CN100454799C - A power control method for code division multiple access communication system - Google Patents

Abstract

The present invention provides a power controlling method for a CDMA (code division multiple access) communication system, which is used for achieving the purpose of burst data service/power control. Signal-to-noise ratios of public information in a period of private data information transmission of a user are measured and compared to form public information transmission power control command values (TPC command values) which are accumulated to form TPC command accumulated values. A control base station transmits information frame time transmission power which carries user private data information and needs to be transmitted to realize the fading and the path loss of an approximately continuous tracking channel. The present invention can not only maintain communication with high quality, but also generate no interference in other users, and overcomes the limitations which are generated when a down closed loop power controlling method existing in the prior art is applied to burst data service.

Description

A power control method for code division multiple access communication system

technical field

The invention relates to a power control method of a wireless communication system, in particular to a power control method on the downlink of a code division multiple access communication system.

Background technique

Code Division Multiple Access (CDMA) communication system is a self-interference system, all mobile users occupy the same bandwidth and frequency, different users code division multiplexing at the same time, the interference between codes is very serious, channel fading and multipath interference have a great impact on The restriction of system capacity is more obvious. Power control technology can better solve the above problems, so that the system can maintain high-quality communication without causing interference to other users. It is one of the very important key technologies in the CDMA communication system.

Power control is divided into uplink power control and downlink power control. Uplink power control plays an important role in eliminating the near-far effect, while downlink power control can reduce the average transmit power of the base station, thereby reducing the interference to neighboring cells and increasing the resources available for the downlink. The downlink power control can be divided into downlink open-loop power control in which only the mobile station participates and downlink closed-loop power control in which the mobile station and the base station participate simultaneously. When multiple users share downlink resources, if the power control technology is used, it is very beneficial to improve the utilization rate of system resources and reduce interference.

The basic method of the traditional downlink closed-loop power control is that after the mobile station receives a dedicated physical channel (DPCH, Dedicated Physical Channel), it measures its SIR measurement value "SIRest value", and compares it with the target signal-to-noise ratio SIRtar value, if SIRest >SIRtar, indicating that the power transmitted by the base station is sufficient for the performance required by the UE. At this time, the UE sends a "down" command to the base station to allow the base station to reduce the transmission power; otherwise, if SIRest<SIRtar, the UE sends an "up" command to the base station to allow The base station increases transmission power. This continuous back and forth communication control process is called downlink closed-loop power control. The target signal-to-noise ratio SIRtar value is downloaded from the upper layer.

This traditional closed-loop power control method requires that the DPCH channel must continuously transmit user information, so that the mobile station can be targeted, and SIRest can be measured in each frame, and then the TPC command value is formed, and the power control can compensate for channel fading and path loss. .

Since the traditional communication system mainly serves the voice service, that is, the link is always connected during the communication process, the above traditional power control method can meet the service requirement. However, with the rapid development of communication, data communication services have an inevitable development trend. The sudden characteristics of data transmission services cannot guarantee that users can receive services in every frame, that is, when multiple users cannot continuously use downlink resources, such closed-loop power control It will not be possible, so the traditional downlink closed-loop power control algorithm can no longer meet the current development of data service communication.

Contents of the invention

The purpose of the present invention is to provide a downlink power control method when transmitting bursty data services. Through the power control method, the precision of power control can be improved, and the average transmission power of the base station can be effectively reduced, so as to reduce the interference to adjacent cells and improve the use efficiency of downlink resources.

The present invention is realized through the technical scheme that the following steps are formed:

(1) The user judges whether the information frame transmitted by the base station carries user-specific data information;

(2) If the user-specific data information is not carried, the user measures and saves the public information signal-to-noise ratio transmitted by the information frame, and enters step (4); otherwise, enters step (3);

(3) The user measures the signal-to-noise ratio of the user-specific data information, compares it with the target signal-to-noise ratio, obtains the transmission power control command, that is, the TPC command value, and uploads it to the base station, and the user saves the TPC command value, and enters step (5);

(4) The user further judges whether the previous information frame of the information frame carries user-specific data information. If the previous information frame does not carry user-specific data information, the user compares the signal-to-noise ratio of the public information transmitted by the information frame with the previous information frame. The information frame transmits the signal-to-noise ratio of the public information, obtains the TPC instruction value, and uploads it to the base station; otherwise, the user uploads the TPC instruction value of the previous information frame to the base station;

