JP4077255B2 - Wireless communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless communication apparatus that performs In Sync (establishment of synchronization) determination and Out of Sync (out of synchronization) determination for confirmation of a synchronization state.
[0002]
[Prior art]
In a W-CDMA (Wideband Code Division Multiple Access) type mobile radio communication system, In Sync determination and Out of Sync determination are performed at the mobile radio communication terminal in order to manage the synchronization state between the mobile radio communication terminal and the base station. Every frame, the determination result is reported from the mobile radio communication terminal to the base station.
[0003]
The criteria for determining the synchronization status are defined in two different phases:
[0004]
The first phase continues until 160 ms after the establishment of the downlink dedicated channel is confirmed by the upper layer. In the first phase, only In Sync determination is performed, and Out of Sync determination and reporting are not performed. In the In Sync determination, if the DPCCH (Dedicated physical control channel) Quality for the previous 40 ms is better than the threshold value Qin, it is determined as In Sync and notified to the upper layer.
[0005]
The second phase is started 160 ms after the establishment of the downlink dedicated channel is confirmed by the upper layer. In this second phase, it is determined as Out of Sync when any of the following conditions is satisfied.
[0006]
(1) The DPCCH Quality for the last 160 ms is worse than the threshold value Qout.
[0007]
(2) The CRC (Cyclic Redundancy Check) of the latest 20 transport blocks received in all the transport channels being received are all errors, and all the CRCs of the transport blocks received in the previous 160 ms are all error.
[0008]
In addition, when all of the following conditions are satisfied, it is determined as In Sync.
[0009]
(1) The DPCCH Quality for the last 160 ms is better than the threshold value Qin.
[0010]
(2) In all transport channels being received, at least one transport block is received by CRC OK within a TTI (Transmission Time Interval) including the current frame.
[0011]
In this way, the synchronization determination is performed. When it is determined that Out of Sync, the transmitter is stopped. After that, when it is determined that In Sync, the transmitter is restarted.
[0012]
On the other hand, in this type of mobile radio communication terminal, it is checked whether there is an adjacent channel band signal in order to determine the necessity of handoff or the like. This confirmation can be performed by notification from the base station side through the broadcast channel.
[0013]
[Problems to be solved by the invention]
As described above, in the In Sync determination and the Out of Sync determination, the DPCCH output quality threshold values Qin and Qout are compared. Here, the DPCCH output is subjected to suppression of adjacent channel band signals by the roll-off filter. Later. For this reason, when there is a sufficiently large output in the adjacent channel band, the DPCCH output after applying the roll-off filter becomes small. In this case, even if the desired signal is output that does not originally become Out of Sync, it may be erroneously determined as Out of Sync. Even if the desired signal is an output that should be determined as In Sync, there is a possibility that it is not determined as In Sync.
[0014]
Also, when checking whether or not there is an adjacent channel band signal based on notification from the base station side, notification data on the broadcast channel must be extracted and analyzed. For this reason, it takes a lot of time for confirmation.
[0015]
The present invention has been made in consideration of such circumstances, and the object of the present invention is firstly to determine the establishment of synchronization or loss of synchronization more accurately while minimizing the influence of the signal component of the adjacent channel band. An object of the present invention is to provide a wireless communication apparatus capable of performing the above.
[0016]
A second object of the present invention is to provide a wireless communication apparatus capable of confirming whether or not an adjacent channel band signal exists in a short time.
[0017]
[Means for Solving the Problems]
In order to achieve the first object, the present invention provides a first determination condition in which a reception quality value related to a first channel through which a signal always arrives during communication is better than a first threshold. Based on the second determination condition, and one of the conditions is that the reception quality value is worse than a second threshold value different from the first threshold value. A wireless communication device comprising synchronization determining means for determining that the wireless communication device is in a state; a receiving means for receiving a wireless signal; and a second channel different from the first channel in the wireless signal received by the receiving means Filter means for suppressing signal components in a band other than the first band, and signal components in a channel band adjacent to the second channel based on respective power values of an input signal and an output signal of the filter means. A calculation means for calculating a value indicating a ratio of the magnitude in the radio signal, and a first standard threshold value and a predetermined first threshold value so as to decrease as the value calculated by the calculation means decreases. Correction means for correcting the standard threshold value of 2 to obtain the first threshold value and the second threshold value.
[0018]
By taking such measures, synchronization is performed based on a first determination condition in which one of the conditions is that the reception quality value related to the first channel through which a signal always arrives during communication is better than the first threshold value. It is determined that it is in a state, and it is determined that it is out of synchronization based on a second determination condition where one of the conditions is that the reception quality value is worse than a second threshold value different from the first threshold value. However, the first threshold value and the second threshold value are the first standard threshold value and the second standard threshold value depending on the magnitude of the signal component of the adjacent channel band of the second channel in the received signal. It is obtained adaptively by correcting. Therefore, it is determined whether the synchronization state and the out-of-synchronization state are based on an appropriate threshold according to the actual communication status.
