JP4683480B2 - Wireless communication system, wireless communication method, and wireless communication apparatus - Google Patents

Abstract

A wireless communication apparatus, a wireless communication method, and a wireless communication system are provided to preventing communication quality from being deteriorated due to a phase shift of Tx data by changing the in-phase component and quadrature-phase component of Tx data each other to create changed data, and transmitting the Tx data and the changed data. A wireless communication apparatus comprises a changing part and a transmitting part. The changing part changes the in-phase component and quadrature-phase component of Tx data each other and creates changed data. The transmitting part transmits the Tx data and the changed data. Also, the wireless communication apparatus comprises a multi-processing part, a receiving part, and a decoded data creation part. The multi-processing part executes code division multiplexing by dividing the Tx data into more than two and multiplying each divided Tx data by a certain code. The receiving part receives the Tx data and the changed data. The decoded data creation part changes the in-phase component and quadrature-phase component of the changed data for each other, combines the changed data with the received Tx data, and creates decoded data.

Description

  The present invention relates to a radio communication system, a radio communication method, and a radio communication apparatus, and is particularly suitable for application to a mobile communication system.

  In recent years, there have been a number of transmission information data repetitive transmission schemes, such as CIBS-CDMA (Chip-Interleaved Block Spread-Code Division Multiple Access) scheme and IMFDA (Interleaved Frequency Division Multiple Access) scheme, which is a basic scheme for repeated transmission of transmission information data. . These have better communication quality than existing multiple access schemes such as DS-CDMA (Direct Sequence-CDMA) scheme in a multi-user environment. Hereinafter, this will be described by taking the CIBS-CDMA system as an example.

  FIG. 12 shows a basic configuration of the transmission side 2 and the reception side 3 in the wireless communication system 1 to which the conventional CIBS-CDMA system is applied. As shown in FIG. 12, the CIBS-CDMA system is characterized in that the transmission side 2 interleaves the spread transmission data and the reception side 3 deinterleaves the reception data. These interleaving and deinterleaving change the order of transmission data and reception data in order to convert multipath user interference caused by multipath into intersymbol interference of each user.

  FIG. 13 conceptually shows the contents of spreading processing and interleaving processing performed on the transmission side 2 of the CIBS-CDMA system. In the CIBS-CDMA system, the transmission side 2 performs error correction coding processing on the transmission data at predetermined intervals, and the symbols (Data # 0, Data # 1, Data # 2,...) Thus obtained are processed. On the other hand, in the spreading unit 4 (FIG. 12), an orthogonal code (for example, OVSF: Orthogonal Variable Spreading Factor code) (# 0 to # SF-1) assigned to the user is a unique orthogonal identifier for the user. Multiply sequentially (diffusion processing).

  In the CIBS-CDMA system, the data of each symbol obtained in this way is arranged in the interleaver 5 (FIG. 12) in which the chips for one symbol are arranged in the direction indicated by “Write in” in the figure, and for each symbol. The chips are sequentially written in the memory so that the chips are arranged in the direction indicated by “Read out” in the figure, and thereafter, a predetermined number of symbols are set as one group, and data is read in units of chips in the direction indicated by “Read out” in the figure for each group. In this way, the data arrangement of the transmission data is exchanged (interleaving process). At this time, such data reading is performed a plurality of times for each group. As a result, the transmission data is repeatedly transmitted.

  Note that the orthogonal code used in the spreading process may be of any sequence as long as the complete orthogonality between the orthogonal codes is satisfied. In FIG. 13, GI indicates a guard interval for reducing interference between groups. Such a guard interval is inserted at one group interval.

  On the other hand, on the receiving side 3, as shown in FIG. 12, the deinterleave processing unit 6 arranges the orthogonal codes of the symbols in the direction indicated by “Read out” in the figure for the received data, and the data of each symbol is shown in FIG. The data is sequentially written in the memory so as to be aligned in the direction indicated by “Write in”, and thereafter, a predetermined number of symbols are set as one group, and data is read in the direction indicated by “Read out” in the figure in units of orthogonal codes for each group. Then, the data sequence of the received data is replaced with the original data before interleaving (deinterleaving processing). On the receiving side 3, the despreading processing unit 7 performs despreading processing on the received data in the original data sequence obtained in this way.

According to such a CIBS-CDMA system, for example, as shown in FIG. 14 in which parts corresponding to those in FIG. 12 are assigned the same reference numerals, a result of adding a direct wave (amplitude h1) and a reflected wave (amplitude h2). , D 0, D 1, D 2,... Becomes the symbols X 1, X 2, X 3,..., And intersymbol interference occurs, but the code sequences C 10, C 11, C 12,. Therefore, there is an advantage that the orthogonality between orthogonal codes is satisfied, that is, there is no inter-user interference even in a multipath environment (see Patent Document 1). FIG. 14 shows a state where the reflected wave is delayed by one chip with respect to the direct wave. FIG. 15 shows how orthogonality between orthogonal codes is satisfied even in a multiuser environment.
Special Table 2002-516519

  However, according to the conventional CIBS-CDMA system, there is a problem that the conventional CIBS-CDMA system is easily affected by time fluctuation of the transmission path. This is because the transmission data is interleaved on the transmission side and the reception data is deinterleaved on the reception side. In principle, the time interval between the columns in the deinterleaver is extended. This is because the fluctuation is reflected more greatly than the actual fluctuation. This is shown in FIG.

