Abstract:
Disclosed are a power adjustment method and an apparatus based on low delay power detection before digital pre-distortion. The method comprises the following steps: according to pre-configured system carrier information, obtaining effective carrier information containing an effective carrier channel corresponding to each effective carrier; performing sampling on carrier data of each effective carrier channel according to the obtained effective carrier information, and then calculating combination power Pa of effective carriers before digital up conversion or digital peak clipping cancellation according to the sampling; and using the combination power Pa of the effective carriers to perform power adjustment before digital pre-distortion. The present invention moves power calculation ahead of an up conversion module, fully utilizes inherent delay of digital up conversion and a peak clipping module to offset time required for the power calculation, and effectively reduces system delay.

Description:
This application is a national stage application under 35 U.S.C. §371 from PCT Application No. PCT/CN2013/085188, filed Oct. 14, 2013, which claims the priority benefit of China Application No. 201310034381.0, filed Jan. 29, 2013. 
     TECHNICAL FIELD 
     The disclosure relates to the field of wireless communication technology, and in particular to a method and apparatus for power adjustment based on low-delay power detection before Digital Pre-Distortion (DPD). 
     BACKGROUND 
     A Remote Radio unit is a vital part of an existing wireless communication system, in particular a third or fourth generation mobile communication system. A DPD module is a core part of a Remote Radio unit. An index of the DPD module is directly related to maximal transmit power of the Remote Radio unit, and thus impacts a coverage radius of a cell as well as an access index of a terminal. 
     An existing DPD module is in general based on a structure of a search table. However, before the table is searched, power of data input to the module has to be computed, such that content of an entry can be determined. Such a power detecting module will introduce a large delay as well as substantial computation. The delay will impact a delay index of the Remote Radio unit, increasing system cache for delay. The substantial computation will increase computation cost of the Remote Radio unit. 
     SUMMARY 
     Embodiments herein provide a method and apparatus for power adjustment based on low-delay power detection before DPD, capable of effectively lowering a system delay and reducing computation. 
     To this end, a technical solution according to an embodiment herein may be implemented as follows. 
     According to an embodiment herein, a method for power adjustment based on low-delay power detection before Digital Pre-Distortion (DPD), includes steps of: 
     obtaining, according to preconfigured system carrier information, effective carrier information including an effective carrier channel corresponding to an effective carrier; 
     sampling, according to the obtained effective carrier information, carrier data on an effective carrier channel, and then determining, according to sampled carrier data on effective carrier channels, total power Pa of effective carriers before Digital Up Conversion (DUC) or before digital Crest Factor Reduction (CFR); and 
     before DPD, performing power adjustment using the total power Pa of the effective carriers. 
     The sampling, according to the obtained effective carrier information, carrier data on an effective carrier channel may include: 
     selecting data sample points corresponding to a carrier data rate used; and 
     sampling, at the data sample points, carrier data before DUC on an effective carrier channel. 
     The sampling, according to the obtained effective carrier information, carrier data on an effective carrier channel may include: 
     selecting data sample points according to a carrier data rate and a DUC interpolation multiple; and 
     sampling, at the data sample points, carrier data after DUC on an effective carrier channel. 
     The determining, according to sampled carrier data on effective carrier channels, total power Pa of effective carriers before Digital Up Conversion (DUC) or before digital Crest Factor Reduction (CFR) may include: 
     calculating, using power of sampled carrier data at the data sample points on an effective carrier channel, average carrier power of the effective carrier channel; and 
     obtaining the total power Pa of the effective carriers by summing the average carrier power over the effective carrier channels. 
     The determining, according to sampled carrier data on effective carrier channels, total power Pa of effective carriers before Digital Up Conversion (DUC) or before digital Crest Factor Reduction (CFR) may include: 
     obtaining total power of the effective carriers at a data sample point by summing power of carrier data sampled at the data sample point over the effective carrier channels; and 
     obtaining the total power Pa of the effective carriers by averaging the total power of the effective carriers at the data sample points. 
     The before DPD, performing power adjustment using the total power Pa of the effective carriers may include: 
     searching a power compensating search table made beforehand for a compensating entry Ga corresponding to the total power Pa of the effective carriers; 
     determining, according to the found compensating entry Ga, an adjusted power value; and 
     sending the adjusted power value into a DPD module; performing, by the DPD module, power adjustment according to the adjusted power value, such that power loss due to peak elimination by a CFR module of a Remote Radio unit is compensated. 
     The adjusted power value may be a product of the total power Pa of the effective carriers and the compensating entry Ga. 
