JP2006197434A - Radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus which does not deteriorate a correlating detection accuracy of a preamble signal even when a temperature fluctuation occurs and has a stable receiving quality. <P>SOLUTION: The radio communication apparatus conducts a data communication using a frame signal including the preamble signal and is provided with a radio unit 5 to receive a radio signal, a temperature detecting means 10 to detect the temperature of the radio unit 5, and a preamble correlating detector 7 to detect the received frame signal. The preamble correlating detector 7 varies its detection level based on a detection result of the temperature detecting means 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication apparatus that performs data communication using a frame signal including a preamble signal.

2. Description of the Related Art Conventionally, in a wireless communication device, a technique for performing data communication by detecting a frame signal including a preamble signal at the beginning of a modulation signal in a receiver or the like is known.
Typically, a radio communication apparatus using a frame signal detection method for receiving a burst radio signal in which a preamble signal is added to the head of a modulated packet signal modulated by an orthogonal frequency division multiplexing (OFDM) modulation method is used. Yes.

  In recent years, wireless communication devices such as wireless LANs have begun to spread rapidly not only to companies but also to general households because of the convenience of moving terminals freely. Wireless LAN standards include IEEE802.11b using the 2.4 GHz band, IEEE802.11g, and IEEE802.11a using the 5 GHz band. The IEEE802.11b standard has already spread in the market mainly as an application for PC devices.

In these wireless standards, a burst signal, which is a training signal for synchronization called a preamble signal, is added to the beginning of a modulated signal for transmission. Many of the wireless communication devices start receiving a frame signal using a received signal strength as a trigger, or start receiving a frame signal by detecting the preamble signal described above.
That is, when the received signal level is small, the SNR (reception quality) is deteriorated, and the determination of the start point of the frame signal may be wrong only by determining the received signal strength. For this reason, the reception signal strength trigger threshold is set higher than the noise level so as to obtain sufficient determination accuracy. A signal whose reception signal level is small and smaller than the reception signal strength trigger threshold is adapted to detect the preamble signal and start frame reception.

Note that the preamble signal used in the above-described wireless standard is a signal having a repetitive pattern, and is often used as a signal for performing synchronization timing adjustment and frequency deviation correction.
Many of the wireless communication devices are provided with a preamble correlation detector for detecting a preamble signal. As the preamble correlation detector, an autocorrelation method or a cross-correlation method is used.

On the other hand, Patent Document 1 discloses a technique for correcting distortion of a transmission signal (output signal) in a wireless device based on a detection result of a temperature sensor provided in a feedback circuit.
Patent Document 2 and the like disclose a technique for reducing phase noise by removing noise included in a temperature compensation voltage at the start of power supply to the oscillator in an oscillator wireless communication device provided with a temperature compensation circuit. ing.

JP-A-9-172336 Japanese Patent Laid-Open No. 2001-230630

  The above-described conventional wireless communication apparatus has a problem that when the received signal level is reduced due to thermal noise accompanying a temperature rise, the SNR (reception quality) is deteriorated and the correlation detection accuracy (detection level) of the preamble signal is deteriorated. was there.

  Specifically, in a wireless communication device, a baseband IQ signal generated via an antenna, an amplifier, a frequency conversion unit, an orthogonal conversion unit, etc. is converted into a radio signal (or a radio signal is converted into a baseband IQ signal). Wireless unit (RF unit) is provided. The characteristics of the wireless unit may change depending on its temperature. For example, when the power amplifier (PA) or the like loses linearity in the output signal due to temperature, errors such as phase noise and frequency deviation occur in the frequency conversion unit and the orthogonal conversion unit. In addition, the degree of thermal noise also varies with temperature, and the noise level increases as the temperature rises.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a wireless communication apparatus with stable reception quality in which the correlation detection accuracy of a preamble signal does not deteriorate even when a temperature change occurs.

  According to a first aspect of the present invention, there is provided a wireless communication apparatus that performs data communication using a frame signal including a preamble signal, the wireless unit receiving a wireless signal, and the temperature of the wireless unit And a preamble correlation detector for detecting the received frame signal, the preamble correlation detector varying the detection level based on the detection result of the temperature detection means. .

