CN1108038C - Step regulation method for closed-loop power control in WCDMA system - Google Patents

Abstract

The invention discloses a step size adjustment processing method of closed-loop power control in a WCDMA system. The method combines fixed step size adjustment technology and variable step size adjustment technology, and can quickly and effectively track changes in the channel communication environment, and timely use different The power change adjusts the transmission power of the transmitter, which can not only effectively adjust the power control step size in harsh communication environments, but also adapt to a more stable communication environment, so as to achieve the purpose of maximizing the system capacity and can be used in WCDMA systems.

Description

A Step Size Adjustment Processing Method of Closed-loop Power Control in WCDMA System

The invention relates to a WCDMA communication system in the field of mobile communication.

Wideband Code Division Multiple Access (WCDMA) is a radio transmission technology (RTT) scheme proposed by the third generation mobile communication system standardization organization. The well-known time division multiple access (TDMA) and frequency division multiple access (FDMA) technologies are mainly used for voice and low-rate data transmission, which have certain limitations, while the code division multiple access (CDMA) modulation technology is used by a large number of system users A new communication technology adopted at that time.

The third-generation mobile communication system can provide multimedia services similar to fixed networks in mobile communication, support global roaming and have good service quality.

The WCDMA system is a co-frequency self-interference system. If each mobile station transmits signals with the same power, when the signal reaches the base station, the signal transmitted by the mobile station close to the base station is stronger than the signal transmitted by the mobile station far away from the base station, thus drowning it. , which is the so-called "near-far effect".

Typically in a cellular radio environment, radio propagation conditions are constantly changing. Both the signal received by the mobile station and the signal received by the base station are constantly changing, that is, fading. Fading can be fast or slow, and usually occurs synchronously.

Fast fading of a signal is generally caused by multipath propagation in a wireless environment, where the signal travels along several different paths between the transmitter and receiver, resulting in signal components with different phases and amplitudes that are summed, or amplified, in the receiver , or attenuation, up to tens of decibels.

The slow fading of the signal is due to the existence of factors that cause additional attenuation in the wireless transmission environment, such as buildings, etc. It changes centered on the median value of fast fading, and is much slower than the change caused by fast fading.

Closed-loop power control is a power control method based on quality in power control. It monitors the continuous strength change of the received signal caused by fast and slow fading, so that the power received by the base station is as consistent as possible to solve the "near and far effect" problem. Under the condition of quality, make the transmission power of the transmitter as low as possible.

In the WCDMA system, the control of the transmission power in the receiver can be realized through the power control command sent by the control device to the controlled transmitter. Power control commands are commands to increase or decrease the transmission power, and these commands increase or decrease the transmission power of the controlled transmitter through power control step adjustment.

In the existing WCDMA system, there are two types of power control step size adjustment methods: a fixed step size adjustment method and a variable step size adjustment method. The fixed step size adjustment method is simple to implement, but the flexibility is not enough. If the power control step size is small, it cannot effectively and quickly track changes in the channel communication environment. If the step size is large, the power value will be within the required power value. A large change in the vicinity will affect the system capacity; while the variable step size adjustment method can effectively and quickly track the change of the channel communication environment, but the implementation is more complicated.

The purpose of the present invention is to provide a method for adjusting the variable step size in closed-loop power control. The method combines variable step size adjustment technology and fixed step size adjustment technology, and can quickly and effectively track changes in the channel communication environment. The power change of the transmitter adjusts the transmission power of the transmitter, so as to achieve the purpose of maximizing the system capacity, and the realization is relatively simple.

The method for adjusting the closed-loop power control step size of the present invention is based on the standardization organization 3rd Generation Partnership Project (3GPP) suggestion (3GPP RAN 25.214 V1.2.1.(1999-09)), and the network system should at least provide adjustment to the fixed step size , optional to provide support for variable step size adjustment, that is, its equipment and control software should be compatible with fixed step size adjustment and variable step size adjustment. Depending on the support of the network system, provide control commands to decide whether to use variable step adjustment or fixed step adjustment. If the system does not support variable step adjustment, only fixed step adjustment is used. If the system supports two adjustment methods at the same time, the network administrator can flexibly choose one according to the advantages and disadvantages of the mobile environment and the requirements for system capacity.

1. Set the initial value of the adjustment step InitialStep, the initial value ranges from 0.5 decibels to 2 decibels, and the optimal value is 1 decibel.