  The CIBS-CDMA system will be described as an example in more detail. In the CIBS-CDMA system, orthogonality between users is obtained by orthogonal codes. Considering a 2-user environment, a case where a 4-chip orthogonal code is assigned, in which user # 1 is +1, +1, +1, +1, and user # 2 is +1, +1, -1, -1, Assume (a chip indicates one bit of code). In this case, the reception side multiplies the reception signal by the orthogonal code of each user, integrates the 4-chip section, and obtains transmission information of each user. Obviously, the difference in sign between the users # 1 and # 2 is the polarity of the third and fourth chips. If the polarities of the third and fourth chips change, it is impossible to distinguish between users, that is, interference occurs between users (even if the first and second chips change).

  In the above assumption, as shown in FIG. 16, it is assumed that the time variation of the transmission path occurs such that the depth of the interleaver is 90 degrees, that is, a quarter cycle (in other words, one cycle is obtained when four rows are transmitted). Fluctuation). In this case, the order is changed by the deinterleaving process on the receiving side, and the signal sent to the despreading unit becomes a signal that changes 90 degrees for each chip. That is, a fast phase change occurs. As a result, after the third chip, since the phase change exceeding 180 degrees has already occurred, the polarity inversion occurs. Since the transmission path is independent for each user, this state no longer indicates that each user can be identified, that is, cannot communicate.

  In this example, high-speed fluctuations are assumed to help understanding, but in actual operation, high-speed fluctuations do not occur so far. However, the problem that the time interval is compressed by the interleaver / deinterleaver processing in principle and the transmission path time fluctuation becomes high speed remains unchanged.

  As described above, even in the CIBS-CDMA system and IFDMA system in which multi-user interference does not occur, the orthogonality between users is lost due to the above time fluctuation (also referred to as Doppler Spread), and the communication quality deteriorates. It was thought that it was not suitable for practical operation. When a computer simulation is actually performed, it is concluded that communication is impossible in a high-speed moving environment such as a Shinkansen traveling at a speed of 300 km / h (see FIG. 17).

In FIG. 17, since the number of users is 16 with respect to the spreading factor 16, it is in a state of the maximum capacity (Full-Load) generally called. The transmission path assumes a state where there is only one echo, and assumes an uplink (transmission from a mobile station to a base station) in which all users are asynchronous. From the figure, up to 150 km / h, if 2-branch reception diversity can be applied, the target of 4 × 10 ⁻² or less, which can achieve an error rate improvement effect by introducing an error correction code, can be achieved. Thus, it can be seen that it cannot be achieved at a traveling speed of 300 [km / h].

  The present invention has been made in view of the above points, and intends to propose a radio communication system, a radio communication method, and a radio communication apparatus that can improve communication quality by reducing inter-user interference due to phase fluctuations. .

  In order to solve such a problem, in the present invention, in a wireless communication method for transmitting and receiving information signals by performing spread modulation processing between a plurality of wireless communication devices, the transmission side of each wireless communication device performs spread modulation processing on the information signals. After repeatedly transmitting the same transmission data as the obtained transmission data at least twice, the in-phase and quadrature components orthogonal to each other in the transmission data are exchanged at a preset period when retransmitting, On the receiving side, for transmission data transmitted from the transmitting side, after replacing the in-phase and quadrature components in the same period as the set period, the received data in which the in-phase and quadrature components are replaced, and the in-phase and quadrature components Is added to the received data that was not replaced.

  As a result, according to this radio communication system, the reception data in which the in-phase and quadrature components orthogonal to each other are exchanged on the receiving side is changed with respect to the odd-numbered signal that does not perform in-phase and quadrature component exchange The phase fluctuation due to the reverse rotation. That is, the signal vector of the normal odd-numbered received data that does not perform the in-phase and quadrature component replacement that are orthogonal to each other, and the signal vector of the even-numbered received data that has been subjected to the replacement, with respect to the original vector direction, The rotation is in the opposite direction, and the phase fluctuation can be canceled by calculating the sum of these vectors.

  In the present invention, the receiving side compensates for phase fluctuations that occur between the transmission path or the transmitter / receiver for transmission data transmitted from the transmitting side. As a result, according to this wireless communication system, in addition to being able to cancel the phase fluctuation by converting the phase fluctuation into the amplitude fluctuation as described above, the phase fluctuation is compensated for, so When the second and odd-numbered vectors are opposite to each other, it is possible to avoid that the phase angle becomes too large and the level drop becomes significant.

  Further, in the present invention, on the transmission side, transmission data obtained by performing spread modulation processing on the information signal is subjected to code division multiplexing processing to compensate so that the number of information included in the transmission data is at least halved. As a result, according to this wireless communication method, even in a state where a level drop may occur due to the initial phase or phase fluctuation, the level drop is suppressed to a minimum, and the remaining phase fluctuation is replaced with the in-phase and quadrature components orthogonal to each other It can be removed by processing.

  According to the present invention, it is possible to realize a wireless communication system, a wireless communication method, and a wireless communication apparatus that can suppress communication quality deterioration due to phase variation of a transmission path and improve communication quality. This makes it possible to reduce the required transmission power required for radio waves to reach the receiving side in order to achieve a certain predetermined communication quality, and it is also possible to save power as the entire system.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
(1) First Embodiment (1-1) Radio Communication System According to this Embodiment FIG. 1 shows the basics of a transmission side 11 and a reception side 12 of a radio communication system 10 in which the present invention is applied to a CIBS-CDMA system. The configuration is shown. One of the features of the CIBS-CDMA system according to the present embodiment in comparison with the above-described conventional CIBS-CDMA wireless communication system 1 (FIG. 12) is that the transmission side 11 performs I (Inphase: In-phase), Q (Quadrature-phase: orthogonal) plane I and Q component switching processing (hereinafter referred to as IQ switching processing) is performed, and the receiving side 12 also performs IQ switching processing on the received data. This is executed, and thereafter, addition processing is performed.

