JP4709670B2 - Method for generating spread modulation signal - Google Patents

Description

  The present invention relates to a spread modulation signal generation method in a radio base station, and more particularly to realizing a spread modulation signal generation method that secures processing time and reduces processing load.

  There is “HSDPA (High Speed Downlink Packet Access)” as a high-speed data communication system in “W-CDMA (Wideband-Code Division Multiple Access)” which is a third generation mobile phone system (Non-patent Document 1). The HSDPA wireless base station uses HS-SCCH (High Speed Shared Control CHannel), which is a control data transfer channel signal, and HS-DSCH (High Speed Dedicated Shared CHannel), which is a data transfer channel signal. Communicate with wireless terminal stations.

  In the HSDPA wireless base station, the HS-DSCH modulation method or the like is changed according to the wireless environment or the like, and the HS-SCCH notifies the wireless terminal station of data such as the HS-DSCH modulation method. Hereinafter, the HS-SCCH and HS-DSCH transmitted by the HSDPA wireless base station will be described with reference to FIG.

  In FIG. 5, HS-SCCH corresponds to the slot to be communicated in the HS-SCCH spreading code string (“Code 1” in FIG. 5) for data related to the control of the HS-DSCH modulation method and the like described above. It is generated by spreading modulation with a (partial) code (eg "Code 1-1"). Such spread modulation is performed for each slot, and HS-SCCH having a continuous slot structure is generated. The HS-SCCH is transmitted from the HSDPA radio base station with 3 slots (for example, “Code 1-1” to “Code 1-3”) as one unit (“Code 1” is also repeatedly spread for the next 12 slots. Used for processing).

  The HS-DSCH is a code (for example, “Code2”) corresponding to a slot to be communicated in the HS-DSCH spreading code sequence (“Code2” in FIG. 5). -1 "). Such spread modulation is performed for each slot, and an HS-DSCH having a continuous slot structure is generated. Similarly, this HS-DSCH is transmitted from the HSDPA radio base station with 3 slots (for example, “Code 2-1” to “Code 2-3”) as one unit. Also, HS-DSCH is transmitted with a delay of 2 slots relative to HS-SCCH (“Code 2” is also used for repeated spreading processing for the next 12 slots).

  As described above, the HS-SCCH and the HS-DSCH are spread and modulated with a different spread code for each slot. For this reason, all of the above-described HS-SCCH spreading code sequence and HS-DSCH spreading code sequence are stored in an internal memory (relatively high access speed) in the DSP. It is not preferable to store the data because the memory capacity is increased. On the other hand, each spreading code string is stored in an external memory outside the DSP (access speed is low) and is directly accessed every time spreading modulation increases the time for spreading processing due to the influence of the bus speed or the like. End up. For the problem related to the effective utilization of the memory capacity and the processing time, there is a pipeline processing using DMA (Direct Memory Access) transfer.

  Also, as shown in FIG. 5, the HSDPA radio base station determines the response content from the radio terminal station every three slots, and turns off the HS-SCCH transmission according to the response content (also HS- Accordingly, the DSCH is turned off two slots after the HS-SCCH is turned off.

Harri Holma et al. (Author) "HSDPA / HSUPA FOR UMTS: High Speed Radio Access for Mobile Communications" WILEY

  As described above, in the HSDPA radio base station, HS-SCCH and HS-DSCH are generated by pipeline processing using DMA transfer, and the response content from the radio terminal station is determined every three slots. The HS-SCCH transmission on / off changes according to the response content (Note that the application content is determined as follows: (1) When there is a response from the wireless terminal station, the HSDPA wireless base station sends When there is data to be transmitted (2) When the response from the radio base station is a retransmission request (3) When there is no response from the radio base station, the HS-SCCH is set to transmit on Become).

  For this reason, if pipeline processing using DMA transfer as described above is performed, it is impossible to determine which spreading code should be DMA transferred until the response content from the wireless terminal station is determined. Further, when the spreading code is transferred after determining the response content from the wireless terminal station, the processing time from the determination to the start of transmission is shortened, and the processing load of a processing circuit such as a DSP that performs spread modulation increases. For this reason, a spread modulation signal generation method for generating HS-SCCH and HS-DSCH in which processing load of a processing circuit such as a DSP that performs spread modulation while ensuring processing time from determination to transmission start is reduced is realized. It is desirable.

  According to the present invention, a part corresponding to a slot to be communicated in the first spread code string stored in an external memory mounted outside the arithmetic processing circuit and having a low access speed is mounted inside the arithmetic processing circuit and accessed. First generation for transferring and storing in a high-speed internal memory and generating a first spread modulation signal for one slot that is spread-modulated by a part of the first spread code string stored in the internal memory A step corresponding to a slot to be communicated of the second spreading code sequence, which is executed in parallel with the generation of the first spread modulation signal and stored in the external memory, is transferred to and stored in the internal memory, A second generation step of generating a second spread modulation signal for one slot that is spread-modulated by a part of the second spread code sequence stored in the internal memory, and the first and second Living A method of generating a spread modulation signal in a radio base station that repeats the process at least once, determines the response content from the radio terminal station at a predetermined timing, and performs only the second generation process when a predetermined condition is met A portion corresponding to a slot to be communicated of the first and second spreading code strings that are mounted outside the arithmetic processing circuit and stored in an external memory having a low access speed prior to the predetermined timing. A preliminary code transfer step for transferring the data to the internal memory in advance, a determination step executed in parallel with the preliminary code transfer step for determining a response content from the wireless terminal station, and a response content from the wireless terminal station Is applied to a part of the first and second spreading code sequences stored in advance in the internal memory, the first and second spreading modulations are performed. When the response content from the wireless terminal station does not satisfy the predetermined condition, only the second spread modulation signal spread-modulated by a part of the second spread code sequence stored in advance in the internal memory is generated. And a selective generation step.

