Background technology
Fast development along with mobile communication, in the 2G and the 3G communications field, the application of multicarrier system is comparatively extensive, be compared to single-carrier system, multicarrier system is owing to there are a plurality of carrier signals to superpose on time domain, has higher PAPR (peak-to-average power ratio, Peak to Average Power Ratio abbreviates peak-to-average force ratio or PAPR as).And for the system of 3G standard, comprise WCDMA, the system of CDMA2000 and three kinds of standards of TD-SCDMA, the PAPR of single-carrier signal itself is just than higher, if multicarrier system, PAPR will be higher, therefore, in the 3G system, for the signal of undistorted these PAPR of transmission, linearity to some parts requires very high, PA (PA:Power Amplifier, power amplifier) for example is if the excursion of signal exceeds the range of linearity of device, will produce tangible inband distortion and out-of-band radiation, thereby cause the rising of the error rate, reduce systematic function, the size of PAPR has direct influence to the multicarrier system performance.Therefore, effectively reduce the PAPR of system, just seem very necessary, this is directly connected to the performance and the cost of whole system.
Thus, for demand to the PAPR that reduces system, one of technology of following the 3G system applies is exactly peak clipping CFR (Crest Factor Reduction, crest factor a reduce) technology, this be because, if signal not being carried out CFR handles, can't avoid the non-linear and efficiency of PA, for the performance that promotes the 3G system and the efficient of PA, must be by in conjunction with the CFR technology, to reduce the peak-to-average power ratio of signal, the non-linear mis-behave that causes and the efficient that reduce owing to PA reduce problem.
In present application, use more CFR technology and mainly contain two kinds: Peak Window CrestFactor Reduction (is called for short: PW-CFR) (be called for short: PC-CFR) with Peak Cancellation Crest Factor Reduction.For the PW-CFR technology, it need not to obtain corresponding carrier frequency point information, and because the inner filter order that uses of CFR is low, the time delay of introducing is also fewer, and the occasion lower for ask for something has certain application value, but since its peak clipping performance a little less than, reduction PAPR that can only be less, and cause out of band spectrum to be revealed easily, therefore, less use in present application.
And, because its peak clipping better performances, be applicable to all standards for the PC-CFR technology, and comprise 2G and 3G, single carrier and multicarrier are suitable for too, therefore, in present practical application, use more extensively, be one of technology of 3G VS .NET Prerequisites.But the PC-CFR technology also has some to use drawback, it need know the frequency point information of corresponding carrier wave accurately, so that the form of the filter coefficient combination of being adopted among definite PC-CFR, otherwise, if it is improper that the filter coefficient combination is adopted, to produce the channel that does not have carrier wave and disturb, reduce systematic function.
In the applied in any combination of BBU-RRU, CFR is used for the RRU end, and because BBU is the device that produces signal, can know the carrier frequency point information of the signal that self produced exactly, thereby can the carrier frequency point message transmission be arrived RRU by the host-host protocol between BBU and the RRU, the RRU end obtains corresponding carrier frequency point information, and the needed filter coefficient combination of CFR can be set accurately, realizes correct CFR function.And for the occasion beyond the BBU-RRU, for example: digital RF far-drawing system, digital direct discharging station or digital radio repeater, because the relay of digital high-frequency amplification station or digital radio repeater generally can't obtain corresponding carrier frequency point information, cause can't be correct the combination of the needed filter coefficient of CFR is set, thereby also cause greatly reducing the performance of CFR, directly influence the overall performance of system.
Embodiment
Below in the mode of specific embodiment the solution of the present invention is described in detail.
As shown in Figure 1, be the schematic flow sheet of the CFR processing method with automatic carrier track function of invention, it comprises step:
Step S101: according to the definite carrier wave of using of the energy of carrier wave, obtain the frequency point information of the carrier wave of using, enter step S102;
Step S102: according to the frequency point information of the described carrier wave of using, the filter coefficient combination of the required application of CFR is set, carries out CFR and handle.
In view of the above, it is to determine the current carrier wave that is using according to the signal energy of each carrier wave, after having determined the current carrier wave that is using, can obtain the frequency point information of this carrier wave that is using, thereby can set out the filter coefficient combination of the required application of CFR exactly according to this frequency point information, carry out CFR and handle, guarantee the normal use of CFR function, promoted systematic function.
Wherein, after the frequency point information of the carrier wave that has obtained using, the process of the filter system combination of the required application of CFR is set according to the frequency point information of the carrier wave of using, can be to realize with existing mode, for example, will not add to give unnecessary details to this process at this in preceding described PC-CFR technology.