のように表される。The meaning of executing the IQ replacement process is its phase fluctuation. Hereinafter, it is expressed by a mathematical formula. If a transmission complex signal that changes in a T time period (T is a symbol time, for example, T = 16t) is X (t), X (t) is expressed by the following equation:

It is expressed as

とも表現できる。（１）式及び（２）式は、表現方法が異なるだけで、全く同じである。ここで、｜｜は絶対値記号、｜α（ｔ）｜は振幅 （＝√（Ｉ２＋Ｑ２））、θ（ｔ）は、送信情報によって変化する角度情報（ｅ．ｇ．，ａｔａｎ（Ｑ，Ｉ））である。Here, I _tx (t) is an in-phase component of transmission information, and Q _tx (t) is a quadrature component of transmission information. This equation (1) is expressed as follows using an exponential expression:

Can also be expressed. Expressions (1) and (2) are exactly the same except for the expression method. Here, || is an absolute value symbol, | α (t) | is amplitude (= √ (I2 + Q2)), and θ (t) is angle information (eg, atan (Q, I) that varies depending on transmission information. )).

のように変化する。ここで、ＩＳＭ（）とは、ＩＱ入れ替え処理を示す関数である。（３）式を（１）式に近づける様に変形すると、次式、

と表現できる。指数表現をすれば、次式、

と表現できる。（５）式より、ＩＱ入れ替え処理というのは、入れ替えを実行しない信号に対して、９０度の位相シフト（＝ｊの乗算）と、位相角の進行方向が逆回転になることを意味することがわかる。Here, the I and Q signals are exchanged. Formula (1) is the following formula:

It changes as follows. Here, ISM () is a function indicating IQ replacement processing. When the equation (3) is modified so as to be close to the equation (1), the following equation:

Can be expressed as In exponential terms,

Can be expressed as From equation (5), the IQ replacement process means that the phase shift of 90 degrees (= multiplication of j) and the traveling direction of the phase angle are reversed with respect to a signal that is not subjected to replacement. I understand.

となる。この信号を受信し、受信機側でもＩＱ入れ替え処理を行うと、ＩＱ入れ替え処理であるＩＳＭ（）関数は、ｊの位相シフトと、位相回転方向の逆転であったため、次式、

のようになる。この（６）式が意味するのは、ＩＱ入れ替え処理が実行されない送信情報が復元できると同時に、伝送路位相シフトが逆方向となっていることである。Next, a phase variation term due to a phase change between the transmission line or the transceiver is added. In the exponential expression, the phase fluctuation can be expressed by multiplication. Therefore, if the phase fluctuation is θch (t), the received signal y (t) affected by this is expressed by the following equation:

It becomes. When this signal is received and the IQ exchange process is performed on the receiver side, the ISM () function that is the IQ exchange process is a phase shift of j and a reversal of the phase rotation direction.

become that way. This equation (6) means that transmission information that is not subjected to IQ replacement processing can be restored, and at the same time, the transmission path phase shift is in the reverse direction.

のようになる。As a result, when the sum of the signal that has undergone IQ replacement processing and the signal that has not been implemented is obtained,

become that way.

Here, α (t) and θ (t) indicating the transmission information signal are both before T time has elapsed. Therefore, it does not change at the time of y (t) and y (t + 1), and can be regarded as the same. Further, if it is a minute time, it is considered that θ _ch (t) and θ _ch (t + 1) do not substantially change, the imaginary component is canceled out, and the result of equation (8) is obtained. From the equation (8), it can be seen that the sum of what is executed and what is not executed is projected onto the real axis, the phase fluctuation term disappears, and only the amplitude fluctuation occurs. The above situation is illustrated as shown in FIG.

This result shows that it is possible to avoid the change in polarity that occurs in the user identifier (= orthogonal code) due to the phase fluctuation described in the problem of the prior art. In the equation (8), although amplitude fluctuation remains, it is not complete inter-user orthogonal signal processing, but a great effect is produced by the wireless communication access method such as CIBS-CDMA and IFDMA.
In the equation (8), the correspondence when the initial phase term occurs will be described later in the description of claim 2.

  An object of the present invention is to improve inter-user orthogonality in a multi-user environment in the access method such as CIBS, IFDMA, or a modification thereof. Unlike the conventional DS-CDMA (the third generation mobile communication system called FOMA and cdmaWIN (both are trade names)), these access systems based on CDMA aim at perfect orthogonality between users. When aiming at perfect orthogonality between users, it is incomplete to perform phase compensation by signal processing after user signal extraction (= despreading processing) as in conventional DS-CDMA, and an identifier between users before user signal extraction. The perfect orthogonality of (orthogonal code for CIBS-CDMA, orthogonal frequency for IFDMA) must be satisfied.

