since there is no correlation in the interleave pattern between user A and user B, the output of deinterleaver B (211) is BX + (AX + AY) / 2, and the interference component is halved.

Next, the output signal of the deinterleaver B (211) is supplied to the decoder X (212) for decoding. The decoder X (212) decodes X, which is a code having a large SINR. Since the received power of desired signal BX is sufficiently larger than the power (AX + AY) / 2 of the interference signal, signal I _BX decoded without error can be obtained.

Next, the components of the decoded signals I _AX and I _BX are canceled from the received signal.

The signal I _AX decoded by the decoder X (202) is re-encoded by the encoder X (203) and then amplified using the power amplifier (204). The interleaver A (205) receives the decoded signal AX and the all-zero signal as the other signal AY to be merged, and performs interleaving. The interleaver A (205) uses the same interleave pattern with the same configuration as the transmitter interleaver A (107). As a result of the interleaving, a replica of the transmission signal of user A having only the signal component of AX is generated, so that the signal component AX is canceled from the received signal (120) using the differentiator (216), and the output signal AY + BX + BY is obtained. . If there is a fluctuation such as fading in the propagation path, a propagation path fluctuation replica is multiplied.

Similarly, the signal I _BX decoded by the decoder X (212) is re-encoded by the encoder X (213) and then amplified using the power amplifier (214). The interleaver B (215) receives the decoded signal BX and the all-zero signal as the other signal BY to be merged, and performs interleaving. Interleaver B (215) uses the same interleave pattern with the same configuration as interleaver B (117) on the transmitter side. Interleaving result, the replica of the transmission signal of the user B with a signal component of BX only is generated to cancel the signal components B X from the received signal (120) using a differentiator (206), an output signal AX + AY + BY obtain.

  Finally, the second power level signals AY and BY from each transmitter are decoded. First, the output signal (AX + AY + BY) of the differentiator (206) is deinterleaved again using the deinterleaver A (207). The deinterleaver A (207) uses the same interleave pattern with the same configuration as the deinterleaver A (201).

The output of the deinterleaver A (207) becomes AX + BY / 2 and AY + BY / 2, and the power of the interference signal BY is halved. Next, the decoder Y (208) decodes this signal AY + BY / 2 with respect to Y which is a code having a large SINR. If the difference between desired signal AY and interference power BY / 2 is sufficiently large, AY can be decoded without error by decoder Y (208), and decoded signal I _AY can be obtained.

  Similarly, the output signal (AY + BX + BY) of the differentiator (216) is deinterleaved again using the deinterleaver B (217). The deinterleaver B (217) uses the same interleave pattern with the same configuration as the deinterleaver B (211).

The output of the deinterleaver B (217) is BX + AY / 2 and BY + AY / 2, and the power of the interference signal AY is halved. Next, the decoder Y (218) decodes Y which is a code having a large SINR of the signal BY + AY / 2. Here, if the difference between desired signal BY and interference power AY / 2 is sufficiently large, BY can be decoded without error by decoder Y (218), and decoded signal _IBY can be obtained.

Through the above procedure, all signals I _AX , I _AY , I _BX , and I _BY transmitted from user A and user B are decoded.

  In the above-described embodiment, the received signals of all users are input to the first-stage deinterleaver A (201) and deinterleaver B (211), and decoded and canceled from signals having a large SINR in cascade. However, the gist of the present invention is not limited to this. For example, iterative decoding can be applied to increase the decoding accuracy. The procedure for iterative decoding is described below.

  First, after decoding AX, the differencer (216) obtains a signal AY + BX + BY obtained by canceling AX from the received signal AX + AY + BX + BY.

  Next, by inputting the signal from which AX has been canceled to the deinterleaver B (211) for the user B, BX + AY / 2 is obtained. Since AX that is an interference component has already been canceled in this signal, the decoding accuracy of BX is improved.

  Similarly, after decoding BX, a signal AX + AY + BY in which BX is canceled is obtained from the received signal AX + AY + BX + BY by the subtractor, and this is input to the deinterleaver A (201) for user A, thereby obtaining AY + BY / 2. It is done. Since BX that is an interference component has already been canceled in this signal, the decoding accuracy of AX is improved.

  In this way, it is possible to perform iterative decoding by giving each other's decoding result as the other party's input across users.

