CN100433579C - Estimation algorithm for signal-to-interference ratio of forward basic service channel in CDMA system in FDD mode - Google Patents

Abstract

The invention provides two algorithms for estimating the signal interference ratio of a forward basic service channel in a CDMA system in an FDD mode, which are used for realizing the power control of an inner loop and an outer loop of the forward (downlink) basic service channel in the CDMA system in the FDD mode. The first method is to estimate the signal-to-interference ratio of the forward fundamental channel by using pilot combination, and calculate the signal-to-interference ratio Eb/Nt of the forward fundamental traffic channel in the FDD mode CDMA system by using the variance of the amplitude of the combined pilot symbol in one PCG (power control group) as the interference signal power and the mean square value of the amplitude of the power control symbol in the same PCG as the signal power. The second method for estimating the signal-to-interference ratio of the forward fundamental channel is the PCB ONLY method, i.e. in a PCG, 1/2 of the square of the sum of the I, Q signal amplitudes of each PCB is used as the instantaneous power estimate of the noisy signal, and the square of the difference of the I, Q signal amplitudes of the PCB is used as the instantaneous power estimate of the noise interference, so that several instantaneous signal-to-interference ratios are calculated by using ONLY the I, Q signal amplitudes of each PCB in the PCG. And then, the average value of a plurality of instantaneous signal-to-interference ratios in the PCG is counted to obtain the estimation of the signal-to-interference ratio of the forward basic service channel of the PCG.

Description

Forward Fundamental Traffic Channel Signal-to-Interference Ratio Estimation Algorithm in FDD Mode CDMA System

Technical field:

The present invention proposes two forward (downlink) basic service channel signal-to-interference ratio estimation algorithms in the CDMA system (including cdma2000 and UMTS two kinds of systems) of FDD mode, and is used for realizing the forward (downlink) basic service in the CDMA system of FDD mode Inner-loop and outer-loop power control of the channel. The invention belongs to the technical field of mobile communication.

Background technique:

The estimation algorithm of the signal-to-interference ratio proposed by the invention is directly related to the power control technology of the forward (downlink) basic service channel of the FDD mode CDMA system.

Power control technology is the core technology of CDMA system. The CDMA system is a self-disturbing system, and all mobile users occupy the same bandwidth and frequency. If the spreading codes used by the system are not completely orthogonal (the address codes used in the actual system are approximately orthogonal), thus causing mutual interference. In a CDMA system, each code-division channel is subject to interference from other code-division channels, which is inherently inherent.

A notable feature of the CDMA system is that it can reduce the total energy of system interference as much as possible so as to improve the capacity of the system.

Power control technology is used to ensure that each signal can reduce the transmission power as much as possible under the condition of meeting the basic communication quality requirements, so as to reduce the interference to other signals. In CDMA there is no excess energy being transmitted, which is usually not possible with systems using other technologies. So power control is a key technology in resource allocation and interference suppression in CDMA wireless spread spectrum communication system.

The purpose of power control is to make the frame error rate received by the mobile station and the base station close to a target value, for example, for voice services, the target value is 1%; for data services, the target value is usually set at 5%. System capacity can be increased by selecting a higher target frame error rate while still meeting voice quality requirements. A higher target frame error rate means lower average transmit power, which enables the system to accommodate more users.

In third-generation mobile communication systems, power control must accomplish three tasks:

(1) Overcoming the near-far effect

In a cellular wireless communication system, the signal strength decays exponentially as the distance increases, and the fading index is about 4. The distance from different mobile stations to the base station may vary by 100 times. If the mobile station transmits the same power, the strength of different signals received by the base station may differ by 80dB. At this time, the distant signal will be overwhelmed by the nearby signal and cannot be correctly interpreted by the base station. Tune. This is the "near-far effect" of uplink power. Power control can overcome channel fading and maintain uniform power of each mobile signal at the base station.

