Wireless communication apparatus

The present invention relates to a wireless communication device, and particularly wireless communication of a mobile phone or the like using a highly efficient power amplification method when a multi-carrier signal using a small number of carriers (carrier waves) of about 2 to 3 is used as a transmission modulation wave. Regarding the device.

Mobile phones have continued to make remarkable technological progress in recent years, but in the past, they were in stages of 1st generation (analog mobile phones), 2nd generation (digital mobile phones), and 3rd generation (IMT-2000). Has made progress. At present, standardization work and research and development of the next 4th generation (Beyond IMT-2000) have already begun with the goal of commercialization around 2010.

The configuration of the RF (radio frequency) circuit of a wireless communication device is affected by the modulation method of RF electrical signals defined by the standard of the wireless communication system. The 4th generation standardization work has not yet progressed, but as a modulation method for its uplink (communication from mobile phones to the base station (sometimes called "uplink" or "Reverse Link")). The MC / DS-CDMA (Multi Carrier / Direct Spread-Code Division Multiple Access) system recommended by NTT DoCoMo is promising.

Regarding this MC / DS-CDMA system, for example, Article No. B-5-72 "Overview of Broadband Radio Access Experimental Equipment" at the 2003 IEICE General Conference, and Article No. B-5-77 "Uplink Multi" It is disclosed in "Results of laboratory experiments on throughput characteristics in carrier / DS-CDMA broadband radio access". According to [Table 2] in Reference B-5-72 and [Table 1] in Reference B-5-77, DS-CDMA signals with a bandwidth of 20 MHz per carrier (direct sequence spread spectrum) (direct sequence spread spectrum) It can be seen that the converted signals) are arranged on the frequency axis for two carriers to form a modulated signal with a total occupied bandwidth of 40 MHz. Fig. 5 shows this in a schematic spectrum diagram. The modulated wave 501 by the first carrier and the modulated wave 502 by the second carrier are arranged adjacent to each other on the frequency axis. In the MC / DS-CDMA system, each of the two carriers is a modulated wave having a bandwidth of 20 MHz, and the two carriers together occupy a bandwidth of 40 MHz.

In this way, the MC / DS-CDMA system is a multi-carrier signal that uses a plurality of carriers, albeit only two. Moreover, since each carrier is a DS-CDMA signal, it can be seen that linear amplification is required.

Further, [FIG. 1 (2)] in Document B-5-72 shows a schematic block diagram of a wireless communication terminal using this MC / DS-CDMA system as a transmission modulation system. FIG. 7 in the present specification is an arrangement of the figures in this document by omitting parts unnecessary for the description of the present invention.

In FIG. 7, the transmission modulated wave generated by the modulation wave source circuit 701 is processed (amplification, frequency conversion, band limitation, etc.) by the RF transmission circuit 702, passes through the transmission amplifier circuit and the duplexer circuit 703, and is passed through the transmission amplifier circuit and the duplexer circuit 703 to the antenna element 704 or the antenna. It is sent from the element 705. On the contrary, the received modulated wave received by the antenna element 704 or the antenna element 705 passes through the receiving amplifier circuit and the duplexer circuit 703 and is processed by the RF receiving circuit 706 (amplification, frequency conversion, removal of unnecessary frequency components, etc.). It is demodulated by the demodulation circuit 707.

By the way, in a wireless communication terminal such as a mobile phone, the power consumption of a transmission amplifier circuit, that is, a power amplifier (power amplifier) used immediately before an antenna of a transmission system is an extremely serious problem. The power amplifier is a circuit that amplifies the modulated signal of the minute power of the mW order created by the signal processing unit to the large power of the W order at a stretch and sends it to the transmitting antenna. Since it handles a large amount of power on the order of W, a power amplifier is generally a component that consumes a large amount of power among all electronic components. Therefore, in order to reduce the power consumption of the wireless communication terminal, it is extremely important to reduce the power consumption and the efficiency of the power amplifier.