     According to an embodiment herein, an apparatus for power adjustment based on low-delay power detection before Digital Pre-Distortion (DPD) includes: 
     a configuring module configured for: obtaining, according to preconfigured system carrier information, effective carrier information including an input data channel corresponding to an effective carrier; 
     a sampling computing module configured for: sampling, according to the obtained effective carrier information, carrier data on an effective carrier channel, and then determining, according to carrier data on effective carrier channels, total power Pa of effective carriers before Digital Up Conversion (DUC) or before digital Crest Factor Reduction (CFR); and 
     an adjusting module configured for: before DPD, performing power adjustment using the total power Pa of the effective carriers. 
     The sampling computing module may include: 
     a sampling module configured for: selecting data sample points corresponding to a carrier data rate used, and sampling, at the data sample points, carrier data before DUC on an effective carrier channel; and 
     a total power computing module configured for: determining, according to the sampled carrier data on the effective carrier channels, the total power Pa of the effective carriers before DUC or before Digital CFR. 
     The sampling computing module may include: 
     a sampling module configured for: selecting data sample points according to a carrier data rate and a DUO interpolation multiple, and sampling, at the data sample points, carrier data after DUO on an effective carrier channel; and 
     a total power computing module configured for: determining, according to the sampled carrier data on the effective carrier channels, the total power Pa of the effective carriers before DUO or before Digital CFR. 
     Compared with an existing solution, a technical solution provided herein has beneficial effects as follows. 
     1, power computation is moved forward, ahead of an Up Conversion module; inherent delays of DUO and CFR modules may be fully exploited to cancel out an amount of time as required by power computation, such that a system delay may be lowered effectively, in theory lowering the delay to L/fb. 
     2, an amount of computation as required by power computation may be greatly lowered, too. The amount of computation as required herein may be M*fb, whereas N*fb will be required with a convention solution. The N may be an Up Conversion interpolation multiple. In general, the N is far greater than the M. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flowchart of a method for power adjustment based on low-delay power detection before DPD according to an embodiment herein. 
         FIG. 2  is a diagram of an apparatus for power adjustment based on low-delay power detection before DPD according to an embodiment herein. 
         FIG. 3  is a block diagram of a structure of a method for low-delay power detection before DPD according to an embodiment herein. 
         FIG. 4  is a block diagram of a structure of a method for low-delay power detection before DPD according to an embodiment herein. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment herein will be elaborated below with reference to the accompanying drawing. Note that an embodiment illustrated below is for illustrating and explaining the disclosure only, and is not intended to limit the disclosure. 
     Embodiments herein are directed at improving a power detecting module in DPD, so as to reduce a delay and amount of computation. 
       FIG. 1  is a flowchart of a method for power adjustment based on low-delay power detection before DPD according to an embodiment herein. As shown in  FIG. 1 , the method includes steps as follows. 
     In step S 101 , effective carrier information including an effective carrier channel corresponding to an effective carrier is obtained according to preconfigured system carrier information. 
     In step S 102 , carrier data on an effective carrier channel is sampled according to the obtained effective carrier information, and then total power Pa of effective carriers before Digital Up Conversion (DUC) or before digital Crest Factor Reduction (CFR) is determined according to sampled carrier data on effective carrier channels. 
     In step S 103 , power adjustment is performed before DPD using the total power Pa of the effective carriers. 
     The carrier data on an effective carrier channel may be sampled according to the obtained effective carrier information by: selecting data sample points corresponding to a carrier data rate used; and sampling, at the data sample points, carrier data before DUC on an effective carrier channel. 
     The carrier data on an effective carrier channel may be sampled according to the obtained effective carrier information by: selecting data sample points according to a carrier data rate and a DUC interpolation multiple; and sampling, at the data sample points, carrier data after DUC on an effective carrier channel. 
     The total power Pa of the effective carriers before DUC or before digital CFR may be determined by: calculating, using power of sampled carrier data at the data sample points on an effective carrier channel, average carrier power of the effective carrier channel; and obtaining the total power Pa of the effective carriers by summing the average carrier power over the effective carrier channels. 
     The total power Pa of the effective carriers before DUC or before digital CFR may be determined by: obtaining total power of the effective carriers at a data sample point by summing power of carrier data sampled at the data sample point over the effective carrier channels; and obtaining the total power Pa of the effective carriers by averaging the total power of the effective carriers at the data sample points. 
     Power adjustment may be performed before DPD using the total power Pa of the effective carriers by: searching a power compensating search table made beforehand for a compensating entry Ga corresponding to the total power Pa of the effective carriers; determining, according to the found compensating entry Ga, an adjusted power value; sending the adjusted power value into a DPD module; performing, by the DPD module, power adjustment according to the adjusted power value, such that power loss due to peak elimination by a CFR module of a Remote Radio unit is compensated. 
     The adjusted power value may be a product of the total power Pa of the effective carriers and the compensating entry Ga. 