[0019]
In order to achieve the second object, the present invention further includes an adjacent method for determining the presence / absence of an adjacent channel of the second channel based on whether the value calculated by the calculating unit is equal to or greater than a threshold value. A channel detection means is provided in the wireless communication apparatus.
[0020]
By taking such means, the presence / absence of an adjacent channel is determined based on the magnitude of the signal component of the adjacent channel band of the second channel included in the received signal. Therefore, the presence / absence of an adjacent channel is determined from the state of the received signal before the demodulation process.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a block diagram showing a main configuration of a mobile radio communication terminal according to the present embodiment.
[0023]
This mobile radio communication terminal is used in a W-CDMA mobile radio communication system, and implements mobile communication by communicating with a base station (not shown) by the W-CDMA system.
[0024]
As shown in this figure, the mobile radio communication terminal of this embodiment includes an antenna 1, an analog front end 2, an A / D converter 3, a roll-off filter 4, a searcher 5, despreaders 6-1, 6-2,. , 6-n-1, 6-2..., 6-n, a symbol synthesizer 7 and a control unit 8.
[0025]
A radio signal transmitted from the base station is received by the antenna 1 and converted into a baseband by the analog front end 2.
[0026]
The baseband received signal obtained by the analog front end 2 is sampled by the A / D converter 3 at a predetermined sampling rate. The received signal sampled by the A / D converter 3 is suppressed by the roll-off filter 4 in the signal power other than the desired signal band, that is, the signal power of the adjacent channel. The received signal that has passed through the roll-off filter 4 is input to the searcher 5 and the despreaders 6-1, 6-2,.
[0027]
The searcher 5 performs a PN search on a pilot signal constantly transmitted from the base station, and basically has the same configuration as a despreader. The power information obtained by the PN search of this path search unit is given to the control unit, and is used for searching for a path having a large power, that is, a path to be a reception path.
[0028]
Each of the despreaders 6-1, 6-2, ..., 6-n despreads the received signal that has passed through the roll-off filter 4 and demodulates the data. The despreaders 6-1, 6-2,..., 6-n perform demodulation on the reception path assigned by the control unit 8 among the multiple multipaths.
[0029]
Each symbol data demodulated by the despreaders 6-1, 6-2,..., 6-n is input to the symbol synthesizer 7. The symbol synthesizer 7 synthesizes the integrated outputs of the received signals output from the despreaders 6-1, 6-2,.
[0030]
The control unit 8 includes, for example, a microprocessor as a main control circuit, and performs overall control of each unit so as to realize an operation as a mobile radio communication terminal. The control unit 8 functions as a threshold value calculation unit 8a, a synchronization determination unit 8b, and an adjacent channel detection unit 8c in addition to performing known processing for realizing the functions of a conventional mobile radio communication terminal.
[0031]
Here, the threshold value calculation unit 8a obtains a threshold value used in In Sync determination and Out of Sync determination in consideration of the output of the A / D converter 3 and the output of the roll-off filter 4. The synchronization determination unit 8b performs In Sync determination and Out of Sync determination using the threshold obtained by the threshold calculation unit 8a. The adjacent channel detection unit 8c detects the presence / absence of an adjacent channel band signal in consideration of the output state of the A / D converter 3 and the output state of the roll-off filter 4.
[0032]
The control unit 8 exchanges a number of control signals with each unit in order to control each unit, but FIG. 1 shows only a part relating to the present invention, and omits others.
[0033]
Next, the operation of the mobile radio communication terminal configured as described above will be described.
[0034]
The received signal obtained by receiving the radio signal transmitted from the base station by the antenna 1 is processed by the analog front end 2, the A / D converter 3, and the roll-off filter 4, respectively, and then the searcher 5 and the inverse signal are processed. Input to the diffusers 6-1, 6-2, ..., 6-n, respectively. Then, the searcher 5 searches for paths based on the received signal, and demodulation of a plurality of received paths detected thereby is performed by the despreaders 6-1, 6-2,. The symbol data demodulated by the despreaders 6-1, 6-2,..., 6-n are integrated and synthesized by the symbol synthesizer 7 to reproduce the data components.
[0035]
While such a receiving operation is performed, the control unit 8 executes a process as shown in FIG. 2 for each frame.
