JP2008118195A - Channel scanning method and wireless communication system using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve performance of an upper layer in channel scanning operation. <P>SOLUTION: When a reception signal Sin received from a wireless signal having a plurality of channels is input, a mixer 2 selects a physical reception channel based on the number of channels set by the upper layer 20 to find a base band signal S2. A demodulation processing section 3 demodulates the base band signal S2 to judge whether a desired transmission signal is included in the reception channel. Reception channels are changed in order under the control of a control section 4 based on the judgment processing result to perform judgment processing on all the channels, all judgment processing results are held in a table 5, and the completion of the judgment processing is notified to the upper layer 20. Further, a variable filter 1 adjusts the frequency of the reception signal Sin in conjunction with the change of the reception channels, so that receiving performance is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention inputs a received signal received from a radio wave (wireless signal) having a plurality of channels in digital terrestrial broadcasting, wireless LAN (Local Area Network), etc., and to which channel the transmission signal is output. And a radio communication system using the same.

  Conventionally, in a radio communication system such as a digital broadcast receiving apparatus having a plurality of reception channels, a reception signal received from a radio signal having a plurality of channels is input, and it is detected to which channel a transmission signal is output. As a technique related to the channel scanning method, for example, there is a technique described in the following documents.

JP 2003-60486 A JP 2004-179928 A JP 2004-363806 A

  As described in Patent Documents 1 to 3 and the like, when confirming to which channel a desired transmission signal is transmitted, an upper layer (for example, a media access control layer (Media Access Control Layer (Media Access Control Layer)) is determined for each channel. Control layer; hereinafter referred to as “MAC layer”) for a plurality of circuit functions, and after the control setting, as a process of the upper layer, a desired transmission signal is transmitted to the lower layer within a predetermined time. It is necessary to always check whether it comes up from the physical layer, that is, it is necessary to perform handshake with the physical layer (handshake, one of the communication methods that start transmission after a confirmation signal is returned). there were.

  However, the conventional channel scanning method has the following problems (a) and (b).

  (A) An upper layer such as a MAC layer must individually set each circuit function for each channel for which channel search (search) is performed, or even after setting, always check for the presence of a desired transmission signal. The upper layer needs a lot of processing time for the channel search. For this reason, the processing capability (performance) of the upper layer is reduced.

  (B) When each circuit function is controlled and set for each channel from the upper layer, data writing cannot be performed in parallel. Therefore, particularly when a plurality of channels are detected, and in terms of the configuration of the circuit system, a plurality of When data must be set for this circuit function, the detection time becomes longer.

  In the channel scan method of the present invention, a reception signal received from a radio signal having a plurality of channels is input, and a physical reception channel is selected from the reception signal based on the number of detection target channels set by an upper layer. The baseband signal is obtained, and the baseband signal is demodulated to determine whether or not a desired transmission signal is included in the reception channel. Based on the processing result of the determination processing, the reception channel is determined. All the determination processes for the number of channels are performed in order, the processing results of all the determination processes are held, and the completion of all the determination processes is notified to the upper layer.

  The wireless communication system of the present invention includes a tuner unit, a demodulation processing unit, a holding unit, and a control unit.

  The tuner unit receives a reception signal received from a radio signal having a plurality of channels, and selects a physical reception channel from the reception signal based on the number of detection target channels set by an upper layer. A band signal is obtained. The demodulation processing unit demodulates the baseband signal and determines whether or not a desired transmission signal is included in the reception channel. The holding unit holds a result of the determination process and is read by the upper layer. Further, the control means sequentially changes the reception channel based on the processing result of the determination process to perform all the determination processes for the number of channels, and causes the holding means to process all the determination processes. And holding the completion of all the determination processes to the upper layer.

  According to the channel scan method of the present invention and the radio communication system using the same, the channel scan operation is automatically performed in accordance with the instruction from the upper layer, and when the channel scan operation is completed, the completion is notified to the upper layer. As a result, the processing amount of the upper layer can be reduced, and the performance of the upper layer can be improved during the channel scan operation.

  Further, when the frequency of the reception signal is adjusted in conjunction with the change of the reception channel, the frequency characteristics are adjusted when the channel is changed, so that the reception performance can be improved.

  A channel scanning method of a wireless communication system inputs a received signal received from a radio signal having a plurality of channels, and based on the number of channels to be detected set by an upper layer (for example, a MAC layer), from the received signal A physical reception channel is selected to obtain a baseband signal. The baseband signal is demodulated to determine whether or not a desired transmission signal is included in the reception channel. Then, based on the processing results of the determination processes, the reception channels are sequentially changed to perform all the determination processes for the number of channels, hold the processing results of all the determination processes, and perform all the determination processes. The completion is notified to the upper layer.