(5) After the base station receives the TPC command value uploaded by the user, it determines whether the information frame corresponding to the TPC command value carries user-specific data information. If it does not carry user-specific data information, the base station accumulates the received TPC command value Form the cumulative value of the TPC command, and when there is an information frame carrying user-specific data to be transmitted, use the cumulative value of the TPC command to adjust the transmission power of the base station to transmit the information frame carrying user-specific data; When the data information frame needs to be transmitted, the base station directly uses the received TPC command value to adjust the transmission power of the base station to transmit the user-specific data information frame.

In above-mentioned steps (4), the formation of TPC instruction value comprises the following steps when previous information frame does not carry user-specific data information:

(a) The signal-to-noise ratio of the public information transmitted by the information frame is greater than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC instruction value of the base station in the previous information frame plus a step size to obtain the TPC instruction of the information frame value;

(b) The signal-to-noise ratio of the public information transmitted by the information frame is less than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC command value of the base station in the previous information frame minus a step to obtain the TPC command of the information frame value;

(c) The signal-to-noise ratio of the public information transmitted by the information frame is equal to the signal-to-noise ratio of the public information transmitted by the previous information frame, then the TPC instruction value of the information frame is the TPC instruction value uploaded to the base station in the previous information frame.

Any information frame transmitted by the base station to the user in the above steps carries public information.

The inventive method can also be realized by the technical scheme that is made up of the following steps:

(1) The system sets the preset interval period for the user to upload the cumulative value of the public information TPC command to the base station, and the preset interval period is less than the interval period for transmitting two information frames carrying user-specific data information;

(2) The user judges whether the received information frame carries user-specific data information;

(3) If the user-specific data information is not carried, the user measures and saves the public information SNR transmitted through the information frame, and enters step (5); otherwise, enters step (4)

(4) The user measures the signal-to-noise ratio of the user-specific data information, compares it with the target signal-to-noise ratio, obtains the TPC command value and uploads it to the base station, and the user saves the TPC command value and enters step (7);

(5) The user further judges whether the previous information frame of the information frame carries user-specific data information, and if the previous information frame carries user-specific data information, the user accumulates the TPC command value of the previous information frame; otherwise, the user compares The signal-to-noise ratio of the public information transmitted by the information frame is compared with the signal-to-noise ratio of the public information transmitted by the previous information frame, and the TPC command value is obtained and accumulated;

(6) The user uploads the cumulative value of the TPC command to the base station after a preset interval;

(7) After the base station receives and saves the TPC command value or the accumulated value of the TPC command uploaded by the user, when it is determined that there is an information frame carrying user-specific data to be transmitted, use the TPC command value to adjust the base station to send the information carrying user-specific data frame transmit power.

Any information frame transmitted by the base station to the user in the above steps carries public information.

Wherein in said step (5), the formation of the TPC command value comprises the following steps when the previous information frame does not carry user-specific data information:

(a) The signal-to-noise ratio of the public information transmitted by the information frame is greater than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC instruction value of the base station in the previous information frame plus a step size to obtain the TPC instruction of the information frame value;

(b) The signal-to-noise ratio of the public information transmitted by the information frame is less than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC command value of the base station in the previous information frame minus a step to obtain the TPC command of the information frame value;

(c) The signal-to-noise ratio of the public information transmitted by the information frame is equal to the signal-to-noise ratio of the public information transmitted by the previous information frame, then the TPC instruction value of the information frame is the TPC instruction value uploaded to the base station in the previous information frame.

The main difference between the above two methods for realizing the present invention is: during the continuous transmission of information frames that only carry public information, the first method is to complete the accumulation process of the public information TPC command value at the base station side, and the user returns continuously Uplink signaling of the TPC command value; the second method is to complete the accumulation of the public information TPC command value on the user side, and upload the accumulated value of the TPC command at an interval preset by the system.