Iterative decoding can also be applied between codes at different stages (amplified by power amplifiers having different amplitudes). In the example shown in FIG. 2, AX is first decoded, then AY is decoded, and the decoding process is completed. By re-encoding the decoded signal I _AY , canceling the re-encoded AX and AY from the received signal (120), and inputting it to the first deinterleaver (211) of the user B, the BX And BY can be decoded.

A-2. Setting method of amplitude value of power amplifier The code multiplexing method in the inter-cell multi-user detection (IC-MUD) described with reference to FIG. 1 and FIG. 2 is used as UCM (Universal Code Mixing). ). IC-MUD is a technique for realizing one-frequency repetition by detecting, decoding, and removing other-cell interference in an FDMA or TDMA intra-cell orthogonal system. UCM is a code multiplexing and interference cancellation method for decoding a plurality of signals received with equal power together.

  FIG. 3 schematically shows a UCM transmitter configuration. In the figure, M is the number of users (the number of interference signals), and N is the number of codes multiplexed by UCM (the number of code words in one frame). Here, since the cells are orthogonal to each other and do not cause interference, it is assumed that all users exist in different cells in order to simplify the description.

  Transmission data is serial-parallel converted and encoded by an encoder. The encoded transmission data is multiplied by the amplitude determined for each codeword by the power amplifier and then time-multiplexed by the multiplexer MUX.

In the power amplifier, the k-th code word is multiplied by an amplitude value √a ^(k) (where 0 <k <N−1). The amplitude value calculation unit calculates the amplitude value based on the number of interference signals, the number of codewords in one frame, and noise power.

Next, the interleaver L _m interleaves over N codes, for example, QPSK-modulated, and then OFDM-modulated with pilot symbols to form a transmission signal. FIG. 3 shows an example in which QPSK (Quadrature Phase Shift Keying) is used as the modulation method. Interleaving uses random interleaving having a different pattern for each cell. The pilot symbol is a unique orthogonal code for each cell.

  In the present embodiment, the amplitude value is calculated based on the number of interference signals, the number of codewords in one frame, and noise power (described above). In the above description, the power ratio of the power amplifier is 4: 1, but a specific design method of the power ratio, that is, the amplitude value of each code will be described below.

The amplitude value of each code that enables decoding of all signals is obtained. The transmitter prepares a N code of required SNR i.e. _{E rs / (n 0/2} ) = ρ. Here, E _rs is the signal energy per real number, and n ₀ is the two-sided power spectral density of noise. The energy per real number of the k-th code C ^(k) is set to E _rs ^(k) (E _rs ^(k) > E _rs ^(m) , k> m), and then interleaved over N codes. To send. It is assumed that the signal of M user is received at an equal level at the receiving end.

In addition, since the inside of a cell is orthogonal, interference shall come from another cell. Moreover, the variance of the noise to be added per real number and ^{_{n 0/2 = σ n 2}} . At this time, assuming that the codes from C ^(N-1) to C ^{(k + 1) of} all transmitters have been decoded and canceled, the condition for decoding C ^(k) is expressed by the following equation. The

  Figure 4 shows the decoding process. The number of multiplexed codes for each user is N = 4, and the number of users with the same reception power is M = 3. In the illustrated example, it is assumed that there is no other interference signal having other received power.

The left side of FIG. 4 shows the energy per symbol of each user when a desired wave is deinterleaved. Since the undesired wave has a different pattern of random interleaving from the desired wave, the energy of one interference signal added to the desired signal after deinterleaving is the average of the energy of the codes of all levels. Since there are M-1 undesired signals, all interference energy is obtained by multiplying this energy by M-1, and the energy of E _rs ^(k) is determined by the above equation.

When all the codes have been received by the decoder satisfying energy, code C ⁽³⁾ of all the users with the energy of E _rs ⁽³⁾ is decoded. At this time, the energy of each code when the codes C ⁽³⁾ of all users are canceled is as shown on the right of FIG.

Here, the hatched portion indicates the energy of the canceled signal. It can be seen that since the interference signal code C ⁽³⁾ is also canceled, the energy of the interference signal is reduced. Therefore, the code C ⁽²⁾ having the energy of E _rs ⁽²⁾ can be decoded next, and sequentially decoded from a code having a large SINR.