(Configuration of Example 1)
FIG. 1 is a schematic configuration diagram of a wireless communication system showing a first embodiment of the present invention.

  This wireless communication system is a physical layer (for example, a terrestrial digital broadcast receiving device) controlled by an upper layer 20 (for example, a MAC layer), and has a plurality of channels of wireless signals (for example, orthogonal frequency multiplex modulation (hereinafter referred to as orthogonal frequency multiplex modulation). The reception signal Sin received from the broadcast wave (which is referred to as “OFDM”) is input, and frequency adjustment means (for example, a variable filter including an LC filter) 1 that adjusts the frequency of the reception signal Sin is provided. A tuner unit (for example, a mixer which is a mixer) 2 is connected to the output side via an automatic gain control circuit (hereinafter referred to as “AGC circuit”) not shown. The mixer 2 is a circuit that obtains an analog baseband signal S2 by selecting a physical channel (that is, a physical reception channel) from the reception signal Sin based on the number CH_NUMBER of detection target channels set by the upper layer 20. The demodulation processing unit 3 is connected to the output side via a band pass filter (BPF), an AGC circuit, and the like (not shown).

  The demodulation processing unit 3 converts the analog baseband signal S2 into a digital baseband signal, and then demodulates the analog baseband signal S2 by a fast Fourier transform (hereinafter referred to as “FFT conversion”) to output a transport stream signal TS. Is a circuit that performs a process of determining whether or not a desired transmission signal is included, and outputs a signal detection determination signal S3 that is a result of the determination process. The output side of the demodulation processing unit 3 is accessed by the upper layer 20, and a control unit (for example, control unit) 4 that controls the channel scan operation and a holding unit (for example, signal detection determination holding) that holds the signal detection determination result. Table) 5, and a timer 6 is connected to the control unit 4 and the table 5. The control unit 4, the table 5, the timer 6, and the upper layer 20 are connected to each other by a bus (not shown).

  The control unit 4 receives the signal detection determination signal S3, and scans the channel number (start scan channel number START_SCAN_CH_NUMBER and end scan channel number STOP_SCAN_CH_NUMBER) set by the upper layer 20 from the upper layer 20 (CH_SCAN). ) A function of outputting a start enable signal START_EN and the number of channels CH_NUMBER and giving a channel scan (CH_SCAN) completion signal S4 to the upper layer 20 in order to change the order in response to the start request S24 and perform the determination processing. Have.

  The signal detection determination holding table 5 receives the signal detection determination signal S3, the start enable signal START_EN, the channel number CH_NUMBER, and the timer (timer) expiration report signal S6 from the timer 6, holds the signal detection determination result, and the channel (CH) has a function of outputting the presence / absence information signal S5 and giving it to the upper layer 20. The timer 6 has a detection time set value S23 set by the upper layer 20, starts a time measuring operation based on the start enable signal START_EN, outputs a timer (timer) expiration report signal S6, and holds the control unit 4 and the signal detection determination This is a circuit given to the table 5.

  On the output terminal side of the start enable signal START_EN and the number of channels CH_NUMBER in the control unit 4, a phase locked loop (hereinafter referred to as "PLL") data table 7 for setting a frequency and a pulse for setting a voltage value A width modulation (hereinafter referred to as “PWM”) data table 10 is connected. The control input terminal of the mixer 2 is fed back to the output side of the PLL data table 7 via a data generator 8 composed of a voltage controlled oscillator (hereinafter referred to as “VCO”) and a PLL circuit 9. Back) connected. On the output side of the PWM data table 10, a control input terminal of the variable filter 1 is connected via a PWM generator 11 for generating a PWM pulse composed of a VCO or the like and a primary filter 12 composed of an RC filter. The feet are connected back.

FIG. 2 is a configuration diagram showing an outline of a main part of the demodulation processing unit 3 in FIG.
The demodulation processing unit 3 converts an analog baseband signal S2 output from the mixer 2 into a digital baseband signal by an analog / digital converter (hereinafter referred to as “ADC”) 3a, and this digital baseband signal. The signal is subjected to frequency variation correction and symbol timing correction by an auto frequency control / symbol timing recovery (hereinafter referred to as “AFC / STR”) circuit 3b. The corrected digital baseband signal is subjected to FFT conversion by the FFT unit 3c, and then demodulated by transmission and multiplexing control (hereinafter referred to as "TMCC") to be a pilot signal. A configuration for outputting a TMCC demodulated signal, demodulating a Reed-Solomon (hereinafter referred to as “RS”) code, which is an error correction code, after performing Viterbi decoding and the like, and outputting a transport stream signal TS It has become.