The present invention measures the signal-to-noise ratio of the public information during the transmission interval of the special data information by the user, and compares it to form a TPC command, and accumulates the TPC command value to form the accumulated value of the TPC command. When there is user-specific data information to be transmitted, use The accumulated value of this TPC command is used to adjust the transmit power of the base station, thereby realizing approximately continuous tracking of channel fading and path loss, which can maintain high-quality communication without causing interference to other users, and overcomes the downlink closed-loop power control method in the prior art The limitations of the application in this sudden data traffic.

Description of drawings

Through the following description of the preferred embodiments of the present invention in conjunction with the accompanying drawings, various objectives, advantages and characteristics of the present invention can be further understood, wherein:

Fig. 1 is the flow chart of the power control signaling that forms the cumulative value of the public information TPC command at the base station side according to the present invention;

Fig. 2 is a flow chart of power control signaling for forming an accumulation value of public information TPC commands at the user side according to the present invention.

Detailed ways

The present invention is used when there is burst service transmission between the user and the base station, that is, when there is discontinuous transmission of user-specific data information, but the continuous transmission of public information in each information frame.

Figure 1 is a signaling flow chart of near-closed-loop power control for discontinuous downlink data services processed by the base station. For clarity, it is assumed that power control is only performed on mobile user A (UE A) in the system.

This preferred embodiment realizes downlink power control through the following steps:

(1) The base station (NodeB) transmits user-specific data information to user A (UE A) in the first information frame;

(2) After user A receives the user-specific data information, measure the signal-to-noise ratio (SIR1) of the data information, compare it with the target signal-to-noise ratio, obtain the TPC1 command value, and upload it to the base station, and user A stores the TPC1 command value in user memory;

(3) After the base station receives the TPC1 instruction value, it determines that the subsequent second information frame carries user-specific data information to be transmitted, so the base station adjusts the transmission power of the base station to transmit the second information frame with the TPC1 instruction value;

(4) User A judges that the received second information frame carries user-specific data information, repeats the above step (2), that is, measures the signal-to-noise ratio (assumed to be SIR2) of the user-specific data information, and compares it with the target signal-to-noise ratio Comparing to obtain the TPC2 command value, and uploading to the base station, at the same time user A uses the TPC2 command value to update the TPC1 command value in the user memory;

(5) After receiving the TPC2 instruction value uploaded by user A, the base station determines that the third information frame has no user-specific data information to be transmitted, and transmits the information frame carrying only public information a to user A;

(6) User A judges that the third information frame received does not carry user-specific data information, measures the signal-to-noise ratio (assumed to be SIRa) of the public information a transmitted by the frame, uploads the TPC2 instruction stored in the user memory to the base station, And update the TPC2 instruction in the user memory with the public information signal-to-noise ratio SIRa;

(7) After receiving the TPC2 command value uploaded by user A, the base station confirms that the third information frame does not carry user-specific data information, stores the TPC2 command value in the base station accumulator, and determines the fourth TPC2 command value to be transmitted by the base station side. There is no user-specific data information in the information frame, and the information frame carrying only public information b is sent to user A;

(8) User A judges that the fourth information frame received does not have user-specific data information, and measures the signal-to-noise ratio (SIRb) of the received public information b, which is compared with the third frame of public information a SNR stored in the user memory Compared with SIRa, SIRb is greater than SIRa, and the TPC3 command value is obtained that is 1 step higher than TPC2, and the TPC3 command value is uploaded to the base station, and the public information a of the third information frame is updated with the SIRb in the user memory The signal-to-noise ratio SIRa;

(9) The base station receives the TPC3 instruction value uploaded by user A, confirms that there is no user-specific data information transmission in the fourth frame, and accumulates the TPC3 instruction value and the TPC2 instruction value in the base station side accumulator to obtain the TPC instruction accumulated value (TPC2+ TPC3), while judging that the fifth frame to be transmitted on the base station side carries user-specific data information, adjust the base station transmission power with the base station side TPC command accumulation value (TPC2+TPC3);

(10) User A judges that the received fifth frame information carries user-specific data information, compares it with the target SNR, obtains the TPC4 command value, and uploads it to the base station, and user A stores the TPC4 command value in the user memory at the same time middle.

By analogy, in each information frame transmitted by the base station in the future, if user A's own dedicated data information is carried, the signal-to-noise ratio of the data information is measured, compared with the target signal-to-noise ratio to form a TPC command value, and reported to the base station.