If the power amplifier is highly efficient, the continuous talk time of the mobile phone can be extended for the same capacity battery. Further, if the continuous talk time is increased as a result, the capacity of the battery can be reduced, and the weight, size, and cost of the entire mobile phone can be reduced. In this way, improving the efficiency of power amplifiers is a serious problem that is directly linked to the commercial value and convenience of mobile phones.

As the circuit configuration of the power amplifier for the multi-carrier signal as shown in FIG. 5, two methods, the "batch amplification method" shown in FIG. 8 and the "individual amplification method" shown in FIG. 9, are known. The difference between the batch amplification method and the individual amplification method is described in detail in, for example, the [conventional technique] portion of Japanese Patent Application Laid-Open No. 2000-68958 (Patent Document 1).

FIG. 8, which is a batch amplification method, is an arrangement of [FIG. 12] in Patent Document 1 by omitting parts not related to the gist of the present invention. The plurality of carriers (carrier waves) individually generated by the plurality of modulated wave source circuits 801 to 804 are first bundled into one signal line by the power synthesis circuit 805, amplified collectively by the power amplifier 806, and antenna element 807. Is sent from. The batch amplification method is a method generally used in home appliances because of its simple circuit configuration, small size, and low cost. For example, in a wireless LAN product of the IEEE802.11a standard for personal computers, an OFDM signal, which is a typical multicarrier signal, is amplified by a batch amplification method.

However, when the multi-carrier signal is amplified by the batch amplification method, it is widely known that the efficiency of the power amplifier is significantly deteriorated and the power consumption is increased. The cause is that the amplitude fluctuation of the signal becomes remarkable because a plurality of carriers are instantaneously synthesized and strengthened each other, or conversely cancel each other. This problem is described in many documents, including the [conventional technology] part of JP-A-9-149090.

Therefore, for the purpose of improving the efficiency of the power amplifier, an attempt has been made to use the individual amplification method shown in FIG. 9 instead of the batch amplification method shown in FIG. FIG. 9, which is an individual amplification method, is an arrangement of [FIG. 11] in Patent Document 1 by omitting parts not related to the gist of the present invention. The plurality of carriers (carrier waves) individually generated by the plurality of modulated wave source circuits 901 to 904 are individually amplified by the plurality of power amplifiers 905 to 908, and then converted into one multi-carrier signal by the power synthesis circuit 913. Bundled. Specifically, the power synthesis circuit 913 is realized by an isalator circuit 909 to 912 for preventing interference between the power amplifiers 905 and 908 due to signal reflection, a resistance matching circuit, and the like. The multicarrier signal whose power is synthesized in this way is transmitted by the antenna element 914.

It is considered that the individual amplification method as shown in FIG. 9 has a possibility of improving the efficiency of the power amplifier as compared with the batch amplification method as shown in FIG. The reason is that in the individual amplification method (Fig. 9), even if the final output is a multi-carrier signal, it is only a single-carrier signal when it passes through the individual amplifiers 905 to 908, so the amplitude fluctuation can be suppressed to a small value. Because.

However, there are some technical problems in actually realizing the individual amplification method (Fig. 9) at the level of home appliances, and the major problem is the power synthesis circuit. For example, in the case of the power synthesis circuit 913 shown in FIG. 9, the increase in size and cost due to the use of a large number of isarator components and the power loss due to resistance are unavoidable. In particular, the loss due to resistance means that even if the power amplifiers 905 to 908 can amplify with high efficiency, a part of the amplified power will be wasted, and in the end, the power consumption will increase. You could end up with it.

The reason why it is necessary to use a circuit that causes loss due to resistance as the power synthesis circuit 913 is that the multi-carrier signal (Fig. 5) assumed by the present invention has two carriers 501 and 502 on the frequency axis without any guard band. This is because it is a signal in a bad condition that they are adjacent to each other. If there is a guard band between the two carriers 501 and 502 and the frequency bands are separated from each other, there is a known means to secure iseration between terminals to prevent mutual interference and to realize power synthesis without loss. Has been done. For example, a duplexer circuit is a typical example of a lossless power synthesis circuit under such favorable conditions. However, there is no known method for realizing a lossless power synthesis circuit that can be easily realized on a circuit board under adverse conditions equivalent to no guard band as shown in FIG.