And wherein determine the carrier wave of using, the process of obtaining the frequency point information of the carrier wave of using different implementation methods to be arranged according to the energy of carrier wave, different implementation methods goes for different communication standards:
Wherein a kind of implementation, be by agreement is carried out dissection process, obtain the SCH channel information of using, then according to the energy size of each SCH channel, the carrier channel that energy value maximum and energy value are defined as using greater than the SCH channel of predetermined threshold value, and can learn the carrier wave that is using in view of the above.This implementation goes for standards such as GSM, DCS, CDMA.Specifically, be example with the GSM standard, by the SCH channel information that gsm protocol is carried out dissection process, obtain using, and obtain the channel energy of each channel, sort according to the size of energy value, preferentially select the big channel of energy; If the energy of two adjacent channels is all bigger, then stay that big channel of energy, reject that less relatively channel of energy; When the predetermined threshold value of channel energy, directly reject this channel, thereby retain useful channel less than setting; Thereby finally determine the channel that remains, be the channel of energy value greater than predetermined threshold value and energy value maximum, and the carrier channel that this channel is defined as using, and learn the carrier wave that is using in view of the above, realize accurate identification to the carrier wave that is using.After having determined the carrier wave that is using, just can further determine corresponding carrier frequency point information, determine that according to carrier wave the process of the frequency point information of carrier wave can adopt existing mode in the prior art, do not repeat them here.
This implementation preferably is applied to digital radio repeater system, can have application promise in clinical practice at digital radio repeater system.This be because, in digital radio repeater system, there is extraneous wireless signal, the interference that is subjected to is more, signal strength signal intensity is also suddenly big or suddenly small, to having relatively high expectations of automatic carrier track, and by the dissection process to agreement, can have better anti-disturbance performance, can guarantee to capture exactly corresponding carrier frequency point information.
And another determines the carrier wave of using, the implementation of obtaining the frequency point information of the carrier wave of using according to the energy of carrier wave, then be to handle by the digital signal after the A/D conversion being carried out Digital Down Convert, obtain corresponding baseband signal, add up the signal energy of each baseband signal, with signal energy greater than predetermined threshold value and the carrier wave that is defined as using greater than the corresponding carrier wave of the baseband signal of default disparity threshold with the difference of the signal energy of adjacent any one carrier wave.This implementation is equally applicable to communication standards such as GSM, DCS, CDMA, also is applicable to WCDMA, CDMA2000, Wimax and TD-SCDMA communication standard simultaneously.Specifically, be based on the mode decision scheme of energy statistics, to the digital signal after the A/D conversion, carrying out Digital Down Convert handles, also promptly carry out mixing, extract and Filtering Processing, obtain corresponding baseband signal, the energy of statistics baseband signal, the size of the energy of while two carrier waves that also statistics is adjacent with this baseband signal left and right sides, as long as satisfy following three conditions simultaneously, can judge that then this baseband signal is effective carrier wave, be the current carrier wave that is using: the signal energy of current carrier wave is greater than the predetermined threshold value of setting, the signal energy of this carrier wave is bigger than the signal energy of two carrier waves about being adjacent, and the difference of the signal energy of two carrier waves that the current carrier wave and the left and right sides are adjacent is greater than default disparity threshold, thereby realizes the accurate identification to the carrier wave that is using.After having determined the carrier wave that is using, just can further determine corresponding carrier frequency point information, determine that according to carrier wave the process of the frequency point information of carrier wave can adopt existing mode in the prior art, do not repeat them here.
This implementation, preferably be applicable to digital optical fiber direct station and digital RF far-drawing system, this be because, directly the be coupled downstream signal of base station of relay in digital optical fiber direct station or the digital RF far-drawing system, this signal stabilization and power are bigger, are suitable for carrying out the automatic carrier track processing of this mode.
According to the CFR processing method of the automatic carrier track function of having of the invention described above, the present invention also provides a kind of CFR processing unit with automatic carrier track function.
As shown in Figure 2, be the structural representation with CFR processing unit embodiment of automatic carrier track function of the present invention, it comprises:
Automatically carrier track subsystem 201 is used for obtaining the frequency point information of the carrier wave of using according to the definite carrier wave of using of the energy of carrier wave, and the frequency point information of this carrier wave of using is exported to CFR subsystem 202;
CFR subsystem 202 is used for the frequency point information according to the described carrier wave of using, and the filter coefficient combination of the required application of CFR is set, and carries out CFR and handles.
In view of the above, it is to determine the current carrier wave that is using by automatic carrier track subsystem 201 according to the signal energy of each carrier wave, after having determined the current carrier wave that is using, can obtain the frequency point information of this carrier wave that is using, and the frequency point information of this carrier wave that is using sent to CFR subsystem 202, thereby CFR subsystem 202 can set out the filter coefficient combination of the required application of CFR exactly according to this frequency point information, carrying out CFR handles, guarantee the normal use of CFR function, promoted systematic function.