In this embodiment, during the transmission of two information frames carrying user-specific data information, the accumulation process of the public information TPC command value is completed on the base station side.

Fig. 2 is the signaling flowchart of the near-closed-loop power control of the discontinuous downlink data service processed on the user side, this embodiment is another preferred embodiment for realizing the method of the present invention, and this embodiment is realized by the following steps Downlink power control:

(1) The system sets the preset interval period for the user (UE A) to upload the cumulative value of the public information TPC command to the base station (NodeB) (assumed to be 1 information frame);

(2) After receiving the first information frame carrying user-specific data information transmitted from the base station, user A measures the signal-to-noise ratio (SIR1) of the data information, compares it with the target signal-to-noise ratio, and obtains the TPC1 command value, and upload it to the base station, and user A stores the TPC1 command value in the accumulator on the user side at the same time;

(3) After the base station receives the TPC1 instruction value, it determines that the second information frame to be transmitted carries user-specific data information, and the base station directly adjusts the base station transmission power with the TPC1 instruction value to transmit the second information frame, and stores the second information frame in the base station side memory at the same time TPC1 instruction value;

(4) User A receives the user-specific data information, measures the signal-to-noise ratio (assumed to be SIR2) of the user-specific data information, and compares it with the target signal-to-noise ratio, obtains the TPC2 command value, and uploads it to the base station. The A-side accumulator is cleared, and the newly obtained TPC2 instruction value is stored;

(5) After the base station receives the TPC2 instruction value uploaded by user A, it detects that there is no user-specific data information to be transmitted in the third information frame, and transmits the information frame carrying only public information a to user A, and uses the TPC2 instruction value in The base station side memory updates the TPC1 instruction value;

(6) User A receives the third information frame that only carries the public information, measures the signal-to-noise ratio (assumed to be SIRa) of the public information a transmitted in the frame, and stores it in the user-side memory;

(7) The base station transmits the fourth information frame carrying only public information to user A;

(8) User A receives the fourth information frame that only carries public information b, measures the SNR of the public information (assumed to be SIRb), compares it with the SNR of the third frame of public information SIRa stored in the user memory, and obtains The TPC3 command value is accumulated with the TPC2 command value stored in the user A side accumulator to obtain the TPC command cumulative value (TPC2+TPC3), and the TPC command cumulative value is uploaded to the base station, and SIRb is used to update SIRa in the user memory;

(9) The base station receives the accumulated value of the TPC command (TPC2+TPC3), detects that there is no user-specific data information to be transmitted in the fifth frame, and transmits the information frame carrying only the public information c to user A, and simultaneously uses the accumulated value of the TPC command ( TPC2+TPC3) update the TPC2 instruction value in the base station side memory;

(10) User A receives the fifth information frame that only carries public information c, measures the public information signal-to-noise ratio of the frame (assumed to be SIRc), and updates the fourth frame public information signal-to-noise ratio SIRb in the user-side memory with SIRc;

(11) The base station detects that the sixth information frame to be transmitted carries user-specific data information, and uses the accumulated value of the TPC command (TPC2+TPC3) stored in the base station side memory to adjust the transmit power of the base station.

In this embodiment, during the interval of transmitting user-specific data information, the user measures the signal-to-noise ratio of the public information, and then forms the public information TPC instruction value, and completes the accumulation process of the public information TPC instruction value on the user side to obtain the TPC of the public information Command the accumulated value, and upload the TPC command accumulated value to the base station at a preset interval. Since the user does not need to continuously upload the TPC command value to the base station, this reduces the load on the uplink; in addition, due to the bursty nature of the data service, the accumulated value of the TPC command uploaded to the base station changes with the burst frequency of user-specific data information. It changes randomly, and it is required to ensure that the bit value of the TPC command is uploaded.

