JP4876062B2 - Wireless receiver - Google Patents

Description

  The present invention relates to a radio receiving apparatus that divides a wide band radio transmission path into a plurality of frequency bands and performs frequency hopping in each band to receive a high frequency signal.

  Conventionally, as this type of wireless receiving apparatus, a device that stores propagation loss for each reception frequency in advance and performs level control according to the reception frequency to keep the broadband frequency characteristics of the wireless transmission line flat is known. (For example, refer to Patent Document 1).

  On the other hand, in the field of wireless communication technology used in offices and homes, for example, wireless LAN (Local Area Network) communication based on IEEE802.11 standards and Wireless-USB (Wireless-Universal Serial Bus) standards Wireless PAN (Personal Area Network) communication has been put into practical use, and various products have been put on the market.

  Some of these wireless standards define a frequency hopping function in order to perform frequency spreading. For example, in the Wireless-USB standard, three bands called “band” every 528 MHz are collectively referred to as a “band group”, and frequency hopping is performed for each symbol within the band group.

  Therefore, it is necessary to flatten the frequency characteristics of the wireless transmission path over a wide band of 1584 MHz, which is a combination of the three band bands. However, since it is affected by the frequency characteristics of the transmission level output, the frequency characteristics of the spatial propagation loss, the frequency characteristics of the receiving amplifier, and the frequency characteristics of the PCB (Printed Circuit Board) loss, it is possible to keep the frequency characteristics flat over a wide band. It was difficult.

  For this reason, conventionally, it has been considered to keep the frequency characteristics of the wireless transmission path flat over a wide band by correcting the frequency characteristics of the transmission characteristics and the reception characteristics. For example, as a method of correcting the frequency characteristic on the transmission side, there is one that performs transmission power control for correcting the spatial propagation loss characteristic according to the hopping frequency, and keeps the frequency characteristic of the wireless transmission path flat over a wide band (for example, , See Patent Document 2).

  In order to correct the frequency characteristics on the receiving side, propagation loss for each reception frequency is stored in advance, and level control according to the reception frequency is performed to keep the frequency characteristics of the wireless transmission line flat over a wide band. (For example, refer to Patent Document 1).

Also, as a means to correct the frequency characteristics on the receiving side, AGC (Automatic Gain Control) corresponding to minute level fluctuations that occur in a relatively short time by finely controlling the gain of an IF (Intermediate Frequency) amplifier. In addition, there is a combination of AGC and AGC corresponding to a large level fluctuation that changes in a relatively long time by controlling a high-frequency variable gain amplifier (see, for example, Patent Document 3).
JP 2006-229739 A JP 2005-269202 A JP 2006-290178 A

  However, what is disclosed in Patent Document 1 can only keep the frequency characteristic of the receiving side flat, and the frequency characteristic of the intermediate frequency signal is affected by the frequency characteristic and the spatial transmission loss characteristic of the transmitting side. There has been a problem that the level of the intermediate frequency signal cannot be kept constant.

  In addition, what is disclosed in Patent Document 2 can only keep the frequency characteristic of the transmission side flat, and the frequency characteristic of the intermediate frequency signal is affected by the spatial transmission loss characteristic and the frequency characteristic of the reception side. There has been a problem that the level of the intermediate frequency signal cannot be kept constant.

  Further, the technique disclosed in Patent Document 3 can perform AGC corresponding to minute level fluctuations that occur in a relatively short time by finely controlling the gain of the IF amplifier, and controls the reception level to be constant. be able to.

  However, when performing high-speed frequency hopping in which the frequency is hopped for each symbol, such as Wireless-USB, it is necessary to shorten the time until the reception level is stabilized.

  In the case of Wireless-USB, the period during which a valid signal exists within one symbol is 242 ns, and even if the time during which the reception level is stabilized is 10 ns, reception performance is affected. For this reason, the one disclosed in Patent Document 3 does not affect the reception performance of Wireless-USB, considering the influence of the delay of the frequency conversion means for converting to an intermediate frequency signal and the delay of the intermediate frequency variable gain amplifier. It is impossible to detect the input level for each symbol and perform feedback AGC in real time.