2 The step size adjustment method is divided into two situations, namely fixed step size adjustment and variable step size adjustment:

When using fixed step size adjustment, the fixed step size FixStep generally takes a value between 0.5 decibels and 2.0 decibels, which is flexibly selected by the network system depending on the communication environment;

When using variable step adjustment, the processing steps are as follows:

①The power control command (TPC) enters the shift register with a length of n (n takes a value between 4 and 16, and the best value is 8) in sequence. TPC is a logic variable, which controls the direction of power change: that is, if TPC=0, the power emission decreases with a certain step size; if TPC=1, the power emission increases with a certain step size;

②Every time the TPC is shifted once, the elements in the shift register are summed to get the sum;

③ Determine whether the sum is greater than or equal to n-1, if so, add a step value DeltaUpA to the previous step value (the value of DeltaUpA is between 0.125 decibels and 2 decibels, the best value is 0.5 decibels), Then skip to step ⑥, and vice versa to step ④;

④ Determine whether the sum is less than or equal to 1, if so, add a step value DeltaUpB to the previous step value (the value is between 0.125 decibels and 2 decibels, the best value is 0.5 decibels), and then go to step ⑥ , otherwise go to step ⑤;

⑤The step value is subtracted from the previous step value by a step value DeltaDown (the value is between 0.125 decibels and 2 decibels, the best value is 0.5 decibels);

⑥ Synthesize the step length values from the previous steps ③, ④, and ⑤, and the result of the synthesis is one of the step values from the steps ③, ④, and ⑤ based on the judgment results of the ③, ④ steps: that is If the judgment of step ③ is true, then take the step value from step ③; if step ④ is true, then take the step value from step ④; if step ④ is false, then take the step value from step 5 to the step size value.

⑦Use the upper and lower thresholds to limit the dynamic range of the synthesized variable step value, the lower limit is 0.125 decibels to 1 decibel, and the upper limit is 2 decibels to 4 decibels. If the synthesized step size value is greater than its upper limit, then take the upper limit value; if the synthesized step size value is smaller than its lower limit, then take the lower limit value.

3 According to the control command of the network system, combine the fixed FixStep obtained by the fixed step adjustment in the second step and the variable step value obtained by the variable step adjustment: if the control command indicates that the fixed step adjustment is used, the result of the synthesis is fixed FixStep; if the control command indicates that variable step adjustment is used, the synthesized result is a variable step value; then the synthesized result is sent to the output port as the output step value.

The invention discloses a method for adjusting the closed-loop power control step length in the RTT of a WCDMA system. Compared with the prior art, the method has the following advantages: the fixed step length adjustment and the variable step length adjustment are integrated into one, and can be flexibly selected. And this variable step size adjustment method is relatively simple. If the system continuously asks to increase or decrease the power, that is, it is in an environment where the communication quality changes drastically, you can increase the feedback intensity at this time, that is, increase the step size; if the system is in an environment where the communication quality changes slowly, you can reduce the feedback intensity. i.e. reduce the step size. Therefore, this method has flexible step size adjustment, can quickly track channel changes, and has a large dynamic range of adjustment. It can not only effectively adjust the power control step size in harsh communication environments, but also adapt to relatively stable communication environments.

The present invention will be further described below in conjunction with the accompanying drawings and examples.

Fig. 1 is a structural diagram of a WCDMA system closed-loop power control device;

Fig. 2 is a flow chart of the step size adjustment processing of the closed-loop power control of the WCDMA system.

As shown in Figure 1, the multipath signal received by the receiver enters the RF front end (H100), undergoes A/D conversion, baseband filtering (H102), and then outputs symbol values through descrambling and despreading (H104) (in QPSK modulation, There are four modulation phases, each two bits are modulated on a phase, and each phase corresponds to a symbol). The TPC is multiplexed with other control symbols and data symbols, and the TPC is extracted from these symbols by demultiplexing method, and the combined TPC (H106) is sent to the step adjustment (H110) module. Whether to use variable step adjustment or fixed step adjustment is flexibly determined by the control command provided by the network system (H108) according to the advantages and disadvantages of the mobile environment and the requirements for system capacity. The step size value output by the step size adjustment is sent to the gain processing module (H112) in decibel form for processing.

Fig. 2 is a flow chart of the step size adjustment processing module (H110) of the closed-loop power control of the WCDMA system, and the input power control command TPC is sent to the left and right channels for processing at the same time.

What the left road of Fig. 2 adopts is fixed step size adjustment, and TPC command enters fixed step size adjustment module (S202), and the fixed step size value of this module output is preset value, and preset value is between 0.5 decibels～2 decibels, and the most A good value is 1 dB. The output fixed step value enters the step value synthesis step (S222) for use.