  According to the present invention, a method for generating a spread modulation signal for generating HS-SCCH and HS-DSCH in which processing load of a processing circuit such as a DSP that performs spread modulation while ensuring processing time from determination to transmission start is reduced Can be realized.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a radio base station that implements a spread modulation method according to an embodiment of the present invention. It is assumed that the radio base station of this embodiment is an HSDPA radio base station.

  The radio base station 100 shown in FIG. 1 includes a transmission processing circuit 10 that transmits HS-SCCH and HS-DSCH to the radio terminal station 200, a reception processing circuit 20 that receives a response signal from the radio terminal station 200, and a transmission process. And a control processor 30 that controls the circuit 10 and the reception processing circuit 20.

  The transmission processing circuit 10 generates a demodulation result determination unit 11 that determines a response content from the wireless terminal station 200 based on a demodulation result output from the reception processing circuit 20 described later, and generates HS-SCCH and HS-DSCH by spread modulation. A spread modulation unit 13 and a transmission unit 15 that transmits the generated HS-SCCH and HS-DSCH are provided. As described above, the transmission processing circuit 10 generates HS-SCCH and HS-DSCH by pipeline processing using DMA transfer. Further, the transmission processing circuit 10 generates a selective signal as described later in the spread modulation unit 13 in response to the determination of the response content from the wireless terminal station 200. Details of the spread modulation unit 13 will be described later in detail.

  The reception processing circuit 20 includes a demodulation processing unit 21 that performs demodulation processing of an input signal in order to determine the response content from the wireless terminal station 200 at a predetermined timing (for example, once every three slots), and transmission processing of the demodulation result And a demodulation result notifying unit 23 for notifying the circuit 10.

  In addition, as shown in FIG. 2, the spread modulation unit 13 spreads the original data stored in the external memory 13-2 and the data generation unit 1 that generates the original data of the HS-SCCH and the HS-DSCH. Spreading modulation (for example, exclusive modulation) by the internal memory 3 in which a part of the spreading code sequence for DMA transfer is DMA-transferred, the original data generated by the data generator 1 and a part of the spreading code sequence stored in the internal memory 3 An arithmetic circuit 5 that performs a logical operation and a buffer unit 7 that stores the spread modulation signal generated thereby until it is transmitted.

  Hereinafter, the operation will be described with reference to the timing charts of FIGS. First, generation of the spread processing signal of slot 1 will be described. The control processor 30 sends a control signal to the transmission processing circuit 10 so as to generate the HS-SCCH. The spread modulation unit 13 (of the transmission processing circuit 10) generates control data such as the HS-DSCH modulation scheme by the data generation unit 1. Next, the transmission processing circuit 10 performs, by DMA transfer, a portion (Code 1-1) corresponding to slot 1 to be communicated of the HS-SCCH spreading code sequence (Code 1) stored in the external memory 13-2. Store in the internal memory 3. Then, the spread modulation unit 13 spread-modulates the control data with a part of the HS-SCCH spread code sequence (Code 1-1) to generate one slot of HS-SCCH. Such processing is repeated (same for slot 2). The HS-SCCH generated in this way is transmitted in slot 1 (and 2).

  Next, the spread modulation unit 13 generates HS-SCCH and HS-DSCH, which are spread processing signals for slot 3. First, as described above, the data generator 1 generates control data that is data such as the HS-DSCH modulation scheme. Next, a part (Code 1-3) of the HS-SCCH spread code sequence stored in the external memory 13-2 of the spread modulation unit 13 is transferred to the internal memory 3 of the spread modulation unit 13 by DMA transfer. Then, the arithmetic circuit 5 performs spread modulation using the control data and a part (Code1-3) of the HS-SCCH spreading code sequence stored in the internal memory to generate one slot of HS-SCCH.

  Also, the spread modulation unit 13 performs DMA transfer of a part of the HS-DSCH spread code sequence (Code 2-1) stored in the external memory 13-2 of the spread modulation unit 13 in parallel with such spread modulation processing. Thus, the data is transferred to and stored in the internal memory 3 of the spread modulation unit 13. The data generator 1 also generates HS-DSCH original data such as video and audio. Then, the arithmetic circuit 5 performs spread modulation on the HS-DSCH original data using a part of the HS-DSCH spreading code sequence (Code 2-1) stored in the internal memory 3 to generate one slot of HS-DSCH. . The HS-SCCH and HS-DSCH generated in this way are transmitted in slot 3.