[0036]
As shown in FIG. 2, in step ST1, the control unit 8 first calculates the average output Pri in the frame at the output of the A / D converter 3 and the average output Pro in the frame at the output of the roll-off filter 4, respectively. Ask. At this time, as the frame averages Pri and Pro, the power value is obtained using the mean square. That is, as the average output Pri, the average value within the frame of the power value in the received signal before the signal component of the adjacent channel band is removed by the roll-off filter 4 is obtained. As the average output Pro, the average value of the power values in the received signal after the signal component of the adjacent channel band is removed by the roll-off filter 4 in the frame is obtained.
[0037]
Next, in step ST2, the control unit 8 obtains the ratio k between the frame average Pri and the frame average Pro obtained as described above by the following equation.
[0038]
k = Pro / Pri
The value of the ratio k decreases when the signal component in the adjacent channel band is large, and conversely increases when the signal component in the adjacent channel band is small.
[0039]
Subsequently, in step ST3, the control unit 8 obtains a ratio Pnch between the ratio k and the reference value kc by the following equation.
[0040]
Pnch = k / kc
Here, the reference value kc is a value indicating the pass characteristic of the desired channel band in the roll-off filter 4. The reference value kc is a ratio of the frame average ProC of the input signal and the frame average ProC of the output signal when a received signal having no signal component of the adjacent channel band is input to the roll-off filter 4 by the following equation. It is a fixed constant.
[0041]
kc = ProC / PriC
Thus, the ratio Pnch represents how much the input / output power ratio of the roll-off filter 4 is deviated from the input / output power ratio of the roll-off filter 4 when there is no signal component in the adjacent channel band. A value is obtained. That is, the ratio Pnch is a value indicating the ratio of the magnitude of the signal component in the adjacent channel band.
[0042]
Therefore, in step ST4, the control unit 8 determines the correction threshold values Qin ′ and Qout ′ by correcting the standard threshold values Qin and Qout with the ratio Pnch determined as described above. Specifically, this correction is performed by calculating the following equation.
[0043]
Qin '= Pnch × Qin
Qout '= Pnch × Qout
By the way, the standard threshold values Qin and Qout are fixed threshold values determined as design values in order to perform In Sync determination and Out of Sync determination in consideration of DPCCH Quality obtained in the In Sync state and Out of Sync state, respectively. The standard threshold values Qin and Qout may change depending on a difference in operating state such as a difference in the type of data to be received. In such a case, standard threshold values Qin and Qout are determined for each condition, and the standard threshold values Qin and Qout corresponding to the actual operation state are used for the calculation in step ST4.
[0044]
Thereafter, in step ST5, the control unit 8 performs In Sync determination and Out of Sync determination. The details of this In Sync determination and Out of Sync determination follow the conventional regulations as shown in the prior art. However, the control unit 8 uses correction threshold values Qin ′ and Qout ′ instead of the threshold values Qin and Qout.
[0045]
The control unit 8 uses the results of the above In Sync determination and Out of Sync determination, for example, for controlling a transmitter (not shown). That is, for example, if it is determined that the state is the In Sync state, the transmitter is operated, and if it is determined that the state is the Out of Sync state, the transmitter is stopped.
[0046]
Next, in step ST6, the control unit 8 checks whether or not the ratio Pnch obtained in step ST3 is equal to or greater than the threshold value Qnch. The threshold value Qnch is a constant set to a value obtained by adding a certain margin to the ratio kc, for example. Therefore, if the ratio Pnch is greater than or equal to the threshold value Qnch, the ratio Pnch is greater than the ratio kc by more than the margin, and the signal component of the adjacent channel band is included in the received signal input to the roll-off filter 4 with a certain size. Will be. Therefore, if it is confirmed in step ST6 that the ratio Pnch is equal to or greater than the threshold value Qnch, the control unit 8 determines in step ST7 that there is an adjacent channel. Conversely, if it is confirmed in step ST6 that the ratio Pnch is less than the threshold value Qnch, the control unit 8 determines in step ST8 that there is no adjacent channel.
[0047]
The determination result of the presence / absence of the adjacent channel can be used as information for determining whether or not handover is necessary, for example.
[0048]
As described above, according to the present embodiment, In Sync determination and Out of Sync determination are performed using the correction threshold values Qin ′ and Qout ′ obtained by correcting the standard threshold values Qin and Qout with the ratio Pnch. For this reason, the smaller the ratio k between the frame average Pri and the frame average Pro, the lower the threshold value is used, and the larger the ratio k, the higher the threshold value is used to perform the In Sync determination and Out of Sync determination. . If there is an adjacent channel, the power value of the received signal related to DPCCH will be small, so if it remains at a fixed threshold value as in the past, it will be likely to become Out of Sync and it will be difficult to return to In Sync. Since the threshold value is lowered by increasing the ratio of the power level of the signal component of the channel band, it is difficult to become out of sync in this situation, and even if it falls into out of sync, it becomes in sync again The operation of In Sync judgment and Out of Sync judgment is adjusted to make it easier to return. As a result, the In Sync determination and the Out of Sync determination can be properly performed under conditions wider than those in the past. As a result, loss of synchronization is less likely to occur, and recovery from loss of synchronization can be performed quickly, so that synchronization can be maintained for a long time and communication with better quality can be performed.