Wherein, after the frequency point information of the carrier wave that has obtained using, the CFR subsystem is provided with the process of the filter system combination of the required application of CFR according to the frequency point information of the carrier wave of using, can be to realize with existing mode, for example, will not add to give unnecessary details to this process at this in preceding described PC-CFR technology.
And wherein determine the carrier wave of using, the process of obtaining the frequency point information of the carrier wave of using different implementation methods to be arranged according to the energy of automatic carrier track subsystem 201 carrier waves, different implementation methods goes for different communication standards:
Wherein a kind of implementation, be by agreement is carried out dissection process, obtain the SCH channel information of using, then according to the energy size of each SCH channel, the carrier channel that energy value maximum and energy value are defined as using greater than the SCH channel of predetermined threshold value.This implementation goes for communication standards such as GSM, DCS, CDMA.Specifically, be example with the GSM standard, by the SCH channel information that gsm protocol is carried out dissection process, obtain using, and obtain the channel energy of each channel, sort according to the size of energy value, preferentially select the big channel of energy; If the energy of two adjacent channels is all bigger, then stay that big channel of energy, reject that less relatively channel of energy; When the predetermined threshold value of channel energy, directly reject this channel, thereby retain useful channel less than setting; Thereby finally determine the channel that remains, be the channel of energy value greater than predetermined threshold value and energy value maximum, and with this channel as the carrier channel of using, realize accurate identification, and learn the carrier wave that is using in view of the above the carrier channel of using.After having determined the carrier wave that is using, just can further determine corresponding carrier frequency point information, this process can adopt existing mode in the prior art, does not repeat them here.
As shown in Figure 3, be that in the case, this automatic carrier track subsystem includes at the structural representation with CFR processing unit of automatic carrier track function of the present invention that adopts under this mode:
Protocol analysis unit 20111 is used for agreement is carried out dissection process, obtains the SCH channel information of using;
Energy statistics comparing unit 20112 is used to add up and the energy size of protocol analysis unit 20111 each the SCH channel that obtains of resolving relatively, determines energy value maximum and the energy value SCH channel greater than predetermined threshold value;
Carrier wave determining unit 20113 is used for the carrier wave that energy value maximum that energy statistics comparing unit 20112 is relatively drawn and energy value are defined as using greater than the carrier wave of the SCH channel correspondence of predetermined threshold value;
Frequency point information unit 20114, the frequency point information of the current carrier wave that is using that is used for determining that carrier wave determining unit 20113 is determined.
This implementation preferably is applied to digital radio repeater system, can have application promise in clinical practice at digital radio repeater system.This be because, in digital radio repeater system, the interference that extraneous wireless signal is subjected to is more, signal strength signal intensity is also suddenly big or suddenly small, to having relatively high expectations of automatic carrier track, and, can have better anti-disturbance performance by dissection process to agreement, can guarantee to capture exactly corresponding carrier frequency point information.
Referring to shown in Figure 4, be the schematic diagram when the CFR processing unit with automatic carrier track function of the present invention is applied to digital radio repeater system.Because handling, CFR is mainly used in down link, and generally do not need to be applied in the up link, therefore, for traditional digital radio repeater system, embedded CFR processing unit with automatic carrier track function of the present invention in its digital intermediate frequency subsystem, in other words the CFR treatment technology with automatic carrier track function of the present invention is embedded in the digital intermediate frequency subsystem, promptly can guarantee to trace into exactly the current carrier wave of using, and obtain corresponding carrier frequency point information, guarantee to use accurately the CFR technology.
And another determines the carrier wave of using, the implementation of obtaining the frequency point information of the carrier wave of using according to the energy of carrier wave, then be to handle by the digital signal after the A/D conversion being carried out Digital Down Convert, obtain corresponding baseband signal, add up the signal energy of each baseband signal, the carrier wave that signal energy is defined as using greater than the corresponding carrier wave of the baseband signal of default disparity threshold greater than predetermined threshold value, with the difference of the signal energy of adjacent any one carrier wave.This implementation is equally applicable to GSM, DCS, cdma communication standard, also goes for WCDMA, CDMA2000, Wimax and TD-SCDMA communication standard simultaneously.Specifically, be based on the mode decision scheme of energy statistics, to the digital signal after the A/D conversion, carrying out Digital Down Convert handles, also promptly carry out mixing, extract and Filtering Processing, obtain corresponding baseband signal, the energy of statistics baseband signal, the size of the energy of while two carrier waves that also statistics is adjacent with this baseband signal left and right sides, as long as satisfy following three conditions simultaneously, can judge that then this baseband signal is effective carrier wave, be the current carrier wave that is using: the signal energy of current carrier wave is greater than the predetermined threshold value of setting, the signal energy of this carrier wave is bigger than the signal energy of two carrier waves about being adjacent, and the difference of the signal energy of two carrier waves that the current carrier wave and the left and right sides are adjacent is greater than default disparity threshold, thereby realizes the accurate identification to the carrier wave that is using.After having determined the carrier wave that is using, just can further determine corresponding carrier frequency point information, this process can adopt existing mode in the prior art, does not repeat them here.