  Next, the radio base station 100 determines the response content from the radio terminal station 200 in the slot 3, and generates the HS-SCCH and the HS-DSCH based on the determination result. This will be described with reference to the timing chart of FIG. 3 and the flowchart of FIG. First, the demodulation processing unit 21 of the reception processing circuit 20 demodulates an input signal. Then, the demodulation result notifying unit 23 outputs the demodulation result to the transmission processing circuit 10 (S101-1).

  The transmission processing circuit 10 determines the HS-SCCH and HS-DSCH spreading codes stored in the external memory 13-2 prior to determining the response content of the wireless terminal station 200 based on the demodulation result thus input. A part (Code1-4 and Code2-2) corresponding to the slot to be communicated is DMA-transferred to the internal memory 3 in advance (S101-2).

  Then, the demodulation result determination unit 11 determines the response content from the radio terminal station 200 based on the input demodulation result, and outputs the determination result to the spread modulation unit 13 (S102). The spread modulation unit 13 selectively generates HS-SCCH and HS-DSCCH based on the determination result input from the demodulation result determination unit 11.

  That is, when the determination result satisfies any of the conditions (1) to (3) described above, the spread modulation unit 13 spreads the HS-SCCH and HS-DSCH stored in the internal memory 3 in advance. HS-SCCH and HS-DSCH corresponding to slot 3 are generated by using a part of the code string (Code1-4 and Code2-2) (S103-1 and S104-1). Then, the generated HS-SCCH and HS-DSCH are transmitted (S105).

  Then, when the determination result does not correspond to any of the above conditions (1) to (3), the spread modulation unit 13 stores the HS-DSCH spread code sequence stored in advance in the internal memory 3. An HS-DSCH corresponding to slot 3 is generated using a portion (Code 2-2) (S103-2). Then, the generated HS-DSCH is transmitted (S104-2).

  Thus, prior to the timing of determining the response content from the radio terminal station 200, the HS-SCCH and HS-DSCH spreading codes are DMA-transferred to the internal memory 3 in advance, and the response content from the radio terminal station 200 is determined. By selectively generating the HS-SCCH and the HS-DSCH based on the processing time, the processing time is reduced by the time waiting for the determination result, and the calculation load on the transmission processing circuit 10 can be reduced.

  Further, when the determination result does not correspond to any of the above-mentioned conditions (1) to (3), a part of the HS-DSCH spreading code sequence (Code 2-2) is stored in the internal memory 3. Therefore, the HS-DSCH can be generated immediately after the determination, and there is a margin in processing time. With such a time allowance, the computer resources of the DSP forming the transmission processing circuit 10 can be allocated to other processes (for example, error correction coding and interleaving), and the computer resources can be used more effectively.

It is a figure which shows the radio | wireless base station which implements the production | generation method of the spread modulation signal which concerns on embodiment of this invention. It is a figure which shows the spreading | diffusion modulation part which concerns on embodiment of this invention. It is a figure which shows the process timing of the production | generation method of the spread modulation signal which concerns on embodiment of this invention. It is a figure which shows the processing flow of the production | generation method of the spread modulation signal which concerns on embodiment of this invention. It is a figure explaining HS-SCCH and HS-DSCH which the radio base station of a HSDPA system transmits.

Explanation of symbols

  10 transmission processing circuit, 20 reception processing circuit, 30 control processor, 100 radio base station, 200 radio terminal station

Claims (1)

A portion corresponding to the slot to be communicated in the first spreading code string stored in the external memory having a low access speed mounted outside the arithmetic processing circuit is mounted inside the arithmetic processing circuit and has a high access speed. A first generation step of generating a first spread modulation signal for one slot, which is transferred to and stored in an internal memory and spread-modulated by a part of the first spread code sequence stored in the internal memory;
A part of the second spreading code string that is executed in parallel with the generation of the first spread modulation signal and stored in the external memory is transferred to and stored in an internal memory, and the internal memory A second generation step of generating a second spread modulated signal for one slot that is spread modulated by a portion of the second spread code sequence stored in
Including
A wireless base that repeats the first and second generation steps at least once, determines the response content from the wireless terminal station at a predetermined timing, and performs only the second generation step when a predetermined condition is met A method for generating a spread modulation signal in a station, comprising:
Prior to the predetermined timing, a portion corresponding to a slot to be communicated of the first and second spread code strings stored in the external memory mounted outside the arithmetic processing circuit and having a low access speed is previously stored in the internal memory. A preliminary code transfer process for transferring and storing
A determination step that is executed in parallel with the preliminary code transfer step to determine the response content from the wireless terminal station;
When the response content from the wireless terminal station satisfies a predetermined condition, first and second spread modulation signals that are spread-modulated by a part of the first and second spread code sequences stored in advance in the internal memory are generated. When the response content from the wireless terminal station does not satisfy the predetermined condition, the second spread modulation signal that is spread-modulated only by a part of the second spread code sequence stored in advance in the internal memory is selectively generated. Generation process;
A method for generating a spread modulation signal in a radio base station.

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