As a countermeasure to this problem in the prior art, for example, Patent Document 1 claims that the isarator circuits 909 to 912 of the power synthesis circuit 913 in FIG. 9 can be omitted by using a variable filter circuit or the like. .. However, even in Patent Document 1, it has not been possible to present a means for making the matching circuit lossless by using a resistor located next to the isarator circuit.

As described above, the individual amplification method (FIG. 9) is actually difficult to realize because the power synthesis circuit 913 is subject to strict requirements.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2000-68958</text></patcit>

<p> An object of the present invention is to realize a wireless communication terminal capable of small size, light weight, and long-time communication in a wireless communication system using a multi-carrier signal, for example, a "fourth generation" mobile phone.</p><p> Therefore, the problem to be solved by the present invention is to provide a compact and low-cost wireless communication device capable of high-efficiency power amplification of a multicarrier signal for each carrier by an individual amplification method and then power synthesis with low loss. is there.</p>

<p> In order to achieve the above object, the wireless communication device of the second invention includes M antenna elements (M is a natural number of 2 or more), M modulated wave source circuits, M power amplifier circuits, and M pieces. It is a wireless communication device that has the amplifier circuit of the above, adopts the frequency division duplex (FDD) method, and uses a multi-carrier signal using M carriers with different center frequencies as a transmission modulation wave. , The transmission modulated wave by the Nth carrier output by the Nth (N = 1, ..., M) modulation wave source circuit is amplified by the Nth power amplifier circuit, and is amplified by the Nth power amplifier circuit. By transmitting from the Nth antenna element through the duplexer circuit of the above, transmission modulation waves by a total of M carriers from the first to the Mth are transmitted from the M antenna elements, respectively. After that, space power is combined, and diversity reception is performed by the M antenna elements. Here, the frequency division duplex method (FDD method) is a communication method in which two waves of different frequencies are used for transmission and reception at the same time.</p><p> According to the wireless communication device having the above configuration, the M antenna elements capable of diversity reception are generally arranged so that the mutual electromagnetic coupling is small, so that the M antenna elements transmitted from the M antenna elements are arranged. The carrier transmission modulated waves do not electromagnetically couple with each other and enter other antennas, and are smoothly transmitted into space. As a result, power synthesis can be performed without causing any loss. Moreover, it can be realized without significantly increasing the number of parts and cost. Therefore, the efficiency of the power amplifier can be significantly improved, and a wireless communication terminal with low power consumption can be realized. In addition, the increase in the number of parts and the cost can be minimized.</p><p> The wireless communication device of the second invention includes M antenna elements (M is a natural number of 2 or more), M modulation wave source circuits, M power amplifier circuits, and M transmission / reception changeover switch circuits. It is a wireless communication device that adopts the Time Division Duplex (TDD) method and uses a multi-carrier signal using M carriers with different center frequencies as a transmission modulation wave. The transmission modulation wave by the Nth carrier output by the modulation wave source circuit of the th (N = 1, ..., M) is amplified by the power amplifier circuit of the Nth, and the transmission and reception of the Nth. By transmitting from the Nth antenna element through the changeover switch circuit, transmission modulation waves by a total of M carriers from the first to the Mth are transmitted from each of the M antenna elements. It is characterized in that space power is later combined and diversity reception is performed by the M antenna elements. Here, the time division duplex system (TDD system) is a communication system in which the same frequency is used for transmission and reception by dividing the time.</p><p> According to the wireless communication device having the above configuration, the M antenna elements capable of diversity reception are generally arranged so that the mutual electromagnetic coupling is small, so that the M antenna elements transmitted from the M antenna elements are arranged. The carrier transmission modulated waves do not electromagnetically couple with each other and enter other antennas, and are smoothly transmitted into space. As a result, power synthesis can be performed without causing any loss. Moreover, it can be realized without significantly increasing the number of parts and cost. Therefore, the efficiency of the power amplifier can be significantly improved, and a wireless communication terminal with low power consumption can be realized. In addition, the increase in the number of parts and the cost can be minimized.</p><p> Further, in the wireless communication device of the first and second inventions, the polarization planes of the M antenna elements are arranged so as to face directions substantially 90 degrees apart from each other.</p><p> By arranging the polarization planes of the M antenna elements so as to face directions substantially 90 degrees apart from each other, the electromagnetic coupling between the antenna elements becomes smaller and power synthesis without loss is effectively performed.</p>