  Here, as the signal detection determination signal S3, for example, an STR signal, a TMCC demodulated signal, or an RS demodulated signal can be used. As reliability, STR signal <TMCC demodulated signal <RS demodulated signal, and the detection time is reversed, and STR signal> TMCC demodulated signal> RS demodulated signal.

FIG. 3 is a schematic configuration diagram showing the PLL data table 7 in FIG.
The PLL data table 7 includes a data storage area 7a in which PLL data that is a frequency setting value corresponding to a physical channel (for example, 13CH to 62CH) is stored, and a selector 7b connected to the output side. ing. Then, the PLL data is read from the data storage area 7a by the start enable signal START_EN given from the control unit 4, and this read data is selected by the selector 7b by the channel number CH_NUMBER given from the control unit 4. It is configured to output.

FIG. 4 is a schematic configuration diagram showing the PWM data table 10 in FIG.
The PWM data table 10 includes a data storage area 10a in which PWM data, which is a voltage setting value corresponding to a physical channel (for example, 13CH to 62CH), and a selector 10b connected to the output side. ing. Then, PWM data is read from the data storage area 10a by the start enable signal START_EN given from the control unit 4, and the read data is selected by the selector 10b by the number of channels CH_NUMBER given from the control unit 4. It is configured to output.

FIG. 5 is a schematic configuration diagram showing the primary filter 12 in FIG.
The primary filter 12 is a circuit that outputs a DC voltage by smoothing the PWM pulse output from the PWM generator 11, and includes a resistor 12a and a capacitor 12b.

(Channel Scanning Method of Example 1)
6A and 6B are flowcharts illustrating the processing procedure of the channel scan method in the wireless communication system of FIG.

  In this channel scan process, first, the upper layer 20 sets the number of channels (CH) to be detected as an initial setting (step ST1). For example, if you want to detect signals for 5CH channels from 20CH to 25CH, START_SCAN_CH_NUMBER value is set to 20 for the control unit 4 with the start scan channel number S21, and STOP_SCAN_CH_NUMBER value is set with the stop scan channel number S22. = 25CH is set. If the maximum signal detection time of 1CH is to be set to 1 msec, for example, the detection time setting value setting = 1 msec is set for the timer 6 by the detection time setting value S23.

  After setting the above parameters, the upper layer 20 instructs the control unit 4 to perform a channel scan (CH_SCAN) start request S24 (step ST2), thereby starting a channel scan (scan) operation (steps ST3 to ST13). ) Until the upper layer 20 receives the channel scan (CH_SCAN) completion signal S4 from the control unit 4 (step ST14), it is not particularly necessary to give an instruction to the receiving device or confirm the presence or absence of the signal. After receiving the channel scan (CH_SCAN) completion signal S4 from the control unit 4, the upper layer 20 checks the signal detection determination holding table 5 and determines which channel (CH) has a desired transmission signal. It is possible to confirm the presence or absence of a desired transmission signal simply by confirming.

  After receiving the channel scan (CH_SCAN) start request S24 from the upper layer 20 (step ST2), the control unit 4 of the receiving apparatus operates without control of the upper layer 20 as follows (steps ST3 to ST14).

  The configuration of this receiving apparatus assumes a state in which a received signal Sin of a wireless communication system is in a high band and a plurality of channels configured in the received signal Sin are simultaneously transmitting continuous signals. It is what. Normally, when the reception channel is changed, the data setting of the PLL circuit 9 related to the local frequency, the data generator 8 composed of the VCO, etc. may be performed. In the reception signal Sin of the system, the reception performance is improved by changing the frequency characteristic of the variable filter 1 by the output signal of the PLL circuit 9.

  The configuration of this receiving apparatus has a data storage table (for example, a PLL data table 7 and a PWM data table 10) corresponding to a channel (CH) for each PLL function and PWM function. As described above, the number of channels CH_NUMBER (n = m, m + 1,...) Output from the control unit 4 is used (steps ST4 and ST12). The PLL data and PWM data of the table values are obtained for each function when the start enable signal START_EN output from the control unit 4 changes from logic “0” to logic “1” (steps ST13, ST4 to ST7). Each table value is reflected in conjunction. From that time point, the timer 6 for measuring the signal detection time starts to operate until the timer (timer) value reaches the same time as the detection time setting value S23 set in the initial setting (steps ST7 to ST10). Signal detection (determination process in step ST8) is executed. Note that the first channel for signal detection is the value of the number of start scan channels (START_SCAN_CH_NUMBER) S21 (m = 0 in step ST3).