  As described above, the technique disclosed in Patent Document 3 has a problem that the level of the intermediate frequency signal cannot be kept constant on the receiving side when performing high-speed frequency hopping communication in which the center frequency is changed for each symbol. It was.

  The present invention has been made to solve such a conventional problem. When performing high-speed frequency hopping communication in which the center frequency is changed for each symbol, the frequency characteristics of the entire path from the transmission device to the wireless reception device are provided. An object of the present invention is to provide a radio receiving apparatus that can keep the level of the intermediate frequency signal constant on the receiving side without being influenced by the above.

The wireless receiver according to the present invention includes a hopping control unit that changes a center frequency for each symbol based on a frequency hopping pattern defined by the Wireless-USB standard, and a received high-frequency signal based on the center frequency. A frequency converting means for converting to a frequency signal, a level detecting means for detecting the level of each intermediate frequency signal converted by the frequency converting means during the cycle of the frequency hopping pattern, and a level detecting means for detecting the level. The level storage means for storing the level of the intermediate frequency signal for each center frequency, the intermediate frequency variable gain amplifier for amplifying the intermediate frequency signal, and the frequency hopping pattern are stored in the level storage means after one cycle. Depending on the level of each center frequency, the intermediate frequency can be And a gain adjusting means for adjusting the gain of the variable gain amplifier.

  With this configuration, the radio reception apparatus of the present invention adjusts the gain of the intermediate frequency variable gain amplifier according to the level of the intermediate frequency signal stored for each center frequency, so that the center frequency is changed for each symbol. When performing frequency hopping communication, the level of the intermediate frequency signal can be kept constant on the receiving side without being affected by the frequency characteristics of the entire path from the transmitting device to the wireless receiving device.

  The level detection means detects the level of a preamble symbol at the head of the frame, and the gain adjustment means determines the preamble symbol according to the level of the preamble symbol of each center frequency stored in the level storage means. The gain of the intermediate frequency variable gain amplifier for subsequent data symbols may be adjusted.

  With this configuration, the radio reception apparatus of the present invention corrects the level difference due to the center frequency using each level of the intermediate frequency signal of the preamble symbol at the head of the frame, and therefore, high-speed frequency hopping communication that changes the center frequency for each symbol. When performing the above, it is possible to keep the level of the intermediate frequency signal constant on the receiving side without being affected by the frequency characteristics of the entire path from the transmitting device to the wireless receiving device.

  The gain adjusting means may adjust the gain of the intermediate frequency variable gain amplifier for the data symbol in accordance with the average value of the preamble symbol level of each center frequency stored in the level storing means. Good.

  With this configuration, the radio reception apparatus of the present invention corrects the level difference due to the center frequency using each average value of the intermediate frequency signal level of the preamble symbol at the head of the frame, so that the high-speed that changes the center frequency for each symbol. When performing frequency hopping communication, the level of the intermediate frequency signal can be kept constant on the receiving side without being affected by the frequency characteristics of the entire path from the transmitting device to the wireless receiving device.

  The level detection means may detect the level of the intermediate frequency signal at a different timing for each of the center frequencies at which the output of the intermediate frequency variable gain amplifier is stabilized.

  With this configuration, the radio reception apparatus of the present invention appropriately adjusts the gain of the intermediate frequency variable gain amplifier so that the level detection means can detect the level of the intermediate frequency at a stable timing when the transient characteristic period of the level detection means has elapsed. can do.

  In the present invention, when performing high-speed frequency hopping communication in which the center frequency is changed for each symbol, the level of the intermediate frequency signal is set on the receiving side without being affected by the frequency characteristics of the entire path from the transmitting device to the wireless receiving device. A wireless receiver that can be kept constant can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, an example in which the wireless reception device according to the present invention is applied as a wireless-USB wireless reception device will be described.

(First embodiment)
FIG. 1 is a block diagram showing a radio reception apparatus according to the first embodiment of this invention.