<p> As is clear from the above, according to the wireless communication device of the present invention, it is possible to provide a small-sized and low-cost circuit means capable of power-amplifying a multicarrier signal with high efficiency. As a result, for example, in a 4th generation mobile phone system or the like, which is expected to adopt MC / DS-CDMA modulated waves, it is possible to realize miniaturization and weight reduction of terminals and to realize long-term calls.</p>

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

(First Embodiment) FIG. 1 is a schematic block diagram of the wireless communication device of the first embodiment according to the present invention. This first embodiment assumes a case where the transmitted modulated wave consists of two carriers as shown in FIG. 5, and also assumes a communication system adopting the FDD (Frequency Division Duplex) method. .. As mentioned above, this corresponds to the 4th generation mobile phones that are expected to adopt the MC / DS-CDMA system.

In FIG. 1, the first carrier 501 of the modulated waves shown in FIG. 5 is generated by the first modulated wave source circuit 101, amplified by the first power amplifier 103, and passed through the first duplexer circuit 105. It is sent from the antenna element 107 of 1. On the other hand, the second carrier 502 of the modulated waves shown in FIG. 5 is generated by the second modulated wave source circuit 102, amplified by the second power amplifier 104, and passed through the second duplexer circuit 106 to the second carrier 502. It is sent from the antenna element 108. As a result, the two carrier components 501,502 are spatially power-synthesized almost losslessly after being transmitted from the two antenna elements 107,108.

In order to assist the explanation of the circuit operation of the wireless communication device, a schematic spectrum diagram (113 to 115) which is a simplification of FIG. 5 is drawn in FIG. The output spectrum 113 of the power amplifier 103 is a single carrier signal composed of only the first carrier component 501 in FIG. The output spectrum 114 of the power amplifier 104 is a single carrier signal consisting of only the second carrier component 502 in FIG. The spectrum 115 after the spatial power synthesis of these signals through the two antenna elements 107 and 108 becomes the same multicarrier signal as in FIG.

One of the gist of the present invention is that the two antenna elements 107 and 108 for individually transmitting the two carriers 501 and 502 in the transmitting system are also utilized for diversity reception in the receiving system. Antenna elements intended for diversity reception are generally arranged so that mutual electromagnetic coupling is small. For example, the planes of polarization are arranged so as to be offset by approximately 90 degrees to enhance the polarization diversity effect. Therefore, the two carrier components 501 and 502 transmitted from the two antenna elements 107 and 108 are smoothly transmitted into the space without electromagnetically coupling to each other and entering the other antenna. As a result, the function corresponding to the power synthesis circuit 913 in FIG. 9 is realized without causing any loss due to resistance components or the like, and without significantly increasing the number of parts and the cost.

The operation of the receiving system in FIG. 1 will be described below. The purpose of the receiving system in the first embodiment is that diversity reception using two antenna elements 107 and 108 is adopted, and the circuit is more than that. It does not go into the details of the realization method of. It should be emphasized that the details of the receiving system in Fig. 1 are just an example in line with this purpose.

The first received signal that has passed through the first duplexer circuit 105 from the first antenna element 107 and the second received signal that has passed through the second duplexer circuit 106 from the second antenna element 108 are among them. The one with the better reception state is selected by the diversity switch circuit 109, amplified by the LNA circuit 111 after the unnecessary frequency component is removed by the filter circuit 110, and demodulated by the demodulation circuit 112.

As described above, according to the wireless communication device of the second embodiment, the efficiency of the power amplifier can be significantly improved and the wireless communication terminal with low power consumption can be realized by the individual amplification method and the lossless power synthesis. .. At that time, the increase in the number of parts and the cost is minimized, and in particular, the antenna element, which is a component whose size is remarkably large among all the parts, is completely increased as compared with the conventional technology (Fig. 7) that performs diversity reception. There is no need.