       FIG. 2  is a diagram of an apparatus for power adjustment based on low-delay power detection before DPD according to an embodiment herein. As shown in  FIG. 2 , the apparatus includes a configuring module, a sampling computing module, and an adjusting module. The configuring module  201  may be configured for: obtaining, according to preconfigured system carrier information, effective carrier information including an input data channel corresponding to an effective carrier. The sampling computing module  202  may be configured for: sampling, according to the obtained effective carrier information, carrier data on an effective carrier channel, and then determining, according to sampled carrier data on effective carrier channels, total power Pa of effective carriers before Digital Up Conversion (DUC) or before digital Crest Factor Reduction (CFR). The adjusting module  203  may be configured for: before DPD, performing power adjustment using the total power Pa of the effective carriers. 
     The sampling computing module  202  may include: a sampling module configured for: selecting data sample points corresponding to a carrier data rate used, and sampling, at the data sample points, carrier data before DUC on an effective carrier channel; and a total power computing module configured for: determining, according to the sampled carrier data on the effective carrier channels, the total power Pa of the effective carriers before DUC or before Digital CFR. 
     The sampling computing module may include: a sampling module configured for: selecting data sample points according to a carrier data rate and a DUC interpolation multiple, and sampling, at the data sample points, carrier data after DUC on an effective carrier channel; and a total power computing module configured for: determining, according to the sampled carrier data on the effective carrier channels, the total power Pa of the effective carriers before DUO or before Digital CFR. 
     In practical application, the apparatus for power adjustment based on low-delay power detection before DPD may be deployed in a Remote Radio unit in a wireless communication system. Each of the configuring module  201 , the sampling computing module  202 , and the adjusting module  203  may be implemented by a CPU, a Digital Signal Processor (DSP), or a Field Programmable Gate Array (FPGA) of the Remote Radio unit. 
       FIG. 3  is a block diagram of a structure of a method for low-delay power detection before DPD according to an embodiment herein. As shown in  FIG. 3 , the structure may include modules A-C. The module A may be a carrier configuring apparatus providing the effective carrier information. The effective carrier information may include a number of information-bearing effective carriers in the system and input data channels each corresponding to an effective carrier. The effective carrier information may be available through upper layer software configuration. The module B may be an effective carrier data computing apparatus which may calculate average effective carrier power corresponding to the information provided by the apparatus A. The module C may be a gain adjusting apparatus which may compensate a power difference introduced by peak elimination by a next-stage CFR module. 
     The module A may provide effective filtering information specifically through steps as follows. 
     In step A 1 , a maximal number Mmax of carrier channels in the system may be determined. 
     In step A 2 , a channel number ( 0 ,  1 ,  2 , . . . , Mmax−1) corresponding to a carrier channel may be determined. 
     In step A 3 , a number M of system-configured carrier channels may be determined, with M≦Mmax. 
     In step A 4 , a channel number  0 ,  1 ,  2 , . . . , M−1 of a configured effective carrier channel may be determined. 
     The module B may calculate the average effective carrier power corresponding to the information provided by the apparatus A with steps as follows. 
     In step B 1 , an input carrier data rate fb and a computing rate fm of the apparatus may be selected. fm=K*fb, with K=M, such that computing efficiency may be improved effectively while avoiding computation waste. 
     In step B 2 , a data sample length (or data sample points), denoted by L, may be selected. 
     In step B 3 , according to effective carrier information configured in A, (L-points) sampling may be performed respectively and carrier power p 0 , p 1 , p 2 , . . . , pM−1 corresponding to the channel numbers  0 ,  1 ,  2 , . . . , M−1 of the effective carrier channels may be computed. 
     In step B 4 , the total power of all the effective carriers may be computed. 
     The module C may compensate the power difference introduced by peak elimination by the next-stage CFR module through steps as follows. 
     In step C 1 , a power compensating search table may be made according to carrier configuration in A and a maximal total power Pmax allowed by the system. The power compensating search table may be obtained by traversing different carrier power configurations through algorithm simulation. 
     In step C 2 , a compensating entry Ga in C 1  may be found according to a result Pa calculated in B. 
     In step C 3 , an adjusted power value may be obtained as a product of Ga and Pa, and sent into a DPD module. 
     A specific embodiment according to  FIG. 3  will be elaborated below. 
     In step A 1 , a maximal number Mmax of carrier channels in the system may be determined. Mmax=12, for example. 
     In step A 2 , a channel number ( 0 ,  1 ,  2 , . . . ,  11 ) corresponding to a carrier channel may be determined. 
     In step A 3 , a number M of system-configured carrier channels may be determined. M=6, for example. 
     In step A 4 , a channel number  0 ,  1 ,  2 ,  3 ,  4 ,  5  of a configured effective carrier channel may be determined. 
     In step B 1 , a carrier data rate fb=1.28 MHz may be selected. As M=6, a computing rate fm of the apparatus=6*fb=7.68 MHz may be selected. 