The minimum E _rs ^(k) that can be decoded by all codes is obtained by solving the recurrence formula using the above equation (1) as an equal sign, and is expressed by the following equation. The amplitude value a ^(k) multiplied by the kth codeword is proportional to E _rs ^(k) .

Consider the worst case where the number of users is M = 2 and the received power of both is the same (because it is easier to decode the interference signal when the received power of the interference signal is large). In this case, it indicates the minimum decodable average E _rs / (n _0/2) with respect to the required E of original codes _rs / (n _0/2) in FIG. As code multiplexing number N is larger average _{E rs / (n 0/2} ) is smaller, the value N = 16 is substantially converged.

Also shows the average _{E rs / (n 0/2} ) when the number of users and M = 3 in FIG. 6. Here, it is assumed that the reception power of all users is equal. Larger average than when the number of users _{M = 2 E rs / (n} 0/2) are required.

A-3. The scope This section decodable reception power in accordance with the transmission signal design method described above, will be explained the range of the received power each code can be decoded.

The number of users M = 2, the required E of original codes _{rs / (n 0/2)} = ρ a 1.0 ₍₀ [dB]), and n 0 /2=1.0 (0 [dB] ). At this time, we are shown respectively in FIGS. 7 to 10 decodable range of the received power when the number of codes N = 1, 2, 4, 8. However, in each figure, the vertical axis represents the average of the desired user _{E rs / (n 0/2} ) [dB], the average horizontal axis of the interference user _{E rs / (n 0/2} ) [dB]. When the code number N is used as a parameter, the range of the power ratio that cannot be decoded is shown by a plot. The difference in the pattern of the plot indicates N symbols.

  When N = 1, that is, when the present invention is not used, as shown in FIG. 7, when the difference between the reception power of the desired user and the interference user is small, decoding is impossible even when the reception power of the desired signal is sufficiently large. It becomes. However, it can be seen from FIGS. 8 to 10 that by using a plurality of codes N and using the present invention, decoding is possible if the received power is sufficiently large even when the powers of both are equal. That is, by increasing the number of code multiplexes, the receivable area is increased and the decoding capability is improved.

A-4. Example of Bit Error Rate Characteristics The results of computer simulation using the amplitude value of a power amplifier designed according to the above design method will be described below. Here, the following assumptions are used.

1. The propagation path is AWGN channel 2. The received SINR of each code is known.
3. The reception timing of each user is the same.
4). Each user has the same received power (ie, worst case for multi-user detection)

  Also, a turbo code using a 3GPP (3rd Generation Partnership Project) permutator is used as the original code. The number of information bits per code was 3456 bits, the coding rate R = 1/2, and the number of repetitions was 20.

FIG. 11 shows the average bit error rate characteristics when the number of equal power users M = 2, that is, the number of interfering users is 1. The horizontal axis in the average of the desired signal _{E rs / (n 0/2} ), the vertical axis represents the average bit error rate of all users, the total code. The number of simulation bits is 10M bits per user per code. In this simulation, interference signal information is taken into account in the decoding process of the turbo code, and the likelihood is calculated using the likelihood information of the code decoded in the previous stage.

As a comparison, the bit error rate characteristics of the original code are illustrated ((M, N) = (1, 1) in the figure). When the required _{E rs / (n 0/2} ) (= ρ) the bit error rate is the smaller value than ^10-6, the From this figure [rho = 1.2 dB. The energy per symbol of each code was calculated from the above equation (2) using this value.

As the code multiplexing number N increases, the energy interval of each code can be made closer. Therefore, the average _{E rs / (n 0/2} ) required to transmit without error is small. The broken line in the figure is the average designed _{E rs / (n 0/2} ). The reason why the simulation value is better than the calculated value is that the accuracy of decoding is improved by using the likelihood information of the previous stage when decoding the turbo code.

B. Second Embodiment In the first embodiment described above, the ratio of amplitude amplification for each frame is changed in accordance with the decoding capability on the receiving station side. For example, the number of interference signals, noise power, and different amplitudes are used. The amplitude value is calculated by the number of codes having the value. Here, since the received power of the interference signal varies, the interference power is set to be the worst value, and the amplitude value of the code is calculated assuming that the power of the interference wave is equal to that of the desired wave. ing.