(Second Embodiment) FIG. 2 is a schematic block diagram of the wireless communication device of the second embodiment according to the present invention. The wireless communication device shown in FIG. 1 of the first embodiment was an embodiment for the modulated wave of FIG. 5 using two carriers, but the wireless communication device shown in FIG. 2 of the second embodiment is 3 This is an extension of the case for the modulated wave of FIG. 6 using the carrier of the book. In FIG. 6, the three modulated waves 601,602,603 by the first to third carriers are arranged adjacent to each other on the frequency axis.

The first carrier 601 of the modulated waves shown in FIG. 6 is generated by the first modulated wave source circuit 201, amplified by the first power amplifier 204, and passed through the first duplexer circuit 207 to the first antenna element. Sent from 210. The second carrier 602 of the modulated waves shown in FIG. 6 is generated by the second modulated wave source circuit 202, amplified by the second power amplifier 205, and passed through the second duplexer circuit 208 to the second antenna element. It is sent from 211. Further, the third carrier 603 of the modulated waves shown in FIG. 6 is generated by the third modulated wave source circuit 203, amplified by the third power amplifier 206, and passed through the third duplexer circuit 209. It is sent from the antenna element 212. As a result, the three carrier components 601,602,603 are spatially power-synthesized almost losslessly after being transmitted from the three antenna elements 210,211,212.

In order to assist the explanation of the circuit operation of the wireless communication device, a schematic spectrum diagram (217 to 220) which is a simplification of FIG. 6 is drawn in FIG. The output spectrum 217 of the power amplifier 204 is a single carrier signal consisting of only the first carrier component 601 in FIG. The output spectrum 218 of the power amplifier 205 is a single carrier signal consisting of only the second carrier component 602 in FIG. The output spectrum 219 of the power amplifier 206 is a single carrier signal consisting of only the third carrier component 603 in FIG. The spectrum 220 after the spatial power synthesis of these signals through the three antenna elements 210 to 212 becomes the same multicarrier signal as in FIG.

In the receiving system, the first received signal passing through the first duplexer circuit 207 from the first antenna element 210 and the second receiving signal passing through the second duplexer circuit 208 from the second antenna element 211. Of the signal and the third received signal that has passed from the third antenna element 212 to the third duplexer circuit 209, one of which has a good reception state is selected by the diversity switch circuit 213 and is selected by the filter circuit 214. After removing unnecessary frequency components, it is amplified by the LNA circuit 215 and demodulated by the duplexer circuit 216.

Since the three antenna elements 210, 211, 212 are intended for diversity reception, they are arranged so that the electromagnetic coupling between them is small. As an example, FIG. 4 shows an example in which three rod-type antennas are provided with a polarization diversity effect in a mobile phone. In FIG. 4, one of the rod-type antennas 402 outside the housing 401 of the mobile phone and the two rod-type antennas 403 and 404 hidden inside the housing 401 are displaced by approximately 90 degrees from each other 3 It is arranged three-dimensionally. Therefore, the three antennas 402, 403, 404 have polarization planes that are 90 degrees apart from each other, and the electromagnetic coupling between them becomes small.

As described above, according to the wireless communication device of the second embodiment, the efficiency of the power amplifier can be significantly improved and the wireless communication terminal with low power consumption can be realized by the individual amplification method and the lossless power synthesis. .. In addition, the increase in the number of parts and the cost is minimized, and in particular, the antenna element, which is a component whose size is remarkably large among all the parts, does not need to be increased at all as compared with the conventional case of performing diversity reception.

(Third Embodiment) FIG. 3 is a schematic block diagram of the wireless communication device of the third embodiment according to the present invention. The wireless communication device of FIG. 1 of the first embodiment was in the case of a communication system adopting an FDD (Frequency Division Duplex) system, but the wireless communication device shown in FIG. 3 of this third embodiment is TDD ( It is a communication system that adopts the Time Division Duplex) method. As the modulated wave, the spectrum shown in the schematic diagram of FIG. 5 is assumed as in the case of FIG.