     In step B 2 , a data sample length L=128 (under rate fb) may be selected. 
     In step B 3 , according to effective carrier information configured in A, 128-pt sampling may be performed respectively and carrier power p 0 , p 1 , p 2 , . . . , p 5  corresponding to channel numbers  0 ,  1 ,  2 , . . . ,  5  of the effective carrier channels may be computed. 
     In step B 4 , the total power of all the effective carriers may be computed. Assume that Pa=−16 dbfs, for example. Note that steps B 3  and B 4  may also be broken down into summing over 6 carrier data samples at a data sample point (and the rate fm may be fully exploited), and then averaging 128 data sample points. 
     In step C 1 , a power compensating search table may be made according to carrier configuration in A and a maximal total power Pmax allowed by the system. Assume that M=6, Pmax=−15 dbfs, for example. An inter-entry difference may be 0.1 dB, with a total of 150 entries. (With a total power less than −30 dbfs, no CFR is performed, as it is deemed that no adjustment is required.) 
     In step C 2 , a compensating entry Ga=0.9968 in C 1  may be found according to a result Pa=−16 dbfs calculated in B. 
     In step C 3 , an adjusted power value Po=−16.028 dbfs may be obtained as a product of Ga=0.9968 and Pa=−16 dbfs, and sent into a DPD module. 
       FIG. 4  is a block diagram of a structure of a method for low-delay power detection before DPD according to an embodiment herein. As shown in  FIG. 4 , the structure may include steps as follows. 
     In step A 1 , a maximal number Mmax of carrier channels in the system may be determined. Mmax=12, for example. 
     In step A 2 , a channel number ( 0 ,  1 ,  2 , . . . ,  11 ) corresponding to a carrier channel may be determined. 
     In step A 3 , a number M of system-configured carrier channels may be determined. M=12, for example. 
     In step A 4 , a channel number  0 ,  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10 ,  11  of a configured effective carrier channel may be determined. 
     In step B 1 , a carrier data rate fb=1.28 MHz may be selected. As M=6, a computing rate fm of the apparatus=6*fb=7.68 MHz may be selected. 
     In step B 2 , a data sample length L=8192 may be selected. (Under Up Conversion of a multiple N=64, the original baseband 128 pts become 8192 pts after interpolation.) 
     In step B 3 , according to effective carrier information configured in A, 128-pt sampling may be performed respectively and carrier power p 0 , p 1 , p 2 , . . . , p 5  corresponding to channel numbers  0 ,  1 ,  2 , . . . ,  5  of the effective carrier channels may be computed. 
     In step B 4 , the total power Pa of the effective carriers at the L points may be computed. Pa=−15 dbfs, for example. 
     In step C 1 , a power compensating search table may be made according to carrier configuration in A and a maximal total power Pmax allowed by the system. Assume that M=12, Pmax=−15 dbfs, for example. An inter-entry difference may be 0.1 dB, with a total of 150 entries. (With a total power less than −30 dbfs, no CFR is performed, as it is deemed that no adjustment is required.) 
     In step C 2 , a compensating entry Ga=0.995 in C 1  may be found according to a result Pa=−15 dbfs calculated in B. 
     In step C 3 , an adjusted power value Po=−15.022 dbfs may be obtained as a product of Ga=0.995 and Pa=−15 dbfs, and sent into a DPD module. 
     To sum up, a technical solution provided herein has technical effects as follows. 
     1, power computation is moved forward, ahead of an Up Conversion module; inherent delays of DUC and CFR modules may be fully exploited to cancel out an amount of time as required by power computation, such that a system delay may be lowered effectively, in theory lowering the delay to L/fb. 
     2, an amount of computation as required by power computation may be greatly lowered, too. The amount of computation as required herein may be M*fb, whereas N*fb will be required with a convention solution. The N may be an Up Conversion interpolation multiple. In general, the N is far greater than the M. 
     Although elaborated as above, the disclosure is not limited thereto. Those skilled in the art may make various modifications according to the principle herein. Therefore, any modification, equivalent replacement, improvement, and the like made according to the principle of the present disclosure should be included in the scope of the present disclosure. 
     INDUSTRIAL APPLICABILITY 
     According to an embodiment herein, effective carrier information including an effective carrier channel corresponding to an effective carrier is obtained according to preconfigured system carrier information; carrier data on an effective carrier channel is sampled according to the obtained effective carrier information, and then total power Pa of effective carriers before Digital Up Conversion (DUC) or before digital Crest Factor Reduction (CFR) is determined according to sampled carrier data on effective carrier channels; power adjustment is performed before DPD using the total power Pa of the effective carriers. In this way, power computation is moved forward, ahead of an Up Conversion module; inherent delays of DUC and CFR modules may be fully exploited to cancel out an amount of time as required by power computation, effectively lowering a system delay.