  However, in an actual propagation path, the power of a plurality of interference waves is rarely equal to that of a desired wave, and there is a problem that transmission power loss occurs in most situations. In addition, since cell arrangement conditions and traffic that is dense and small in terms of location and time are not taken into account, if code design is performed according to a severe situation, transmission power loss occurs in a good situation.

  In an actual cellular system, the cell arrangement method is not uniform, and traffic congestion varies depending on the location and time zone. Therefore, in the second embodiment of the present invention, the status of traffic and the like is monitored at a certain interval, and the number of main interference signals and the number of code words of one frame are changed according to the status, and the above formula (2 ) To update the amplitude value of each code.

  However, when the number of code words in one frame is changed, it is necessary to notify the number of code words to the receiver side. On the other hand, when only the number of interference signals to be considered and the margin of the amplitude value are changed, it is not particularly necessary to notify the receiver of information (amplitude value margin adjustment will be described later).

  FIG. 12 schematically shows a UCM transmitter configuration according to the second embodiment of the present invention. In the figure, M is the number of users (the number of interference signals), and N is the number of codes multiplexed by UCM (the number of code words in one frame). In addition, since the inside of a cell is orthogonal and does not cause interference, it is assumed that all users exist in different cells for the sake of simplicity.

  Transmission data is serial-parallel converted and encoded by an encoder. The encoded transmission data is multiplied by the amplitude determined for each codeword by the power amplifier and then time-multiplexed by the multiplexer MUX.

In the power amplifier, the k-th code word is multiplied by an amplitude value √a ^(k) (where 0 <k <N−1). The amplitude value calculation unit calculates the amplitude value based on the number of interference signals to be considered, the number of code words in one frame, and noise power.

Next, the interleaver L _m interleaves over N codes, for example, QPSK-modulated, and then OFDM-modulated with pilot symbols to form a transmission signal. FIG. 12 shows an example in which QPSK (Quadrature Phase Shift Keying) is used as the modulation method. Interleaving uses random interleaving having a different pattern for each cell. The pilot symbol is a unique orthogonal code for each cell.

  In the present embodiment, the amplitude value is calculated based on the number of interference signals to be considered, the number of code words in one frame, and noise power. Here, the received signal is roughly divided into two signals, a desired signal, an interference signal to be considered, and an interference signal not to be considered according to the magnitude of the received power. The “interference signal to be considered” here is a main interference signal having a large received signal that greatly affects the desired signal.

  FIG. 13 shows the received desired signal and all interference signals in order of power. When calculating the amplitude value, only interference signals exceeding a predetermined threshold value are handled as interference signals to be considered. By limiting the number of interference signals to be considered in this way, the interval of the amplitude ratio is narrowed, and as a result, the transmission power can be further suppressed. In this case, however, there are actually many other interference waves. Here, the power sum of the interference waves not considered as these interference waves is referred to as “residual interference power”. Residual interference power increases noise when viewed from the receiver, and causes degradation of decoding characteristics.

  On the other hand, when the number of interference signals to be considered increases, the average transmission energy increases. In addition, when the number of code words in one frame is increased, the average transmission energy is reduced. However, if the number of codewords is increased, the number of bits per code is reduced, so that the decoding capability is reduced when a turbo code is used.

  In order to control the amplitude value more finely, a margin may be given to the amplitude value. FIG. 14 shows a modification of the transmitter shown in FIG. In the configuration shown in FIG. 12, the amplitude value calculator calculates the amplitude value based on the number of interference signals to be considered, the number of codewords in one frame, and noise power. On the other hand, in the example shown in FIG. 14, the amplitude value calculator further performs a calculation by giving a margin to the amplitude value.

  A method for updating the amplitude value when the decoding characteristic is deteriorated due to an increase in the number of interference signals will be described below with reference to the flowchart shown in FIG.

  First, the state of the propagation path is investigated (the propagation path is always estimated at the time of decoding) (step S1), and the number of interference signals to be considered is determined (step S2).

  Here, when the number of interference signals increases (step S3), the average energy increases, so that the number of codewords per frame is increased to suppress the increase (step S4). However, when the number of code words in one frame is changed, the number of code words is notified to the receiver side (step S5).