The first carrier 501 of the modulated waves shown in FIG. 5 is generated by the first modulated wave source circuit 301, amplified by the first power amplifier 303, and passed through the first transmission / reception changeover switch circuit 305. It is sent from the antenna element 307. The second carrier 502 of the modulated waves shown in FIG. 5 is generated by the second modulated wave source circuit 302, amplified by the second power amplifier 304, and passed through the second transmission / reception changeover switch circuit 306. It is sent from the antenna element 308. As a result, the two carrier components 501,502 are spatially power-synthesized almost losslessly after being transmitted from the two antenna elements 307,308.

In order to assist the explanation of the circuit operation of the wireless communication device, a schematic spectrum diagram (313 to 315) which is a simplification of FIG. 5 is drawn in FIG. The output spectrum 313 of the power amplifier 303 is a single carrier signal composed of only the first carrier component 501 in FIG. The output spectrum 314 of the power amplifier 304 is a single carrier signal consisting of only the second carrier component 502 in FIG. The spectrum 315 after the spatial power synthesis of these signals through the two antenna elements 307 and 308 becomes the same multicarrier signal as in FIG.

In the receiving system, the first received signal that has passed from the first antenna element 307 to the first transmission / reception changeover switch circuit 305 and the second transmission / reception changeover switch circuit 306 from the second antenna element 308 have passed. The second received signal, which has a better reception condition, is selected by the diversity switch circuit 309, is amplified by the LNA circuit 311 after the unnecessary frequency component is removed by the filter circuit 310, and is amplified by the demodulation circuit 312. It is demodulated.

In this way, even in the case of the TDD method, as in the case of the FDD method, it is possible to realize high efficiency of the power amplifier while keeping the number of parts and cost to a minimum. That is, a wireless communication terminal with low power consumption can be realized.

In the first to third embodiments, a wireless communication device using a multi-carrier signal using two or three carriers having different center frequencies as a transmission modulation wave has been described, but four or more carriers having different center frequencies have been described. The present invention may be applied to a wireless communication device using a multi-carrier signal using the above as a transmission modulation wave.

<figref num="1">FIG. 1 is a block diagram of the wireless communication device of the first embodiment according to the present invention.</figref><figref num="2">FIG. 2 is a block diagram of the wireless communication device according to the second embodiment of the present invention.</figref><figref num="3">FIG. 3 is a block diagram of the wireless communication device according to the third embodiment of the present invention.</figref><figref num="4">FIG. 4 is a schematic diagram of the arrangement of the antenna elements of the wireless communication device according to the present invention.</figref><figref num="5">FIG. 5 is a schematic diagram of a multicarrier signal targeted by the present invention.</figref><figref num="6">FIG. 6 is a schematic diagram of a multicarrier signal targeted by the present invention.</figref><figref num="7">FIG. 7 is a block diagram of a wireless communication device according to the prior art.</figref><figref num="8">FIG. 8 is a block diagram of a transmission system of a wireless communication device according to a conventional technique (batch amplification method).</figref><figref num="9">FIG. 9 is a block diagram of a transmission system of a wireless communication device according to a conventional technique (individual amplification method).</figref>

Code description

101,102,201,202,203,301,302,701,801,802,803,804,901,902,903,904 ... Modulated wave source circuit 103,104,204,205,206,303,304,806,905,906,907,908 ... Power amplifier circuit 105,106,207,208,209 ... Duplexer circuit 107,108,210,211,212,307,308,704 113,114,115,217,218,219,220,313,314,315 ... Spectrum 305,306 ... Transmission / reception switch circuit 401 ... Mobile phone housing 402,403,404 ... Rod type antenna 501,601 ... Modulated wave by 1st carrier 502,602 ... Modulated wave by 2nd carrier 603 ... Modulated wave by 3rd carrier 702 ... RF transmitter circuit 703 ... Transmit amplifier circuit, receiver amplifier circuit and duplexer circuit 706 ... RF receiver circuit 805,913 ... Power synthesis circuit 913,914,915,916 ... Isarator circuit