のように表される。In this case, it is necessary to compensate for the phase variation of the transmission path and the phase variation between the transmitter and receiver before the despreading process. As a compensation means for phase fluctuation before user extraction, a method called delay detection is generally used. As an example, in delay detection, conjugate complex multiplication with a signal one symbol before is generally performed, and phase fluctuations in the transmission path are reduced. This will be described below using mathematical formulas. If the received signal is s (t), s (t + 1), the delayed detection signal is

It is expressed as

理を行い、差分に送信情報を載せることとする。（９）式から明らかな様に、伝送路の位相変動が消失もしくは、低減される。この利点から、第２世代の移動通信では、遅延検波が一般的に使用されていた。

The transmission information is put on the difference. As is clear from the equation (9), the phase variation of the transmission path disappears or is reduced. Because of this advantage, delay detection is generally used in second-generation mobile communications.

  However, there is a problem with this delayed detection. First, it is difficult to apply the multi-level modulation technique, and the characteristic deterioration is remarkable. As is clear from the equation (9), since transmission information is given to the phase term, in the multilevel modulation technique in which information is also present in the amplitude called 16QAM, there is a remarkable characteristic deterioration.

のようにＮユーザ環境に適用すると、容易にわかるように、共役複素乗算の際に、クロスタームが発生し、雑音とみなせる信号が増大してしまう。As a next problem, since delay detection basically assumes a one-user environment, there is a problem in application before user extraction. S (t) in the equation (9) is expressed by the following equation:

When applied to an N user environment as described above, as can be easily understood, a cross term is generated during conjugate complex multiplication, and the number of signals that can be regarded as noise increases.

  From the above results, delayed detection cannot be applied to inter-user orthogonalization before despreading, and phase compensation means has not existed so far.

  However, according to the CIBS-CDMA system according to the present embodiment, even when a phase variation occurs in the ideal reception signal (= transmission signal) (FIG. 3A) (FIG. 3B), FIG. Thus, by substituting with amplitude fluctuation, orthogonalization between users can be assisted.

  Further, as apparent from the equation (8), the amplitude term | α (t) | can be arbitrarily applied, so that it can also be applied to the 16QAM transmission with amplitude variation described above. 16QAM modulation is indispensable in next-generation high-speed mobile communication (= increase in the amount of bit transmission per unit time is required), and this multi-level modulation can be applied before user extraction while phase fluctuation can be suppressed. The effect to say is very large.

(1-2) Radio Communication System According to this Embodiment Next, a specific configuration of a radio communication system to which the CIBS-CDMA scheme according to this embodiment is applied will be described. In this description, in order to help understanding, it is assumed that the execution timing of the IQ replacement process is obtained by an instruction from a higher-order management station described later. However, this is only an example and is unique between the transceivers. If it is decided, it is unnecessary.

  FIG. 5 shows a radio communication system according to the present embodiment. The wireless communication system 20 includes a plurality of mobile communication devices 21 (10) or a plurality of base stations 22 and a host control station 23.

  The mobile communication device 21 is configured as shown in FIG. 6, collects the user's uttered voice by the microphone 30, and inputs the obtained voice signal S 1 to the signal processing unit 31. The signal processing unit 31 performs predetermined signal processing such as analog / digital conversion on the supplied audio signal S1, and then inputs this to the QPSK modulation unit 32 as a digital audio signal S2. Further, the QPSK modulation unit 32 QPSK modulates the supplied digital audio signal S2 and sends the obtained QPSK modulation signal S3 to the diffusion processing unit 33.

  At this time, the orthogonal code generation unit 34 is provided with the spreading factor SF designated by the higher control station 23 (FIG. 5) and the code number of the orthogonal code assigned to the user from the transmission / reception unit 39 as the orthogonal code designation information D1. . Then, the orthogonal code generation unit 34 generates a corresponding orthogonal code having a corresponding spreading factor SF based on the orthogonal code designation information D 1, and sends this to the spreading processing unit 33.

  Thus, the spread processing unit 33 spreads the QPSK modulation signal S2 by multiplying the orthogonal code and the QPSK modulation signal S3, and sends the obtained spread processing signal S4 to the IQ exchange processing unit 35. Further, the IQ exchange processing unit 35 performs the IQ exchange process described above with reference to FIG. 1 on the supplied spread signal S4, and sends the obtained signal S5 to the interleaver 36.

  At this time, the IQ exchange instruction unit 37 is provided from the transmission / reception unit 39 as IQ exchange timing designation information D2 designated by the host control station 23 (FIG. 5). Then, the IQ exchange instruction unit 37 repeatedly generates the designated timing in synchronization with the spread processing signal S5 based on the IQ exchange timing designation information D2, and sends these to the IQ exchange processing unit 35.

  Thus, the IQ exchange processing unit 35 executes the IQ exchange process at the timing given from the IQ exchange instruction unit 37 on the spread signal S4 given from the diffusion processing unit 33 under the control of the transmission / reception unit 39, for example. To do. Then, the IQ exchange processing unit 35 sends the obtained exchange signal S5 to the interleaver 36. In the interleaver 36, the time relationship between the spread signal and the signal to be transmitted is changed according to a predetermined rule and transmitted to the guard interval insertion unit 38, as in the conventional technique.

  The guard interval insertion unit 38 sequentially inserts guard intervals for every predetermined symbol of the scramble signal S6, and sends the obtained GI insertion scramble signal S7 to the transmission / reception unit 39. Further, the transmission / reception unit 39 performs predetermined signal processing such as predetermined filter processing for limiting the band and up-conversion processing for increasing the frequency of the GI insertion scramble signal S7 on the GI insertion signal S7, and thus obtained. The transmission signal S8 is transmitted through the antenna 40.