[0049]
Further, according to the present embodiment, how much the input / output power ratio of the roll-off filter 4 is deviated from the input / output power ratio of the roll-off filter 4 when there is no signal component in the adjacent channel band. Since the presence / absence of an adjacent channel is determined according to the magnitude of the value Pnch to be represented, it is possible to determine the presence / absence of an adjacent channel earlier than completing the analysis of the notification data in the broadcast channel. As a result, it is possible to smoothly shift to an adjacent channel such as a handover, and it is possible to maintain a better communication state even during movement.
[0050]
The present invention is not limited to the above embodiment. For example, the present invention can also be applied to a wireless communication apparatus applied to a mobile wireless communication system that employs a communication method other than the W-CDMA method. Accordingly, the channel of interest for synchronization determination is not limited to the DPCCH, and may be a predetermined channel through which a signal always arrives during communication.
[0051]
Further, the present invention can be applied to a wireless communication terminal provided with another type of band pass filter instead of the roll-off filter 4.
[0052]
In addition, it is not necessary to have both In Sync determination and Out of Sync determination, and determination of the presence / absence of an adjacent channel, and it is also possible to realize a wireless communication terminal that performs either one.
[0053]
In addition, various modifications can be made without departing from the scope of the present invention.
[0054]
【The invention's effect】
According to the first aspect of the present invention, the first threshold value and the second threshold value are set in consideration of a signal component in a band other than the band of the desired channel included in the received signal, that is, in particular in consideration of the influence of the signal component of the adjacent channel. The corrected first correction threshold and the second correction threshold are obtained, and the relationship between the first correction threshold and the second correction threshold and a predetermined quality value corresponding to the reception quality related to a predetermined channel through which a signal always arrives during communication. It is decided to determine whether it is in a synchronized state and whether it is out of synchronization based on the network, so whether it is in a synchronized state and is out of synchronization based on an appropriate threshold according to the actual communication situation As a result, the influence of the signal component of the adjacent channel band can be suppressed to be small, and it is possible to determine synchronization establishment or loss of synchronization more accurately.
[0055]
According to the second aspect of the present invention, since the presence / absence of an adjacent channel is determined from the relationship between the ratio of the input / output power values of the filter means and the characteristics of the filter means, the received signal before demodulation processing is determined. The presence / absence of an adjacent channel can be determined from the state, and as a result, it is possible to check whether an adjacent channel band signal exists in a short time.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of a mobile radio communication terminal according to an embodiment of the present invention.
FIG. 2 is a flowchart of processing executed by a control unit 8;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Antenna 2 ... Analog front end 3 ... Converter 4 ... Roll-off filter 5 ... Searcher
6-1, 6-2, 6-n, despreader 7, symbol synthesizer 8, control unit 8a, threshold calculation unit 8b, synchronization determination unit 8c, adjacent channel detection unit

Claims (4)

It is determined based on a first determination condition that one of the conditions is that a reception quality value related to a first channel through which a signal always arrives during communication is better than a first threshold, and Wireless communication comprising synchronization determination means for determining that the state is out of synchronization based on a second determination condition where one of the conditions is that the reception quality value is worse than a second threshold different from the first threshold In the device
Receiving means for receiving a radio signal;
Filter means for suppressing signal components in a band other than the band of the second channel different from the first channel in the wireless signal received by the receiving means;
Calculating means for calculating a value indicating a ratio of the magnitude of the signal component of the channel band adjacent to the second channel in the radio signal based on the respective power values of the input signal and the output signal of the filter means; ,
The first standard threshold value and the second standard threshold value are corrected by reducing the first standard threshold value and the second standard threshold value so as to decrease as the value calculated by the calculating unit decreases. A wireless communication apparatus comprising correction means for obtaining a threshold value.   The wireless communication apparatus according to claim 1, further comprising: an adjacent channel detection unit that determines whether or not there is an adjacent channel of the second channel based on whether the value calculated by the calculation unit is equal to or greater than a threshold value. .   The calculation means calculates the value as a ratio between a ratio of a power value of an input signal and an output signal of the filter means and a pass rate of the band of the second channel in the filter means. The wireless communication apparatus according to claim 1, wherein:   The calculation means includes a ratio of power values of an input signal and an output signal of the filter means, and an input signal of the filter means when a received signal having no signal component of an adjacent channel band is input to the filter means. The wireless communication apparatus according to claim 1, wherein the value is calculated as a ratio between a ratio of a power value to an output signal.

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