(2) Overcome the multiple access effect and prevent the power ratio from rising

CDMA is a self-interference system, multiple channels occupy the same frequency band at the same time, and any channel will be interfered by other channels with different address codes, that is, "multiple access interference". From the perspective of the entire network, when the system is at a certain power stability point, any power increase will cause the power of other users to rise in comparison, resulting in a substantial increase in network interference. Power control adjusts the transmission power of the channel so that the transmission power of the entire network is at a minimum or quasi-minimum point, thereby reducing the interference level in the system and improving the system capacity.

(3) Provide higher QoS (Quality of Service)

Power control is an optimization technology. The purpose of optimization is to reduce the transmission power as much as possible while meeting the communication quality requirements (bit error rate, frame error rate), which means that for each user, both power consumption is reduced, Again, a cleaner communication environment is obtained; for the system, capacity and stability are improved.

For power control to play an important role in a CDMA system, the design of its algorithm must be based on three basic principles:

(1) Power balance. The useful signal power received by the receiving end is equalized through power control. For the uplink, the goal is to make the power of each mobile station reach the base station equal; for the downlink, the goal is to make the power of the useful signal received by each mobile station equal to the base station.

(2) The signal-to-interference ratio is balanced. The signal-to-interference ratio (C/I) received by the receiving end is equalized through power control. For the uplink, the goal is to make the C/I of each mobile arriving at the base station equal; for the downlink, the goal is to make the C/I of the useful signal received by each mobile station equal to the base station.

(3) Bit error rate (BER/FER) balance. The bit error rate at the receiving end is equalized by power control. For the uplink, the goal is to make the bit error rate of each mobile station reach the base station equal; for the downlink, the goal is to make the bit error rate of the useful signal received by each mobile station equal to the base station.

According to the direction of power transmission, power control can be divided into forward power control and reverse power control, in which reverse power control includes reverse open-loop and reverse closed-loop power control; closed-loop power control is divided into inner loop and outer loop For power control, the inner loop uses Eb/No as an indicator to adjust the power, and the outer loop uses the frame error rate as an indicator to adjust the inner loop Eb/No threshold.

Forward power control is mainly to overcome the interference of downlink signals from users in the outer cell and other users in the cell. The base station adjusts the transmit power for each mobile station according to the measurement results provided by the mobile station. Small forward transmit power; assign larger forward transmit power to those mobile stations that are far away and have low demodulation signal-to-interference ratio. At this time, power control can resist interference and compensate for channel fading. If the channel change trend can be tracked in time, ideal power control will treat the fading channel as an additive white Gaussian noise (AWGN) channel at the receiving end. The methods mainly include far-near control method and signal-to-interference ratio control method.

The reverse power control mainly solves the problem of the near-far effect. Each mobile station adjusts the transmission power to the base station in real time with the help of the power control command of the base station, so as to ensure that all signals have the same average power when they reach the base station, and just reach the communication quality. Minimum signal-to-interference ratio threshold. To this end, the system adopts the measures of combining open-loop power control and closed-loop power control.

Open-loop power control (OLPC) means that the mobile station (or base station) adjusts the transmit power of the mobile station (or base station) according to the signal power received by the forward (or reverse) link. Open-loop power control is based on consistent channel fading in uplink and downlink. Closed-loop power control (CLPC) generally means that the base station (and mobile station) generates Eb/No (bit energy/interference spectral density) according to the Eb/No (bit energy/interference spectral density) of the mobile station (or base station) signal received on the forward (or reverse) link The power control command is then transmitted to the mobile station (or base station) through the forward (or reverse) link, and the mobile station (or base station) adjusts the transmit power according to the power control command.

For the CDMA system of frequency division duplex mode (FDD), the corresponding frequency interval between the uplink and the downlink is 45MHz, which is much larger than the coherent bandwidth of the channel. Therefore, the fading of the uplink and the downlink is irrelevant , It is difficult to achieve the required control accuracy by using open-loop power control. It is generally believed that in a CDMA system in FDD mode, the function of open-loop power control is to adjust the transmit power when the mobile station initially accesses, and at the same time, it plays a certain role in compensating for the slow change of attenuation caused by path loss. In order to improve the power control accuracy and overcome the relatively fast Rayleigh fading, closed-loop power control must be adopted.