  On the other hand, in the mobile communication device 21 (FIG. 5), the transmission / reception unit 39 receives the transmission signal S10 transmitted from the call partner side through the base station 22 via the antenna 40. Then, the transmission / reception unit 39 performs predetermined signal processing such as down-conversion processing on the transmission signal S10 and transmits the obtained reception signal S11 to the guard interval removal unit 41.

  In addition to this, the transmission / reception unit 39 transmits the orthogonal code designation information D1 transmitted from the higher control station 23 via the base station 22 to the orthogonal code generation unit 34, and from the higher control station 23 to the base station. The above-described IQ replacement timing designation information D2 transmitted via the transmission terminal 22 is transmitted to the IQ replacement instruction unit 37.

  The guard interval removing unit 41 removes the guard interval from the given reception signal S11 and sends the obtained GI removal reception signal S13 to the deinterleaver 43. The deinterleaver 43 deinterleaves the supplied interleave signal S13 as described above with reference to FIG. 1, and sends the obtained deinterleave signal S14 to the IQ exchange decoding processing unit 45.

  The IQ exchange instruction unit 44 repeatedly generates an IQ exchange instruction signal at a designated time based on the IQ exchange execution timing designation information D2 given from the transmission / reception unit 39 as described above, and generates the IQ exchange instruction processing unit 45. To send.

  Thus, for example, under the control of the transmission / reception unit 39, the IQ replacement decoding processing unit 45 converts the signal S14 supplied from the deinterleaver 43 to the deinterleave signal S14 at the timing supplied from the IQ replacement instruction unit 44. Perform replacement decoding. The IQ replacement decoding process is, for example, adding the even-numbered and odd-numbered signals after performing the same IQ replacement process on the transmission side as described in detail in FIG. It is. After these processes, the IQ replacement decoding processor 45 sends the decoded signal S15 obtained as a result to the despreading processor 46.

  At this time, the orthogonal code generation unit 47 generates an orthogonal code assigned to the user based on the orthogonal code designation information D1 given from the transmission / reception unit 39 as described above, and sends this to the despreading processing unit 46. . Thus, the despreading processing unit 46 despreads the spread signal S15 by multiplying the spread code S15 by the orthogonal code given from the orthogonal code generation unit 47, and the obtained QPSK modulation signal S16 is subjected to the QPSK demodulation unit. 48.

  The QPSK demodulator 48 performs a QPSK decoding process on the supplied QPSK modulation signal S16 and sends the obtained digital audio signal S17 to the signal processor 49. Further, the signal processing unit 49 performs predetermined signal processing such as digital / analog conversion processing on the supplied digital audio signal S17, and sends the obtained audio signal S18 to the speaker 50. As a result, sound based on the sound signal S18 is output from the speaker 50.

  In this way, in the mobile communication device 21, the user's voice is transmitted to the call partner side, while the sound transmitted from the call partner side can be output from the speaker 50.

  On the other hand, FIG. 7 shows a configuration of a communication control device 60 provided in the upper control station 23 (FIG. 5) for controlling communication between the mobile communication devices 21. As is apparent from FIG. 7, the communication control device 60 includes a CPU (Central Processing Unit) 61 that controls the operation of the entire communication control device 60, and a ROM (Read Only Memory) 62 in which various control programs are stored. A RAM (Random Access Memory) 63 as a work memory of the CPU 61, a storage device 64 such as a flash ROM storing various application software, and the CPU 61 connected to each base station 22 (FIG. 5) with a telephone line or a wireless communication line. The communication processing unit 65 as an interface for performing communication via the network is connected to each other via a bus 66.

(1-3) Operation and effect of the present embodiment In the above configuration, the transmission side performs IQ exchange processing and transmits, and the reception side executes IQ exchange processing and adds them.

  According to such a wireless communication system, the phase fluctuation under the phase fluctuation environment can be eliminated by calculating the sum of the signal that has been subjected to the IQ replacement process and the signal that has not been executed on the receiving side. As a result, it becomes possible to replace the phase fluctuation with respect to the spread code (= realized by ± 1), which is the user identifier, with the amplitude fluctuation, thereby improving the orthogonality between users.

  Therefore, by applying the wireless communication system according to the present embodiment, phase fluctuation that is a weak point of the CIBS-CDMA system can be reduced, so that the communication quality can be improved as compared with the conventional wireless communication system. .

  And by improving communication quality in this way, it becomes possible to reduce the required transmission power required until the radio wave reaches the receiving side. This means that if the mobile communication device 21 considers the uplink to the base station 22, it means that the battery of the mobile communication device 21 is allowed to last for a long time, and if it is considered on the downlink, the power saving of the infrastructure equipment can be achieved. means. In addition, if the application does not particularly require power saving, it means that the radio wave reach is extended, that is, the service area is expanded, and in any case, an effective effect can be obtained.

(2) Second embodiment (2-1) Wireless communication system according to this embodiment In the first embodiment, the present invention is an environment in which the initial phase is not considered or the phase change is not severe. The case where it applies to was explained. When the phase change is severe, the configuration of the present invention causes a decrease in the amplitude level, and the improvement effect is reduced. However, even in this case, it is possible to prevent deterioration by effectively arranging general phase compensation means. In the second embodiment, an effective implementation example of the present invention is disclosed.