  If the number of code words is increased too much, the characteristics of the turbo code deteriorates (step S6), so the margin of the amplitude value is lowered (the difference in amplitude value between code words is reduced) (step S7), and the average energy increases. Do not.

  On the other hand, when the number of interference signals decreases (step S8), the number of codes in one frame is reduced (steps S9 and S10), or the amplitude value is updated by increasing the margin of the amplitude value (step S11). .

  FIG. 16 schematically shows the configuration of the UCM receiver according to the present embodiment. The receiver shown in the figure can receive and process transmission signals from the transmitters shown in FIGS. 12 and 14, and also corresponds to the transmitter according to the first embodiment shown in FIG. The configuration and operation of this receiver will be described below.

  The received signal from each cell is subjected to phase compensation in the channel estimation / compensation unit based on the channel fluctuation estimated from each pilot symbol.

  Thereafter, the signal is deinterleaved through OFDM demodulation and QPSK demodulation. When the deinterleaving of the received signals of all users is completed, the code detection unit selects the codeword having the largest SINR and decodes the code.

  The decoded data is encoded by the re-encoding unit shown in the lower part of the figure, and UCM multiplexed again. Here, symbols that are not decoded at present are multiplexed as zero. Also in OFDM modulation, the pilot symbol is treated as 0, and after taking into account the estimated channel fluctuation, the canceller cancels the received signal. In this way, decoding and cancellation are repeated until all necessary codewords can be decoded.

  The receiver notifies the transmitter of the information when the decoding characteristics change greatly due to traffic fluctuation or increase / decrease in the number of interfering stations. On the transmitter side, the amplitude value of the code is recalculated based on the notification from the receiver, and the code is multiplexed using the new amplitude value. Alternatively, the transmitter may estimate the propagation path condition of the link to be transmitted from the propagation path condition received by the transmitter and recalculate the amplitude value. In the latter case, a special procedure for notifying the propagation path condition from the receiver to the transmitter becomes unnecessary.

  Further, when the transmitter side changes the number of codewords per frame and resets the amplitude value of each codeword, the frame configuration changes, so that information needs to be transmitted to the receiver side. On the other hand, when the number of code words is fixed and the amplitude value of each code is reset according to the number of interference signals to be considered and the margin of the amplitude value, it is not necessary to notify the receiver of that fact.

C. Third Embodiment In the second embodiment of the present invention, a received signal is roughly divided into two signals, a desired signal, an interference signal to be considered and an interference signal not to be considered, according to the magnitude of the received power. Yes. That is, a major interference signal having a large received signal that greatly affects the desired signal is treated as an “interference signal to be considered”, and the amplitude value of each code is calculated based on the number of interference signals to be considered.

  By limiting the number of interference signals to be considered in this way, the interval of the amplitude ratio is narrowed, and as a result, the transmission power can be further suppressed. On the other hand, there are actually many other interference waves. “Residual interference power” that is the sum of the power of interference waves that are not considered as interference waves increases noise when viewed from the receiver and causes degradation of decoding characteristics.

  Therefore, in the third embodiment of the present invention, when calculating the amplitude value of each code, the amplitude value of each code is determined in consideration of the interference power of the entire system including this residual interference power. FIG. 17 schematically shows a UCM transmitter configuration according to the third embodiment of the present invention. In the figure, M is the number of users (the number of interference signals), and N is the number of codes multiplexed by UCM (the number of code words in one frame). In addition, since the inside of a cell is orthogonal and does not cause interference, it is assumed that all users exist in different cells for the sake of simplicity. The configuration and operation of the transmitter shown in FIG.

  Transmission data is serial-parallel converted and encoded by an encoder. The encoded transmission data is multiplied by the amplitude determined for each codeword by the power amplifier and then time-multiplexed by the multiplexer MUX.

In the power amplifier, the k-th code word is multiplied by an amplitude value √a ^(k) (where 0 <k <N−1). The amplitude value calculation unit calculates the amplitude value based on the number of interference signals to be considered, the number of code words in one frame, and noise power.

Next, the interleaver L _m interleaves over N codes, for example, QPSK-modulated, and then OFDM-modulated with pilot symbols to form a transmission signal. FIG. 12 shows an example using QPSK as the modulation method. Interleaving uses random interleaving having a different pattern for each cell. The pilot symbol is a unique orthogonal code for each cell.