  In FIG. 1, a radio receiving apparatus 1 includes an antenna 10 that receives a high-frequency signal, a low-noise amplifier 11 that amplifies the received high-frequency signal, a local transmitter 12 that generates a local frequency signal, and a local high-frequency signal. A frequency converter 13 for converting to an intermediate frequency signal by mixing the frequency signal and an intermediate frequency variable gain amplifier 14 for amplifying the intermediate frequency signal are provided.

  The wireless receiver 1 also includes a level detector 15 that detects the level of the intermediate frequency converted by the frequency converter 13, a hopping controller 16 that hops the frequency to perform frequency hopping communication, and a level detector 15. Level storage units 17a to 17c that store the level detected by each of the center frequencies, and a gain setting value calculation unit 18 that calculates a gain setting value for each center frequency based on the levels stored in the level storage units 17a to 17c. A gain setting value storage unit 19a to 19c that stores the gain setting value calculated by the gain setting value calculation unit 18, and one gain selected from the gain setting values stored in the gain setting value storage units 19a to 19c. Gain setting value selection unit for setting the setting value as the gain of the intermediate frequency variable gain amplifier 14 It is further provided with a 0 and.

  In FIG. 1, three level storage units 17a to 17c and gain setting value storage units 19a to 19c are shown. However, in Wireless-USB, when the number of channels is 9, the frequency is 3 symbols. This is because the hopping pattern makes a round, so that three level storage units and three gain setting value storage units are required, and the number of level storage units and gain setting value storage units constituting the radio reception apparatus of the present invention is limited. It is not a thing. Further, the level storage units 17a to 17c constitute level storage means in the present invention.

  The level detector 15 detects the level of the intermediate frequency signal converted by the frequency converter 13, and stores the detected level in the level storage units 17a to 17c for each center frequency. The level detector 15 constitutes level detecting means in the present invention.

  The hopping control unit 16 changes the frequency of the local frequency signal generated by the local transmitter 12 according to the symbol, and indicates which center frequency the intermediate frequency signal converted by the frequency converter 13 corresponds to. A hopping control signal is generated.

  The gain setting value calculation unit 18 calculates a gain setting value for each center frequency based on the levels stored in the level storage units 17a to 17c, and stores the calculated gain setting values in the gain setting value storage units 19a to 19c, respectively. It comes to memorize.

  Based on the hopping control signal, the gain setting value selection unit 20 selects one gain setting value from the gain setting values stored in the gain setting value storage units 19a to 19c, and uses the selected gain setting value to change the intermediate frequency variable gain. The gain of the amplifier 14 is set. The gain setting value calculation unit 18, the gain setting value storage units 19a to 19c, and the gain setting value selection unit 20 constitute a gain adjusting unit in the present invention.

  The operation of the wireless reception device 1 configured as described above will be described with reference to FIG. FIG. 2 is a conceptual diagram for explaining the operation of each unit of the wireless reception device 1.

  In Wireless-USB, a channel for frequency hopping is defined for each symbol. The hopping pattern is determined by the standard. For example, in the case of 9 channels, three center frequencies of 3.432 GHz, 3.960 GHz, and 4.488 GHz are sequentially selected. In FIG. 2, the frequency 1 represents 3.432 GHz, the frequency 2 represents 3.960 GHz, and the frequency 3 represents 4.488 GHz.

  The Wireless-USB symbol is composed of a signal period of 242 ns and a no-signal period of 70 ns. In FIG. 2, the right direction corresponds to the progress of time, and the received signal is frequency hopped such as frequency 1, frequency 2, frequency 3, frequency 1, frequency 2, and frequency 3.

  Here, in general, the intermediate frequency signal frequency-converted by the wireless reception device is the frequency characteristic of the transmission device, the spatial transmission loss characteristic, and the frequency characteristic of the wireless reception device, that is, the entire path from the transmission device to the wireless reception device. Affected by the frequency characteristics.

  For example, the higher the frequency, the greater the spatial transmission loss, the greater the loss due to PCB mounting, and the lower the gain of a high-frequency low-noise amplifier. The higher the level, the lower the level.