  FIG. 8, in which parts corresponding to those in FIG. 6 are assigned the same reference numerals, shows a mobile communication device 70 according to the second embodiment of the present invention. As is apparent from FIG. 8, a different part is the presence of a frequency domain equalization unit (FDE: Frequency-domain equalization) 71. The frequency domain equalization unit 71 compensates for amplitude / phase fluctuations occurring in the transmission path in the frequency domain. This is an existing technology that is effective in a multipath environment.

  The frequency domain equalization unit 71 performs a predetermined frequency domain equalization based on a minimum mean square error (MMSE) standard for improving the bit error rate characteristics of the supplied GI-removed reception signal S12. Processing is performed, and the obtained equalized signal S13 is sent to the dintariba 43. Generally, a compensation coefficient specialized for the user's transmission path to be extracted is given. Therefore, in base station reception in which a plurality of users are added and input, although the amplitude / phase compensation of the target user can be performed, a coefficient completely unrelated to other users is given, so the amplitude / phase of other users are warped and disturbed. Is done.

  As described above, in the present invention, the amplitude change occurs according to the phase fluctuation amount. Therefore, the amplitude level of the other user signal given a large phase fluctuation by the frequency domain equalization unit 71 is reduced. Reducing the amplitude means that the influence on the target user is reduced. Since the phase change is a random variable, it cannot be stated that the amplitude level is always reduced. However, since the present invention always reduces the level when the phase change occurs, the amount of interference by other users is worst when the present invention is not used. The communication quality is always better than that.

  On the other hand, for the target user, the frequency domain equalization unit 71 acts to perform multipath compensation and also phase compensation. That is, the signal of the target user after passing through the frequency domain equalization unit 71 is a signal in which the initial phase and the phase fluctuation are compensated to some extent. As a result, when the present invention is applied, it is possible to compensate for a residual phase change that could not be compensated by the FDE.

  As described above, when applying the present invention, in the reception process, it is desirable to perform phase compensation (preferably also amplitude compensation) before the IQ replacement decoding processing unit 45. In the above example, the frequency domain equalizer 71 is shown. However, any phase compensation technique that satisfies the present description may be used. For example, a conventional time domain equalizer may be used. .

(2-2) Configuration of Radio Communication System According to this Embodiment FIG. 8 shows a radio communication system according to the second embodiment. This radio communication system is configured in the same manner as the radio communication system according to the first embodiment, except that the frequency domain equalizer 71 described above is applied as a transmission path fluctuation compensation method.

  FIG. 8, which shows parts corresponding to those in FIG. 6 assigned the same reference numerals, shows a specific configuration of the mobile communication device in the wireless communication system according to this embodiment. As apparent from FIG. 8, the difference from FIG. 6 is in the receiving system. In the reception system, the reception signal in the radio band received from the antenna 40 is down-converted to the baseband by the transmission / reception unit 39 and sent to the guard interval removal unit 41.

  The guard interval removing unit 41 removes the guard interval from the given received signal S11 and sends the obtained GI removed received signal S12 to the frequency domain equalizing unit (FDE) 71.

  The frequency domain equalization unit 72 performs a predetermined frequency domain equalization process based on the minimum mean square error (MMSE) standard for improving the bit error rate characteristics on the supplied GI removal received signal S12, The scrambled signal S13 is sent to the deinterleaver 43.

  The deinterleaver 43 performs deinterleaving processing uniquely determined by the wireless communication system (in transmission and reception) on the signal S13 subjected to frequency equalization processing, and IQ replacement decoding is performed on the obtained deinterleave signal S14. The data is sent to the processing unit 45.

  In the IQ replacement decoding processing unit 45, the timing at which the IQ replacement processing is executed is specified by the IQ replacement instruction unit 44, and the IQ signal of the received signal S14 is transmitted at the specified timing, as in the first embodiment. Replace.

  Thereafter, the signal S15 obtained by calculating the sum of the signal that has not been subjected to the IQ replacement process and the signal that has been subjected to the IQ replacement process is sent to the despreading processing unit 46.

  At this time, the orthogonal code generation unit 47 generates an orthogonal code assigned to the user based on the orthogonal code designation information D1 given from the transmission / reception unit 39 as described above, and sends this to the despreading processing unit 46. . Thus, the despreading processing unit 46 despreads the spread signal S15 by multiplying the spread code S15 by the orthogonal code given from the orthogonal code generation unit 47, and the obtained QPSK modulation signal S16 is subjected to the QPSK demodulation unit. 48.

  The QPSK demodulator 48 performs a QPSK decoding process on the supplied QPSK modulation signal S16 and sends the obtained digital audio signal S17 to the signal processor 49. Further, the signal processing unit 49 performs predetermined signal processing such as digital / analog conversion processing on the supplied digital audio signal S17, and sends the obtained audio signal S18 to the speaker 50. As a result, sound based on the sound signal S18 is output from the speaker 50.

  In this way, in the mobile communication device 70, the user's voice is transmitted to the call partner side, while the sound transmitted from the call partner side can be output from the speaker 50.

  Here, FIG. 7 shows a configuration of a communication control device 80 provided in the upper control station 22 (FIG. 5) for controlling communication between the mobile communication devices 21. The communication control device 80 is configured similarly to the communication control device 60 according to the first embodiment.

(2-3) Operation and effect of the present embodiment In the above configuration, this wireless communication system also performs IQ replacement processing at a predetermined timing on the transmission side, and also performs IQ replacement at the same timing on the reception side. The process is executed, and the sum of the signal that has been exchanged and the signal that has not been exchanged is calculated.