  In the present embodiment, the amplitude value calculation unit calculates the amplitude value based on the number of interference signals to be considered, the number of codewords in one frame, and noise power, as well as the amplitude value margin and the average residual interference power. The average residual interference power mentioned here corresponds to the average value of the power for interference signals other than the desired signal and the interference signal to be considered shown in FIG.

  Here, a method of calculating the amplitude value of each code in the amplitude value calculation unit will be described with reference to FIG.

  The number M of interference signals to be considered can be determined based on, for example, the reception power of each user detected in the channel estimation process performed at the time of signal reception. In the example shown in FIG. 13, the number M of interference signals to be taken into consideration is obtained by subtracting the number of desired signals (= 1) from the number of signals exceeding a predetermined threshold.

Further, the assumed noise power n ₀ is basically composed of thermal noise, and therefore does not vary (that is, it is treated as a constant).

The average residual interference power is an average value of the power of the interference signal that is not taken into account, and is used for the amplitude value calculation here by increasing the noise variance σ _n ² .

  The amplitude value margin is determined based on SINR obtained by channel estimation and error characteristics obtained at the time of signal decoding. Here, the margin adjustment of the amplitude value is performed by multiplying the required SNR, that is, ρ by a certain value.

First, noise variance σ _n ² is determined in consideration of the average residual interference power (step S21).

  Next, the required SNR, that is, ρ is determined for adjusting the margin of the amplitude value (step S22).

Then, together with the parameter values obtained in the preceding steps S21 and S22, the number of interference signals M to be considered, the number N of code words in one frame, and the assumed noise power n ₀ are input, and the equation (2) is calculated. The amplitude value of the code is obtained (step S23).

  Note that the receiver shown in FIG. 16 is also compatible with the transmitter according to the third embodiment shown in FIG.

  For example, the base station as a transmitter according to the present embodiment collects information on average residual interference power from each terminal and calculates the amplitude value of each code in consideration of the value. When the average residual interference power is large, there is a possibility that the low-level code is buried in the residual interference and cannot be decoded, so the amplitude of the low-level code is increased. Although the amplitude of the high-level code also increases, the number of interference waves to be considered, the number of codes in one frame, the amplitude value margin, and the like are adjusted in order to maintain the average transmission power.

[Supplement]
The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiment without departing from the gist of the present invention. That is, the present invention has been disclosed in the form of exemplification, and the contents described in the present specification should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims section described at the beginning should be considered.

FIG. 1 is a diagram schematically illustrating a transmission model according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing a configuration of a receiver according to an embodiment of the present invention. FIG. 3 is a diagram schematically showing a UCM transmitter configuration according to an embodiment of the present invention. FIG. 4 is a diagram schematically showing the decoding process. Figure 5 is a diagram showing the minimum decodable average _{E rs / (n 0/2} ) for the original code of the required _{E rs / (n 0/2} ) when the number of users and M = 2. Figure 6 is a diagram showing an average _{E rs / (n 0/2} ) when the number of users and M = 3. FIG. 7 is a diagram showing a range of reception power that can be decoded when the number of code multiplexing N = 1. FIG. 8 is a diagram showing a range of reception power that can be decoded when the number of code multiplexing N = 2. FIG. 9 is a diagram showing a range of received power that can be decoded when the number of code multiplexes N = 4. FIG. 10 is a diagram showing a range of received power that can be decoded when the number of code multiplexes N = 8. FIG. 11 is a diagram showing average bit error rate characteristics when the number of interfering users is 1. FIG. 12 is a diagram schematically showing a UCM transmitter configuration according to the second embodiment of the present invention. FIG. 13 is a diagram for explaining a process for determining the number of interference signals to be considered. FIG. 14 is a diagram schematically showing a modification of the transmitter configuration shown in FIG. FIG. 15 is a flowchart showing a method for updating the amplitude value when the decoding characteristic deteriorates due to an increase in the number of interference signals. FIG. 16 is a diagram schematically illustrating the configuration of a receiver according to an embodiment of the present invention. FIG. 17 is a diagram schematically showing a UCM transmitter configuration according to the third embodiment of the present invention. FIG. 18 is a flowchart for explaining a method of calculating the amplitude value of each code in the amplitude value calculation unit. FIG. 19 is a diagram schematically showing a cell configuration in a mobile radio communication system in which a service area is expanded by a plurality of base stations.