As shown in Figure 5, be that in the case, this automatic carrier track subsystem includes at the structural representation with CFR processing unit of automatic carrier track function of the present invention that adopts under this mode:
Digital Down Convert unit 20121 is used for that the digital signal after the A/D conversion is carried out Digital Down Convert and handles, and obtains corresponding baseband signal;
Energy statistics comparing unit 20122, be used to add up and the baseband signal that obtains of comparative figures down-converter unit 20121 and the energy size of adjacent carrier thereof, determine signal energy greater than predetermined threshold value, with the difference of the signal energy of adjacent any one carrier wave carrier wave greater than default disparity threshold;
Carrier wave determining unit 20123 is used for the carrier wave that signal energy that energy statistics comparing unit 20122 is relatively drawn is defined as using greater than the carrier wave of default disparity threshold greater than predetermined threshold value, with the difference of the signal energy of adjacent any one carrier wave;
Frequency point information unit 20124, the frequency point information of the current carrier wave that is using that is used for determining that carrier wave determining unit 20123 is determined.
This implementation, preferably be applicable to digital optical fiber direct station and digital RF far-drawing system, this be because, directly the be coupled downstream signal of base station of the relay of digital optical fiber direct station or digital RF far-drawing system, this signal stabilization and power are bigger, are suitable for carrying out the automatic carrier track processing of this mode.
Referring to shown in Figure 6, be, traditional digital optical fiber repeater system or the down link digital processing flow process principle schematic in the digital RF far-drawing system that it is to use traditional digital processing mode, does not use the CFR technology in the prior art.
Referring to shown in Figure 7, be the down link digital processing theory structure schematic diagram when being applied to the CFR processing unit with automatic carrier track function of the present invention in digital optical fiber repeater system or the digital RF far-drawing system.As seen from the figure, adopted the CFR processing unit with automatic carrier track function of the present invention at its down link.It should be noted that, in this example, be automatic carrier track subsystem and CFR subsystem branch to be come be provided with, with automatic carrier track subsystem application in the relay of digital optical fiber direct station or digital RF far-drawing system, be arranged between DDC subsystem and the CPRI framing subsystem, and, its input is connected with the output of DUC subsystem with the capped end of CFR subsystem application in digital optical fiber direct station or digital RF far-drawing system.The reason that is provided with like this is in order to make full use of fiber bandwidth, and this is to consider, essentially, signal after transmission DDC handles will take more bandwidth, and the frequency point information of transmission carrier wave, frequency point information has only a spot of amount of information, shared bandwidth is also few, therefore, and this processing mode, be reasonable and effective, and can reduce system cost.In this application mode, automatically the carrier track subsystem is followed the tracks of corresponding carrier frequency point, and carrier frequency point information is transferred to capped end by the CPRI subsystem, capped end is separated frame by CPRI and is handled, recover carrier frequency point information, be transferred to the CFR subsystem, the desired filter coefficient combination of CFR correctly be set, thereby guarantee the correct application of CFR function with assurance.
The CFR processing unit with automatic carrier track function of the invention described above can utilize special-purpose asic chip to realize, also can utilize programmable logic devices such as DSP, FPGA, CPLD, EPLD to realize.When using as a whole, when for example being applied to the digital radio repeater system shown in Fig. 4, can realize with an asic chip, when breaking use, when for example being applied to digital optical fiber direct station shown in Fig. 7 or digital RF far-drawing system, then carrier track subsystem and CFR subsystem are realized with an asic chip respectively automatically.
In addition, the CFR processing method and the device with automatic carrier track function of the invention described above, specifically can be applicable to the systems such as base station, base station sub-system, radio frequency stretch system and carrier dispatching of communication standards such as GSM, CDMA, DCS, JDC, TD-SCDMA, WCDMA, CDMA2000, Wimax, do not repeat them here.
In addition, CFR processing unit according to the automatic carrier track function of having of the invention described above, the present invention also provides a kind of communication system, it includes the CFR processing unit of the automatic carrier track function of having of the invention described above, this CFR processing unit with automatic carrier track function can not repeat them here as mentioned above in the Application in Communication Systems mode.
Above-described embodiment of the present invention only is the detailed description to preferred embodiment of the present invention, does not constitute the qualification to protection range of the present invention.Any modification of being done within the spirit and principles in the present invention, be equal to and replace and improvement etc., all should be included within the claim protection range of the present invention.