  However, there is a frequency domain equalizer (FDE) 71 that corrects phase fluctuations between transmission lines or transmitters / receivers before the IQ exchange process on the receiving side is executed. This frequency domain equalizer corrects the phase fluctuation (and amplitude fluctuation) of the user to be extracted, and this correction can minimize the amplitude attenuation caused by the IQ replacement process. Further, the residual phase fluctuation that is not compensated for by the frequency domain equalizer 71 is compensated for phase by phase-amplitude conversion by IQ replacement processing. Furthermore, the phase fluctuation given to the other users by the frequency domain equalizer 71 is reduced in amplitude by the IQ replacement process, and can contribute to the reduction of the other user interference amount.

  Therefore, by applying the wireless communication system according to the present embodiment, phase fluctuation can be reduced, which is a weak point of the CIBS-CDMA system, so that the communication quality can be improved over the conventional wireless communication system. .

FIG. 9 shows the results of evaluating the second embodiment of the present invention by computer simulation. FIG. 9 is a comparison between CIBS-CDMA in the prior art and CIBS-CDMA in which the second embodiment of the present invention is implemented. Obviously, 4 × 10 ^−2, which is an indication of the communication quality regarded as a problem in the prior art, has been achieved, and communication is possible by using an error correction code together, and the effect can be confirmed.

  By improving the communication quality in this way, it is possible to reduce the required transmission power required until the radio wave reaches the receiving side. This means that the battery of the mobile communication device 21 is allowed to last for a long time when considering the uplink from the mobile communication device 21 to the base station 22, and that the power consumption of the infrastructure equipment can be reduced when considering the downlink. means. Further, if the application does not particularly require power saving, it means that the radio wave reach is extended accordingly, and in any case, an effective effect can be obtained.

(3) Third Embodiment In the first and second embodiments described above, the number of transmission information bits per unit time is reduced by transmitting the same signal. This is supplemented by the third embodiment of the present invention.

  An image of the third embodiment of the present invention is shown in FIG. Here, Fig.10 (a)-(c) has shown an example of the functional concept of the transmission side interleaver. FIG. 10A shows an execution image of IQ replacement processing in the first or second embodiment of the present invention. FIG. 10B shows an approach from another concept in which execution of IQ replacement processing is applied in the spreading code direction. In FIG. 10 (c), it is assumed that the signals to be multiplexed are distinguished from each other.

  For example, for transmission data D0 to D3, +1 and +1, and for D4 to D7, +1 and -1. If the first D0 to D3 (or D4 to D7) are grouped together, there are two types of transmission blocks. Therefore, +1, +1 (or +1, -1) is assigned to each block. On the receiving side, despreading is performed using these codes. In FIG. 10 (c), it is shown to help understanding, and since the actual signals are supplied to the interleaver in the added state, D0 to D3 and D4 to D7 are included in the interleaver. A distinction cannot be made.

  FIG. 11 in which the same reference numerals are assigned to the parts corresponding to FIG. 1 shows an example of the configuration of the wireless communication system 90 according to claim 3 of the present invention. The difference from FIG. 1 is that a device for compensating for the fact that the transmission information bits by IQ exchange processing are halved is made. Hereinafter, a description will be given in comparison with FIG.

  In FIG. 1, since the information signal “Data” to be transmitted is halved compared to CIBS-CDMA of the prior art, FIG. 11 shows Data # 1 and Data # 2 in the transmission side 91. Assuming that the data amount in CIBS-CDMA of the prior art is 1, the data amount in FIG. 1 is 0.5, and Data # 1 and Data # 2 in FIG. 11 are also 0.5, respectively. Therefore, in FIG. 11, the same amount of transmission information as that in the prior art is transmitted.

  On the transmission side 91, since the spreading units 93A and 93B are user identifiers, Data # 1 and Data # 2 are multiplied by the same spreading code. After that, code multiplexing is performed in order to distinguish between Data # 1 and Data # 2. Here, the adders 94A and 94B perform code multiplexing, which is equivalent to multiplying by +1 and multiplying by −1 depending on whether the input to the adders 94A and 94B is “+” or “−”. ing. Therefore, FIG. 11 shows an example in which Data # 2 is spread with codes of +1 and -1, and Data # 1 is spread with codes of +1 and +1. These spread signals are added by adders 94A and 94B, and one of them is subjected to IQ replacement by an IQ replacement processing unit 95. Since the operation from the interleaver 96 to the deinterleaver 97 in the receiving side 92 is the same as that in the first and second aspects, it is omitted.

  The output of the deinterleaver 97 is different depending on whether the IQ exchange process is performed or not. This is because each of Data # 1 and Data # 2 is multiplied by a spreading code. The despreading process is performed by the adders 98A and 98B. As with the adder on the transmission side, the subtraction and addition are effectively rearranged to make it equivalent to multiplication by −1 and +1. By the above method, transmission data can be halved.

  The present invention can be applied to a mobile communication system such as a mobile phone system.