  According to a second aspect of the present invention, in the wireless communication device according to the first aspect, the preamble correlation detector increases the detection level when the temperature of the wireless unit is high. .

  According to a third aspect of the present invention, there is provided the wireless communication apparatus according to the second aspect, wherein the preamble correlation detector sets the detection level when the temperature of the wireless unit becomes a predetermined value or more. It's something that gets bigger.

  According to a fourth aspect of the present invention, the wireless communication apparatus according to the first or second aspect of the present invention stores the conversion table related to the detection level with respect to the temperature of the wireless unit, and detects the preamble correlation. The device determines the detection level based on the conversion table from the detection result of the temperature detection means.

  According to a fifth aspect of the present invention, in the wireless communication device according to any one of the first to fourth aspects, the wireless unit transmits a baseband IQ signal or a wireless signal to a wireless signal or a baseband. The signal is converted into an IQ signal.

  A radio communication apparatus according to a sixth aspect of the present invention is the radio communication apparatus according to any of the first to fifth aspects, wherein the preamble signal is arranged at the head of the modulation signal.

  A radio communication apparatus according to a seventh aspect of the present invention is the radio communication apparatus according to any one of the first to sixth aspects, further comprising a demodulator that demodulates the baseband IQ signal.

  According to an eighth aspect of the present invention, there is provided a radio communication apparatus according to any one of the first to seventh aspects, further comprising a modulation unit that modulates a baseband IQ signal.

  In the present invention, the detection level of the preamble correlation detector is changed according to the temperature of the wireless unit at the time of reception. As a result, it is possible to provide a radio communication apparatus with stable reception quality in which the correlation detection accuracy of the preamble signal does not deteriorate even if temperature fluctuation occurs.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
1 and 2, the first embodiment of the present invention will be described in detail.
FIG. 1 is a configuration diagram showing a wireless communication device 1 of the IEEE 802.11a standard.
As shown in FIG. 1, the wireless communication device 1 mainly includes an antenna 2, a low noise amplifier 4, a power amplifier 3, a wireless unit 5 (also referred to as RFIC or RF unit), a baseband unit 6 (baseband LSI), It comprises a temperature sensor 10 as temperature detecting means. The baseband unit 6 is provided with a modulation unit 8 and a demodulation unit 9 as data modulation / demodulation units, and a preamble correlation detector 7.

  At the time of reception, when a radio signal is received from the antenna 2, the radio signal is input to the radio unit 5 through the power amplifier 3. The radio signal is converted into a baseband IQ signal by the radio unit 5. This baseband IQ signal includes a frame signal having a preamble signal arranged at the head.

  Thereafter, the baseband IQ signal is input to the preamble correlation detector 7 of the baseband unit 6. When the preamble signal is detected by the preamble correlation detector 7 and it is determined that the intensity of the preamble signal is greater than a predetermined detection level (correlation threshold), frame reception is started. Then, the modulation unit 8 modulates the baseband IQ signal.

  On the other hand, during communication, the baseband IQ signal demodulated by the demodulator 9 of the baseband unit 6 is input to the wireless unit 5. The baseband IQ signal is converted into a radio signal by the radio unit 5, and the converted radio signal is radiated from the antenna 2 through the low noise amplifier 4.

  Here, the wireless communication device 1 according to the first embodiment is provided with a temperature sensor 10 that detects the temperature of the wireless unit 5 (or the vicinity thereof). The detection result (the temperature information of the wireless unit 5) detected by the temperature sensor 10 is transmitted to the preamble correlation detector 7. Then, in the preamble correlation detector 7, the detection level (correlation threshold value) for the preamble signal is varied based on the transmitted temperature information.

  Specifically, referring to FIG. 2, when the temperature sensor 10 detects that the temperature of the wireless unit 5 is equal to or higher than a predetermined value T1, the correlation threshold is increased from V0 to V1. As a result, even when the wireless unit 5 becomes hot and the noise level rises, the SNR in the preamble correlator 7 decreases, causing false detection due to noise, or receiving a frame signal with poor reception quality. The malfunction that is done is suppressed. That is, as the temperature of the wireless unit 5 rises, the detection level of the preamble correlation detector 7 is increased, so that the SNR is stabilized and the frame signal in which packet errors frequently occur is not easily detected.