  Therefore, in FIG. 2, the level of the intermediate frequency signal converted by the frequency converter 13 is a symbol as shown by A to C in FIG. 2 due to the influence of the frequency characteristics of the entire path from the transmitter to the radio receiver. The level of the symbol with the highest frequency 3 is the smallest.

  In the wireless reception device 1, first, the level storage unit 17 a stores the level of the intermediate frequency signal A with respect to the frequency 1 that is the first center frequency by the hopping control signal output by the hopping control unit 16. Similarly, the level of the intermediate frequency signal B for the next center frequency, frequency 2, is stored in the level storage unit 17b, and the level of the intermediate frequency signal C for the next center frequency, frequency 3, is stored in the level storage unit 17c. Is done.

  As described above, when the frequency hopping pattern is completed and the level of each intermediate frequency signal is stored in the level storage units 17a to 17c, the gain for each center frequency from the stored level to the intermediate frequency variable gain amplifier 14 is obtained. The set value is calculated by the gain set value calculation unit 18.

  Here, each gain setting value is calculated by the gain setting value calculation unit 18 so that the level of the intermediate frequency signal with respect to each center frequency is uniform. Specifically, the smaller the level stored in each of the level storage units 17a to 17c, the larger the gain of the intermediate frequency variable gain amplifier 14 needs to be. Therefore, the level stored in each of the level storage units 17a to 17c Each gain setting value is calculated so as to be proportional to the reciprocal.

  As described above, when the frequency hopping pattern is completed, each gain setting value stored in each gain setting value storage unit 19a to 19c is changed to the intermediate frequency variable gain by the gain setting value selection unit 20 in the next frequency hopping pattern. The gain of the amplifier 14 is sequentially set.

  For example, in the period D in the figure, the gain setting value for frequency 1 stored in the gain setting value storage unit 19 a is set as the gain of the intermediate frequency variable gain amplifier 14. Similarly, in the next symbol period, the gain setting value for frequency 2 stored in the gain setting value storage unit 19b is set as the gain of the intermediate frequency variable gain amplifier 14, and in the next symbol period, the gain setting value for frequency 3 is set. Is set as the gain of the intermediate frequency variable gain amplifier 14.

  As described above, the radio reception apparatus 1 of the present embodiment adjusts the gain of the intermediate frequency variable gain amplifier 14 according to the level of the stored intermediate frequency signal with respect to the center frequency for each symbol. When performing high-speed frequency hopping communication in which the center frequency is changed for each symbol, the level of the intermediate frequency signal is kept constant on the reception side without being affected by the frequency characteristics of the entire path from the transmission device to the wireless reception device 1. be able to.

(Second Embodiment)
FIG. 3 is a block diagram illustrating a radio reception apparatus according to the second embodiment of this invention. Note that in the present embodiment, the same components as those of the wireless reception device 1 of the first embodiment of the present invention are denoted by the same reference numerals, and description thereof is omitted.

  In Wireless-USB, data is transferred in units of frames, and the frequency hopping pattern is not changed within a frame. Therefore, when the frequency hopping pattern makes a round at the symbol at the head of the frame, the level of the intermediate frequency signal for each center frequency can be detected, and the gain setting value for each intermediate frequency can be calculated.

  Thereafter, in the frame, the gain of the intermediate frequency variable gain amplifier 14 can be set without updating the level of the intermediate frequency signal for each center frequency and the gain setting value for each intermediate frequency.

  FIG. 4 is a frame configuration diagram showing a Wireless-USB frame structure. The head of the frame is a PLCP (Physical layer convergence protocol) preamble symbol.

  The preamble symbol determines the level of the intermediate frequency signal for each center frequency and the gain setting value for each intermediate frequency, and receives data symbols such as a PLCP header and PSDU (PLCP Service Data Unit) following the preamble symbol. In the meantime, the gain of the intermediate frequency variable gain amplifier 14 can be set without updating the level of the intermediate frequency signal for each center frequency and the gain setting value for each intermediate frequency.