Explanation of symbols

103, 113, 203 ... Encoder X
104, 114, 213 ... encoder Y
107, 205 ... Interleaver A
107, 215 ... Interleaver B
201, 207 ... Deinterleaver A
202, 208 ... Decoder X
211, 217 ... Deinterleaver B
212, 218 ... Decoder Y

Claims (30)

A communication system that increases the capacity by realizing one frequency repetition by a non-spreading method,
Each transmitting station side divides transmission information into a plurality of frames, encodes each frame, power-amplifies each encoded signal with a different amplitude, and bundles each amplified signal to cover all signals. Send the transmission signal obtained by interleaving,
On the receiving station side that receives transmission signals from one or more transmitting stations, the transmission signal from each transmitting station is deinterleaved in accordance with the respective interleaving method, and a signal is transmitted to the deinterleaved transmission signal for each transmitting station. By decoding in order from a code with a large interference-to-interference and noise power ratio to reproduce the original divided frame , and re-encoding the decoded signal , sequentially canceling from the received signal, and repeating deinterleaving and decoding , Get transmission information for each transmitting station,
A communication system characterized by the above. Use different interleaving patterns for each user,
The communication system according to claim 1. Use different interleaving patterns for each cell,
The communication system according to claim 1. On the transmitting station side, change the amplitude amplification ratio for each frame according to the decoding capability on the receiving station side,
The communication system according to claim 1. On the transmitting station side, the code multiplexing number is determined according to the decoding capability or processing capability realized on the receiving station side,
The communication system according to claim 1. On the transmitting station side, the propagation path conditions such as traffic are monitored at certain intervals, and according to the propagation path conditions, the number of interference signals to be considered, the number of code words of one frame, and the noise power of each code Update the amplitude value,
The communication system according to claim 1. On the transmitting station side, when calculating the amplitude value of each code, use the residual interference power consisting of the power sum of the interference waves that were not considered as interference waves,
The communication system according to claim 6. On the transmitting station side, if the average residual interference power is large, increase the amplitude of the low-level code.
The communication system according to claim 7. On the transmitting station side, when the amplitude of the low-level code is increased, the number of interference waves to be considered, the number of codes in one frame, and the amplitude value margin are adjusted to maintain the average transmission power.
The communication system according to claim 8. A transmission device that transmits information by a non-spreading method,
Frame dividing means for dividing the transmission information into a plurality of frames;
Means for encoding each frame;
Power amplifying means for amplifying power by changing the ratio of amplitude amplification for each frame according to the decoding capability on the receiving station side for each encoded signal;
Interleaving means for interleaving the amplified signals together as a group,
A transmission means for transmitting a transmission signal obtained by interleaving;
A transmission device comprising: The frame dividing means determines the number of code multiplexes according to the decoding capability or processing capability realized on the receiving station side,
The transmitter according to claim 10. Providing further a propagation path monitoring means for monitoring a propagation path condition such as traffic at a certain interval,
The power amplifying means updates the amplitude value of each code based on the number of interference signals to be considered, the number of code words in one frame, and noise power according to the propagation path condition.
The transmitter according to claim 10. The power amplifying means uses residual interference power consisting of the power sum of interference waves not considered as interference waves when calculating the amplitude value of each code.
The transmission device according to claim 12, wherein: The power amplifying means increases the amplitude of the low-level code when the average residual interference power is large.
The transmission device according to claim 13. The power amplification means adjusts the number of interference waves to be considered, the number of codes in one frame, and the amplitude value margin when the amplitude of a low-level code is increased, and maintains the average transmission power,
The transmitter according to claim 14. A transmission method for transmitting information in a non-spread mode,
A frame division step for dividing the transmission information into a plurality of frames;
Encoding each frame;
A power amplification step of amplifying each encoded signal by changing the ratio of amplitude amplification for each frame according to the decoding capability on the receiving station side ;
An interleaving step for grouping the amplified signals together and interleaving across all signals;
A transmission step of transmitting a transmission signal obtained by interleaving;
The transmission method characterized by comprising. In the frame division step, the number of code multiplexes is determined according to the decoding capability or processing capability realized on the receiving station side,