  As described above, in the first embodiment, the detection level of the preamble correlation detector 7 is changed according to the temperature of the radio unit 5 at the time of reception. As a result, it is possible to provide the wireless communication device 1 with stable reception quality in which the correlation detection accuracy of the preamble signal does not deteriorate even if temperature fluctuation occurs.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 3 is a cross-sectional view showing wireless communication apparatus 1 according to the second embodiment, which corresponds to FIG. 1 of the first embodiment. The wireless communication device 1 of the second embodiment is different from that of the first embodiment in that a conversion table relating to the detection level with respect to the temperature of the wireless unit 5 is stored.

  As shown in FIG. 3, in the second embodiment, a memory storing a correlation threshold table (conversion table) 11 indicating the relationship between the temperature of the wireless unit 5 and the detection level (correlation threshold) is stored in the baseband unit 6. is set up. The correlation threshold value table 11 is a table showing the relationship between the temperature of the wireless unit 5 and the correlation threshold value as shown in FIG. Then, based on the correlation threshold value table 11 from the result of the temperature sensor 10, the correlation threshold value in the preamble correlation detector 7 is determined.

Specifically, referring to FIG. 4, when the temperature sensor 10 detects that the temperature of the wireless unit 5 is T2, the detection result is transmitted to the correlation threshold table 11 and the correlation threshold table 11 Based on this, the correlation threshold is set to V2. As a result, even when the wireless unit 5 becomes hot and the noise level rises, the SNR in the preamble correlator 7 decreases, causing false detection due to noise, or receiving a frame signal with poor reception quality. The malfunction that is done is suppressed.
In particular, in the second embodiment, even if the relationship between the temperature and the detection level is non-linear, variable control of the detection level can be simplified by using the conversion table 11.

  As described above, also in the second embodiment, the detection level of the preamble correlation detector 7 is changed according to the temperature of the wireless unit 5 at the time of reception. As a result, it is possible to provide the wireless communication device 1 with stable reception quality in which the correlation detection accuracy of the preamble signal does not deteriorate even if temperature fluctuation occurs.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

It is a block diagram which shows the radio | wireless communication apparatus in Embodiment 1 of this invention. It is a graph which shows the relationship between the temperature of a wireless unit, and a detection level. It is a block diagram which shows the radio | wireless communication apparatus in Embodiment 2 of this invention. It is a graph which shows the relationship of the detection level with respect to the temperature of a wireless unit.

Explanation of symbols

1 wireless communication device,
2 antenna, 3 power amplifier, 4 low noise amplifier,
5 Wireless unit (RF unit),
6 Baseband part,
7 Preamble correlation detector, 8 Modulator, 9 Demodulator,
10 Temperature sensor (temperature detection means),
11 Correlation threshold table (conversion table).

Claims (8)

A wireless communication device that performs data communication using a frame signal including a preamble signal,
A radio unit for receiving radio signals;
Temperature detecting means for detecting the temperature of the wireless unit;
A preamble correlation detector for detecting the received frame signal;
The radio communication apparatus characterized in that the preamble correlation detector varies its detection level based on a detection result of the temperature detection means. The wireless communication apparatus according to claim 1, wherein the preamble correlation detector increases the detection level when the temperature of the wireless unit is high. The radio communication apparatus according to claim 2, wherein the preamble correlation detector increases the detection level when a temperature of the radio unit becomes a predetermined value or more. Storing a conversion table related to the detection level with respect to the temperature of the wireless unit;
The radio communication apparatus according to claim 1, wherein the preamble correlation detector determines the detection level based on the conversion table based on a detection result of the temperature detection unit. The wireless communication apparatus according to claim 1, wherein the wireless unit converts a baseband IQ signal or a wireless signal into a wireless signal or a baseband IQ signal. The radio communication apparatus according to claim 1, wherein the preamble signal is arranged at the head of a modulation signal. The radio communication apparatus according to claim 1, further comprising a demodulator that demodulates the baseband IQ signal. The radio communication apparatus according to claim 1, further comprising a modulation unit that modulates a baseband IQ signal.

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