  In FIG. 3, the wireless reception device 21 is provided with a preamble detection unit 22 that detects a preamble symbol with respect to the wireless reception device 1 according to the first embodiment of the present invention. The preamble detector 22 and the level detector 15 constitute a level detector in the present invention.

  In general, since a preamble symbol has a known waveform, the preamble detector 22 detects the preamble symbol using autocorrelation.

  In the radio receiving apparatus 21 configured as described above, when a preamble symbol is detected by the preamble detection unit 22, an intermediate frequency with respect to the frequency 1 that is the first center frequency is detected by a hopping control signal output by the hopping control unit 16. The level of the signal A is stored in the level storage unit 17a. Similarly, the level of the intermediate frequency signal B for the next center frequency, frequency 2, is stored in the level storage unit 17b, and the level of the intermediate frequency signal C for the next center frequency, frequency 3, is stored in the level storage unit 17c. Is done.

  Here, in the level storage units 17a to 17c, the stored level is prohibited from being updated until the preamble detector 22 detects the next preamble symbol.

  As described above, when the frequency hopping pattern is completed and the level of each intermediate frequency signal is stored in the level storage units 17a to 17c, the gain for each center frequency from the stored level to the intermediate frequency variable gain amplifier 14 is obtained. The set value is calculated by the gain set value calculation unit 18.

  As described above, when the frequency hopping pattern is completed, each gain setting value stored in each gain setting value storage unit 19a to 19c is changed to the intermediate frequency variable gain by the gain setting value selection unit 20 in the next frequency hopping pattern. The gain of the amplifier 14 is sequentially set.

  As described above, the radio reception apparatus 21 according to the present embodiment corrects the level difference due to the center frequency using each level of the intermediate frequency signal of the preamble symbol at the head of the frame. When changing high-speed frequency hopping communication, the level of the intermediate frequency signal can be kept constant on the receiving side without being affected by the frequency characteristics of the entire path from the transmitting device to the wireless receiving device 21.

(Third embodiment)
FIG. 5 is a block diagram showing a radio reception apparatus according to the third embodiment of this invention. Note that in the present embodiment, the same components as those of the wireless reception device 21 of the second embodiment of the present invention are denoted by the same reference numerals, and description thereof is omitted.

  The wireless reception device 31 is provided with a gain setting value calculation unit 38 instead of the gain setting value calculation unit 18 with respect to the wireless reception device 21 according to the second embodiment of the present invention. The gain setting value calculation unit 38, together with the gain setting value storage units 19a to 19c and the gain setting value selection unit 20, constitutes a gain adjustment unit in the present invention.

  The gain setting value calculation unit 38 averages the levels stored in the level storage units 17a to 17c, calculates a gain setting value for each center frequency based on each averaged level, and calculates the calculated gain setting value. The gain setting values are stored in the gain setting value storage units 19a to 19c, respectively.

  A Wireless-USB frame includes at least 12 symbols of preamble symbols. For example, in the case of a 9-channel frame, since the frequency hopping pattern makes a round with 3 symbols, the frequency hopping takes 4 rounds during the preamble symbol period.

  Therefore, by averaging the four levels stored in each of the level storage units 17a to 17c with respect to each center frequency, a stable intermediate frequency signal level that is hardly affected by noise or the like can be obtained.

  As described above, the radio reception apparatus 31 according to the present embodiment corrects the level difference due to the center frequency using each average value of the intermediate frequency signal levels of the preamble symbol at the head of the frame. When performing high-speed frequency hopping communication that changes the center frequency, the level of the intermediate frequency signal can be kept constant on the receiving side without being affected by the frequency characteristics of the entire path from the transmitting device to the wireless receiving device 31. .

(Fourth embodiment)
FIG. 6 is a block diagram illustrating a wireless reception apparatus according to the fourth embodiment of this invention. Note that in the present embodiment, the same components as those of the wireless reception device 1 of the first embodiment of the present invention are denoted by the same reference numerals, and description thereof is omitted.