The transmission method according to claim 16. A propagation path monitoring step for monitoring a propagation path condition such as traffic at a certain interval;
In the power amplification step, the amplitude value of each code is updated based on the number of interference signals to be considered, the number of codewords in one frame, and the noise power according to the propagation path condition.
The transmission method according to claim 16. In the power amplification step, when calculating the amplitude value of each code, the residual interference power made up of the power sum of the interference waves not considered as interference waves is used.
The transmission method according to claim 18. In the power amplification step, when the average residual interference power is large, the amplitude of the low level code is increased.
The transmission method according to claim 19. In the power amplification step, when the amplitude of the low-level code is increased, the number of interference waves to be considered, the number of codes in one frame, and the margin of the amplitude value are adjusted to maintain the average transmission power.
The transmission method according to claim 20, wherein: A transmission signal obtained by encoding each frame formed by dividing transmission information, power-amplifying each encoded signal with a different amplitude, and interleaving all the amplified signals together. Receiving device from one or more transmitting stations ,
Deinterleaving means for deinterleaving the transmission signal from each transmitting station in accordance with the respective interleaving method ;
Decoding means for sequentially decoding a transmission signal deinterleaved for each transmission station from a code having a large signal-to-interference and noise power ratio to reproduce the original divided frame ;
And a signal cancellation means for re-encoding the decoded signals are sequentially canceled from the received signal,
By repeatedly deinterleaving and decoding the output signal from the signal canceling means, transmission information for each transmitting station is obtained.
A receiving apparatus. A transmission signal obtained by encoding each frame formed by dividing transmission information, power-amplifying each encoded signal with a different amplitude, and interleaving all the amplified signals together. Receiving from one or more transmitting stations ,
A deinterleaving step for deinterleaving the transmission signal from each transmitting station corresponding to each interleaving method ;
A decoding step of sequentially decoding a transmission signal deinterleaved for each transmission station from a code having a large signal-to-interference and noise power ratio to reproduce the original divided frame ;
And a signal cancellation step of re-encoding the decoded signals are sequentially canceled from the received signal,
By repeatedly deinterleaving and decoding the output signal in the signal cancellation step, transmission information for each transmitting station is obtained.
And a receiving method. A code multiplexing method for code multiplexing information to be transmitted by a non-spreading method,
A frame division step for dividing the transmission information into a plurality of frames;
Encoding each frame;
A power amplification step of amplifying each encoded signal by changing the ratio of amplitude amplification for each frame according to the decoding capability on the receiving station side ;
An interleaving step for grouping the amplified signals together and interleaving across all signals;
A code multiplexing method comprising: In the frame division step, the number of code multiplexes is determined according to the decoding capability or processing capability realized on the receiving station side,
25. The code multiplexing method according to claim 24. In the power amplification step, the amplitude value of each code is updated based on the number of interference signals to be considered, the number of codewords in one frame, and the noise power according to the propagation path condition.
25. The code multiplexing method according to claim 24. In the power amplification step, when calculating the amplitude value of each code, the residual interference power made up of the power sum of the interference waves not considered as interference waves is used.
27. The code multiplexing method according to claim 26. In the power amplification step, when the average residual interference power is large, the amplitude of the low level code is increased.
The code multiplexing method according to claim 27. In the power amplification step, when the amplitude of the low-level code is increased, the number of interference waves to be considered, the number of codes in one frame, and the margin of the amplitude value are adjusted to maintain the average transmission power.
The code multiplexing method according to claim 28. One or more obtained by encoding each frame formed by dividing transmission information, power-amplifying each encoded signal with a different amplitude, and interleaving all the amplified signals together. A decoding method for decoding a transmission signal from a transmitting station of
A deinterleaving step for deinterleaving the transmission signal from each transmitting station corresponding to each interleaving method ;
A decoding step of sequentially decoding a transmission signal deinterleaved for each transmission station from a code having a large signal-to-interference and noise power ratio to reproduce the original divided frame ;
A signal cancellation step of re-encoding the decoded signal and sequentially canceling from the received signal;
The decoding method characterized by comprising.

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