The right path in Figure 2 uses a variable step size adjustment:

Step (S204), TPC order enters the shift register that length is n;

Step (S206) sums the elements in the shift register sum;

Step (S208) judges "sum≥n-1":

If it is "Y", then enter step (S210) to adjust the step size, and the step size adds a step value DeltaUpA on the previous step size value; then the step size value is sent into step (S218) to perform step size adjustment synthesis;

If it is "N", proceed to step S212 to make a judgment on "sum≤1"; if it is "Y", proceed to step S214, add a step value DeltaUpB to the previous value of the step size, and then send the step value to Enter step (S218), carry out step size value synthesis;

If "sum≤1" is "N", then proceed to step (S216), make the step value subtract a step value DeltaDown on the basis of the previous step value, then send the step value to step (S218) for Step value synthesis;

Step S220 limits the dynamic range of the step size value, if the composite step size value is greater than the upper limit of the dynamic range, then make the composite step size value the upper limit; if the composite step size value is less than the lower limit of the dynamic range, then make the composite step size value be lower limit.

Step S222, receiving the processing result of step S220, together with the step value sent in step S202, performing step value synthesis again. This time the step value is synthesized by the network system control command sent by the network system to determine which method to use to generate the step value.

Step S224, finally outputting the step value after multiple synthesis, and sending it to the gain processing module H112.

The value ranges and optimal values of the above variables are:

The value of InitialStep is between 0.5 decibels and 2 decibels, and the best value is 1 decibel;

The value of DeltaUpA is between 0.125 decibels and 2 decibels, and the best value is 0.5 decibels;

The value of DeltaUpB is between 0.125 decibels and 2 decibels, and the best value is 0.5 decibels;

The value of DeltaDown is between 0.125 decibels and 2 decibels, and the best value is 0.5 decibels;

According to the needs of each WCDMA system and specific application environment, the value of each parameter can be flexibly selected.

Claims (6)

1. The step-length of closed power control is adjusted processing method in 1 one kinds of WCDMA systems, and its input parameter the network system control command that provided by network system is provided and by the power control command that receiver provides, it is characterized in that:

   The treatment step that closed power control step-length is adjusted is as follows:

   (1) step-length is set and adjusts initial value, the span that step-length is adjusted initial value is: between 0.5 decibel～2.0 decibels;

   (2) step length regulating method in two kinds of situation, i.e. fixed step size adjustment and variable step size adjustment:

   When adopting fixed step size to adjust, the span of fixed step size is: between 0.5 decibel～2.0 decibels;

   When adopting variable step size to adjust, its treatment step is as follows:

   1. power control command enters the shift register that length is n in turn, and it is a logical variable, and it has controlled the direction of variable power, and promptly power emission is to reduce or increase with certain step-length with certain step-length;

   2. the every displacement of power control command once to the summation of the element in the shift register, obtains sum;

   3. whether judge sum more than or equal to n-1,, jumped to for the 6. step then if then step value adds a step value on previous step value, otherwise to the 4. step;

   4. whether judge sum smaller or equal to 1, if then step value adds a step value on previous step value, then to the 6. step, otherwise to the 5. step;

   5. step value deducts a step value on previous step value;

   6. 3., 4., 5. the step value that comes is synthetic each step with the front, its synthetic result be by the 3., 4. the judged result in step get 3., 4., 5. some values in the step value that comes of each step: even the 3. the step be judged as very, then get the 3. step value that come of step; If the 4. the step is then got the 4. step value that come of step for true; If the 4. the step is then got the 5. step value that come of step for false;

   7. use the dynamic range of the synthetic variable step size value of Xiamen limit value restriction;

   (3) according to the network system control command, the variable step size value that fixed step size that adjustment obtains to fixed step size and variable step size adjustment obtain is synthetic once more: if the fixed step size adjustment is adopted in the control command indication, then He Cheng result is the fixed step size value; If the variable step size adjustment is adopted in the control command indication, then He Cheng result is the variable step size value, and the result that will synthesize delivers to output port as the output step value then.
2. The step-length of closed power control is adjusted processing method in the 2 WCDMA as claimed in claim 1 systems, it is characterized in that: to adjust the optimum value of initial value be 1 decibel to step-length in the treatment step (1); The optimum value of the fixed step size in the treatment step (2) is 1 decibel; The span of variable step size value is: the Xiamen is limited to 0.125 decibel～1 decibel, can be the value in this scope; Being limited to 2 decibels～4 decibels to the doorstep, can be the value in this scope.
3. The step-length of closed power control is adjusted processing method in the 3 WCDMA as claimed in claim 1 systems, and it is characterized in that: the span that is used for the step value of variable step size adjustment is between 0.125 decibel～2 decibels.
4. The step-length of closed power control is adjusted processing method in the 4 WCDMA as claimed in claim 3 systems, and it is characterized in that: the optimum value that is used for the step value of variable step size adjustment is 0.5 decibel.
5. The step-length of closed power control is adjusted processing method in the 5 WCDMA as claimed in claim 1 systems, and it is characterized in that: the length of shift register is 4～16.
6. The step-length of closed power control is adjusted processing method in the 6 WCDMA as claimed in claim 5 systems, and it is characterized in that: the optimum value of shift register length is 8.

Images