  The wireless receiver 41 is provided with a stable timing output unit 42 that instructs the level detector 15 to detect the level of the intermediate frequency with respect to the wireless receiver 1 according to the first embodiment of the present invention. . The stable timing output unit 42, together with the level detection unit 15, constitutes a level detection unit in the present invention.

  FIG. 7 shows the level of the intermediate frequency signal converted by the frequency converter 13 and the level detected by the level detector 15.

  Since the level detector 15 has a filter characteristic, it has a transient characteristic corresponding to the amplitude of the input intermediate frequency signal. Since the Wireless-USB symbol has a no-signal section of 70 nS, the level detector 15 cannot detect the correct level near the start of the signaled section due to the influence of transient characteristics.

  For this reason, it is preferable that the level detector 15 detects the level of the intermediate frequency at the timing when the transient characteristic period has elapsed from the start of the signaled section.

  As shown in FIG. 7, the stable timing output unit 42 detects the level of the intermediate frequency at the level detector 15 at the timing when the transient characteristic period corresponding to the amplitude of the intermediate frequency signal has elapsed from the start of the signal period. It is supposed to let you.

  As described above, the radio reception apparatus 41 according to the present embodiment causes the level detector 15 to detect the level of the intermediate frequency at a stable timing when the transient characteristic period of the level detector 15 has elapsed. The gain of the gain amplifier 14 can be adjusted appropriately.

1 is a block diagram illustrating a wireless reception device according to a first embodiment of this invention. It is a conceptual diagram for demonstrating operation | movement of each part of the radio | wireless receiver of the 1st Embodiment of this invention. It is a block diagram which shows the radio | wireless receiver of the 2nd Embodiment of this invention. It is a frame block diagram which shows the frame structure of Wireless-USB. It is a block diagram which shows the radio | wireless receiver of the 3rd Embodiment of this invention. It is a block diagram which shows the radio | wireless receiver of the 4th Embodiment of this invention. The level of the intermediate frequency signal converted by the frequency converter constituting the wireless receiver of the fourth embodiment of the present invention, the level detected by the level detector, and the timing indicated by the stable timing output unit It is a timing chart which shows.

Explanation of symbols

1, 21, 31, 41 Wireless receiver 10 Antenna 11 Low noise amplifier 12 Local transmitter 13 Frequency converter 14 Intermediate frequency variable gain amplifier 15 Level detector 16 Hopping control unit 17a to 17c Level storage unit 18, 38 Gain setting value Calculation units 19a to 19c Gain setting value storage unit 20 Gain setting value selection unit 22 Preamble detection unit 38 Gain setting value calculation unit 42 Stability timing output unit

Claims (4)

Hopping control means for changing a center frequency for each symbol based on a frequency hopping pattern defined by the Wireless-USB standard;
A frequency conversion means for converting the received high-frequency signal into an intermediate frequency signal based on the center frequency ;
Level detecting means for detecting the level of each intermediate frequency signal converted by the frequency converting means while the frequency hopping pattern makes a round ,
Level storage means for storing the level of the intermediate frequency signal detected by the level detection means for each center frequency;
An intermediate frequency variable gain amplifier for amplifying the intermediate frequency signal;
After said pattern of frequency hopping is round, non-linear receiver including a gain adjusting means, the adjusting the gain of the intermediate frequency variable gain amplifier according to the level of the center frequency stored in said level storage means. The level detection means detects a level of a preamble symbol at the head of the frame,
The gain adjusting means adjusts the gain of the intermediate frequency variable gain amplifier for the data symbols after the preamble symbol according to the level of the preamble symbol of each center frequency stored in the level storage means. The wireless receiver according to claim 1.   The gain adjustment means adjusts the gain of the intermediate frequency variable gain amplifier for the data symbol in accordance with an average value of preamble symbol levels of each center frequency stored in the level storage means. Item 3. The wireless receiving device according to Item 2.   The radio reception apparatus according to claim 1, wherein the level detection unit detects the level of the intermediate frequency signal at a different timing for each center frequency at which the output of the intermediate frequency variable gain amplifier is stabilized.

Images