  If no signal is detected even when the timer expires (YES in step ST10), the number of channels CH_NUMBER output from the control unit 4 is changed to detect the next channel (CH) (step ST12). , ST13 (n = m + 1), the start enable signal START_EN is output again from the control unit 4 (step ST7). Similarly, a table value for each function indicated by the number of channels CH_NUMBER (= n) is reflected as a setting value for each function (step ST7). At this time, the signal detection determination holding table 5 stores the number of channels CH_NUMBER that could not be detected and the absence of a transmission signal (step ST11).

  Conversely, if a desired transmission signal is detected even if the timer does not expire (step ST8), the number of detected channels CH_NUMBER and the transmission signal exist in the signal detection determination holding table 5. Is stored (step ST11).

  Then, similarly to the case where the signal is not detected, the control unit 4 outputs the number of channels CH_NUMBER and the start enable signal START_EN so that the signal of the next channel (CH) can be detected (steps ST12, ST13, ST4˜). ST7).

  After the signal detection as described above is performed for the entire channel (CH) range specified by the upper layer 20 (YES in step ST12), the channel scan (CH_SCAN) is performed on the upper layer 20 from the control unit 4. A completion signal S4 is output (step ST14), and a series of channel scan operations are completed.

(Effect of Example 1)
Compared with the method in which the upper layer 20 controls the receiving apparatus for each channel and confirms the signal detection result as the channel scan operation, according to the channel scan method of the first embodiment, the channel scan from the upper layer 20 ( The receiving apparatus that has received the CH_SCAN) start request S24 automatically performs a channel scan operation. When this channel scan operation is completed, a channel scan (CH_SCAN) completion signal S4 is provided to the upper layer 20. Therefore, the processing amount of the upper layer 20 can be reduced, and the performance of the upper layer 20 can be improved during the channel scan operation. Moreover, since the frequency characteristics of the variable filter 1 are changed in conjunction with the channel change, the reception performance can be improved.

(Modification)
The present invention is not limited to the first embodiment, and various usage forms and modifications are possible. For example, the configuration of the receiving apparatus illustrated in FIGS. 1 and 2 can be changed to a configuration other than that illustrated, and the processing procedure of the channel scanning method illustrated in FIGS. It can be changed to another processing procedure. Further, the channel scan method of the present invention is not limited to the digital terrestrial broadcast receiving apparatus as in the first embodiment, and can be applied to other wireless communication systems such as a wireless LAN.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the radio | wireless communications system which shows Example 1 of this invention. It is a block diagram which shows the outline | summary of the principal part in the demodulation process part 3 in FIG. It is a schematic block diagram which shows the PLL data table 7 in FIG. It is a schematic block diagram which shows the table 10 for PWM data in FIG. It is a schematic block diagram which shows the primary filter 12 in FIG. 3 is a flowchart showing a processing procedure of a channel scanning method in the wireless communication system of FIG. 1. 3 is a flowchart showing a processing procedure of a channel scanning method in the wireless communication system of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable filter 2 Mixer 3 Demodulation processing part 4 Control part 5 Signal detection determination holding table 6 Timer 7 PLL data table 10 PWM data table 20 Upper layer

Claims (6)

Input a reception signal received from a radio signal having a plurality of channels, and based on the number of channels to be detected set by the upper layer, select a physical reception channel from the reception signal to obtain a baseband signal,
The baseband signal is demodulated to determine whether or not a desired transmission signal is included in the reception channel,
Based on the processing result of the determination process, the reception channels are sequentially changed to perform all the determination processes for the number of channels, hold the processing results of all the determination processes, and complete the determination processes. A channel scan method characterized by notifying an upper layer.   2. The channel scanning method according to claim 1, wherein when the determination process does not end within the detection time set by the upper layer, the channel is changed to the next reception channel.   3. The baseband signal is obtained by adjusting the frequency of the reception signal in conjunction with the change of the reception channel, and selecting the reception channel from the reception signal of the adjusted frequency. Channel scanning method. A tuner that receives a received signal received from a radio signal having a plurality of channels and selects a physical received channel from the received signal based on the number of detection target channels set by an upper layer to obtain a baseband signal And
A demodulation processing unit that demodulates the baseband signal and determines whether or not a desired transmission signal is included in the reception channel;
Holding means for holding the processing result of the determination process and being read by the upper layer;
Based on the processing results of the determination processing, the reception channels are sequentially changed to perform all the determination processing for the number of channels, and the processing results of all the determination processing are held in the holding unit and all the determinations are performed. Control means for notifying the upper layer of completion of processing;
A wireless communication system comprising:   5. The radio communication system according to claim 4, wherein the control means changes to the next reception channel when the determination process is not completed within a detection time set by the higher layer. The wireless communication system according to claim 4 or 5, further comprising:
A radio communication system comprising frequency adjusting means for adjusting the frequency of the reception signal in conjunction with the change of the reception channel and inputting the reception signal of the adjusted frequency to the tuner unit.

Images