Claims (7)

1. A power control method for a code division multiple access communication system, characterized in that the method comprises the following steps: (1) The user judges whether the information frame transmitted by the base station carries user-specific data information; (2) If the user-specific data information is not carried, the user measures and saves the public information signal-to-noise ratio transmitted by the information frame, and enters step (4); otherwise, enters step (3); (3) The user measures the signal-to-noise ratio of the user-specific data information, compares it with the target signal-to-noise ratio, obtains the transmission power control command, that is, the TPC command value, and uploads it to the base station, and the user saves the TPC command value, and enters step (5); (4) The user further judges whether the previous information frame of the information frame carries user-specific data information. If the previous information frame does not carry user-specific data information, the user compares the signal-to-noise ratio of the public information transmitted by the information frame with the previous information frame. The information frame transmits the signal-to-noise ratio of the public information, obtains the TPC instruction value, and uploads it to the base station; otherwise, the user uploads the TPC instruction value of the previous information frame to the base station; (5) After the base station receives the TPC command value uploaded by the user, it determines whether the information frame carries user-specific data information. If it does not carry user-specific data information, the base station accumulates the received TPC command value to form a TPC command accumulation value , when there is an information frame carrying user-specific data to be transmitted, use the accumulated value of the TPC command to adjust the transmission power of the base station to transmit the information frame carrying user-specific data; otherwise, wait for the base station to determine that there is an information frame carrying user-specific data to be transmitted , the base station directly uses the received TPC command value to adjust the transmission power of the base station to transmit the information frame carrying the user-specific data. 2, power control method as claimed in claim 1 is characterized in that, in the step (4), the formation of TPC command value comprises the following steps when previous information frame does not carry user-specific data information: (a) The signal-to-noise ratio of the public information transmitted by the information frame is greater than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC instruction value of the base station in the previous information frame plus a step size to obtain the TPC instruction of the information frame value; (b) The signal-to-noise ratio of the public information transmitted by the information frame is less than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC command value of the base station in the previous information frame minus a step to obtain the TPC command of the information frame value; (c) The signal-to-noise ratio of the public information transmitted by the information frame is equal to the signal-to-noise ratio of the public information transmitted by the previous information frame, then the TPC instruction value of the information frame is the TPC instruction value uploaded to the base station in the previous information frame. 3. The power control method according to claim 1, wherein each information frame transmitted by the base station to the user carries public information. 4. A power control method for a code division multiple access communication system, characterized in that the method comprises the following steps: (1) The system sets the preset interval period for the user to upload the cumulative value of the public information TPC command to the base station; (2) The user judges whether the received information frame carries user-specific data information; (3) If the user-specific data information is not carried, the user measures and saves the public information SNR transmitted through the information frame, and enters step (5); otherwise, enters step (4) (4) The user measures the signal-to-noise ratio of the user-specific data information, compares it with the target signal-to-noise ratio, obtains the TPC command value and uploads it to the base station, and the user saves the TPC command value and enters step (7); (5) The user further judges whether the previous information frame of the information frame carries user-specific data information, and if the previous information frame carries user-specific data information, the user accumulates the TPC command value of the previous information frame; otherwise, the user compares The signal-to-noise ratio of the public information transmitted by the information frame is compared with the signal-to-noise ratio of the public information transmitted by the previous information frame, and the TPC command value is obtained and accumulated; (6) The user uploads the cumulative value of the TPC command to the base station after a preset interval; (7) After the base station receives and saves the TPC command value or the accumulated value of the TPC command uploaded by the user, when it is determined that there is an information frame carrying user-specific data to be transmitted, use the TPC command value to adjust the base station to send the information carrying user-specific data frame transmit power. 5, the power control method as claimed in claim 4 is characterized in that, in the step (5), the formation of TPC instruction value comprises the step when previous information frame does not carry user-specific data information: (a) The signal-to-noise ratio of the public information transmitted by the information frame is greater than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC instruction value of the base station in the previous information frame plus a step size to obtain the TPC instruction of the information frame value; (b) The signal-to-noise ratio of the public information transmitted by the information frame is less than the signal-to-noise ratio of the public information transmitted by the previous information frame, then upload the TPC command value of the base station in the previous information frame minus a step to obtain the TPC command of the information frame value; (c) The signal-to-noise ratio of the public information transmitted by the information frame is equal to the signal-to-noise ratio of the public information transmitted by the previous information frame, then the TPC instruction value of the information frame is the TPC instruction value uploaded to the base station in the previous information frame. 6. The power control method according to claim 4, wherein the preset interval in step (1) is shorter than the interval between two information frames carrying user-specific data information. 7. The power control method according to claim 4, wherein each information frame transmitted by the base station to the user carries public information.

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