It is a block diagram with which it uses for description of the radio | wireless communication system by 1st Embodiment. It is a conceptual diagram with which it uses for description of IQ replacement | exchange process in the CIBS-CDMA system by this Embodiment. It is a constellation diagram showing a state in which a phase variation occurs in a received signal in the conventional CIBS-CDMA system. It is a constellation figure showing the state after IQ replacement | exchange process in the CIBS-CDMA system by this Embodiment. It is a basic diagram which shows schematic structure of the radio | wireless communications system by this Embodiment. It is a block diagram which shows the structure of the mobile telephone apparatus by 1st Embodiment. It is a block diagram which shows schematic structure of a communication control apparatus. It is a block diagram which shows the structure of the mobile telephone apparatus by 2nd Embodiment. It is a chart showing the evaluation result by the computer simulation in 2nd Embodiment. It is a conceptual diagram with which it uses for functional description of the transmission side interleaver by this Embodiment. It is a block diagram with which it uses for description of the radio | wireless communication system by 3rd Embodiment. It is a block diagram with which it uses for the outline | summary structure of the conventional wireless communication system of CIBS-CDMA system. It is a conceptual diagram which shows notionally the content of the spreading | diffusion process and interleaving process performed in the transmission side of the conventional CIBS-CDMA system. It is a conceptual diagram with which it uses for description of the multiuser interference in the conventional CIBS-CDMA system. It is a conceptual diagram with which it uses for description of the multiuser interference in the conventional CIBS-CDMA system. It is a conceptual diagram with which it demonstrates for the case where the interleaving process is performed in the transmission side in the conventional CIBS-CDMA system, and the deinterleaving process is performed in the receiving side. It is a table | surface used for description of the error rate characteristic by the conventional CIBS-CDMA system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,90 ... Wireless communication system 11, 91 ... Transmission side, 12, 92 ... Reception side, 35 ... IQ exchange processing part, 37, 44 ... IQ exchange instruction part, 45 ... IQ exchange decoding process , 71... Frequency domain equalization unit, 21... Mobile communication device, 22... Base station, 23.

Claims (9)

In a wireless communication system having a plurality of wireless communication devices that transmit / receive information signals by performing spread modulation processing,
Among the wireless communication devices, on the transmission side,
Repeated transmission means for repeatedly transmitting the same transmission data as transmission data obtained by performing spread modulation processing on the information signal at least twice;
A first switching unit provided in a preceding stage or a subsequent stage of the repetitive transmission means, wherein the in-phase and quadrature components orthogonal to each other in the transmission data are replaced at a preset period when retransmitted;
Among the wireless communication devices, on the receiving side,
Second transmission means for replacing the in-phase and quadrature components with the same period as the period set by the first replacement means for transmission data transmitted from the repeated transmission means;
And adding means for adding the received data in which the in-phase and quadrature components are exchanged by the second exchanging means and the received data in which the in-phase and quadrature components are not exchanged by the second exchanging means. A wireless communication system. On the receiving side,
The wireless communication system according to claim 1, further comprising: a transmission line compensation unit that is provided upstream of the second switching unit and compensates for phase fluctuations that occur between the transmission line or the transceiver. On the sending side,
Code division multiplexing processing means provided before the first switching means for code division multiplexing processing of transmission data obtained by performing spread modulation processing on the information signal, wherein the number of pieces of information included in the transmission data is at least halved The wireless communication system according to claim 1, wherein the wireless communication system is compensated so as to perform. In a wireless communication method for transmitting and receiving information signals by performing spread modulation processing between a plurality of wireless communication devices,
Among the wireless communication devices, on the transmission side,
After transmitting the same transmission data as the transmission data obtained by performing the spread modulation process on the information signal at least twice, a cycle set in advance when retransmitting the in-phase and quadrature components orthogonal to each other in the transmission data Replace with
Among the wireless communication devices, on the receiving side,
For transmission data transmitted from the transmission side, after replacing the in-phase and quadrature components in the same cycle as the set cycle, the received data in which the in-phase and quadrature components are replaced, and the in-phase and quadrature components are A wireless communication method characterized by adding received data that has not been replaced. On the receiving side,
The wireless communication method according to claim 4, wherein the transmission data transmitted from the transmission side is compensated for a phase variation that occurs between a transmission path or a transceiver. On the sender side,
6. The transmission data obtained by performing spread modulation processing on the information signal is subjected to code division multiplexing processing to compensate so that the number of information included in the transmission data is at least halved. The wireless communication method described. In a wireless communication apparatus that transmits and receives an information signal by performing spread modulation processing,
Repeated transmission means for repeatedly transmitting the same transmission data as transmission data obtained by performing spread modulation processing on the information signal at least twice;
A transmission system provided in a preceding stage or a subsequent stage of the repetitive transmission means, and having a first replacement means for replacing in-phase and quadrature components orthogonal to each other in the transmission data at a preset cycle when retransmitting;
Second transmission means for replacing the in-phase and quadrature components with the same period as the period set by the first replacement means for transmission data transmitted from the repeated transmission means;
A reception system comprising: reception data in which the in-phase and quadrature components are replaced by the second replacement means; and addition means for adding the reception data in which the in-phase and quadrature components are not replaced by the second replacement means. And a wireless communication device. In the receiving system,
The wireless communication apparatus according to claim 7, further comprising: a transmission path compensation unit that is provided before the second switching unit and compensates for phase fluctuations that occur between the transmission path or the transceiver. In the transmission system,
Code division multiplexing processing means provided before the first switching means for code division multiplexing processing of transmission data obtained by performing spread modulation processing on the information signal, wherein the number of pieces of information included in the transmission data is at least halved The wireless communication apparatus according to claim 7, wherein the wireless communication apparatus is compensated to do so.

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