Forward closed-loop power control is also divided into inner loop power control (FILPC) and outer loop power control (FOLPC). Inner loop power control means: the mobile station compares the received Eb/No with the target value to adjust the base station transmit power. The outer loop power control means that the mobile station adjusts the setting value of the target Eb/No according to the target forward frame error rate (FFER).

In the forward inner loop power control, for cdma2000, the forward frame consists of 16 PCGs (power control groups) with a length of 1.25 ms, and for UMTS (WCDMA), the forward frame consists of 15 PCGs with a length of 0.667 ms. The mobile station measures the Eb/No of each PCG in the forward fundamental channel (F-FCH)/downlink traffic channel (DTCH). According to the results of measurement and comparison, a forward power control (FPC) command is sent to the base station by inserting a PCB (power control bit) every 1.25ms/0.667ms in the reverse pilot channel (R-PICH). If PCB=1, the base station increases its transmit power; if PCB=0, the base station uses to decrease its transmit power.

In order to realize the closed-loop power control of the forward (downlink) traffic channel, firstly, the mobile station needs to measure and calculate the signal-to-interference ratio in the forward (downlink) traffic channel. Then, if the outer loop power control is used, the mobile station compares the measured SIR with the target SIR setting value obtained from the outer loop. If the measured value is less than the target setting value, the base station is required to increase the transmit power, otherwise , the base station is required to reduce the power.

The closed-loop power control process of the forward basic channel is shown in Figure 1.

The mobile station needs to measure and calculate the signal-to-interference ratio of the channel from the received forward (downlink) QPSK modulated signal of the data bits of the basic service channel. The most direct way to calculate the signal-to-interference ratio is to obtain the mean value and variance of the QPSK signal through statistics, and then calculate the ratio of the mean square to the variance as the measurement value of the signal-to-interference ratio.

However, there are three problems here:

(1) For the forward basic traffic channel, since the symbol bits of the traffic are unknown, the modulation component of the traffic symbol chips contained in the QPSK signal is also unknown, so the mean value and variance of the traffic symbol bits cannot be estimated (later or the energy of noise interference);

(2) For the I (in-phase) and Q (quadrature) components contained in the QPSK signal, how to estimate the energy of the signal and noise (interference) therefrom is also a problem to be solved;

(3) For the CDMA system, under the premise of a certain channel bandwidth, the service transmission rate determines the spread spectrum gain, so it is directly related to the frame error rate. Therefore, in order to achieve the purpose of power control to ensure the frame error rate, the estimation of the signal-to-interference ratio needs to be completed on the premise that the channel rate is known. However, in the forward basic traffic channel, the service rate changes dynamically, which also determines that the signal-to-interference ratio cannot be calculated using the traffic symbols transmitted in the forward basic traffic channel.

Invention content:

Design purpose: in order to solve the above problems, thereby more accurately estimating the signal-to-interference ratio of the forward basic channel, the present invention proposes two algorithms for estimating the signal-to-interference ratio of the FDD pattern CDMA system forward (downlink) basic service channel, the first It is the pilot combination method, and the second is the PCB Only method.

Design solution: In order to estimate the signal bit energy Eb in the forward fundamental channel, it is necessary to estimate the power along the main components of the known rate signal. Since all bit rates in the forward fundamental traffic channel of an FDD mode CDMA system are variable except power control bits (PCBs), PCBs are the only candidate bits that can be used for this estimation. PCBs are always sent at full rate, therefore, the Eb/Nt (Nt stands for interference) obtained with PCBs can be used directly without determining the threshold according to the Eb/Nt set value.

The disturbance Nt can be estimated by one of the following two methods:

(1) Estimate the variance of the known signal. For the CDMA technology of FDD, this means the variance of the pilot signal of the same cell (cell) that provides the forward basic traffic channel for the mobile station.

(2) If possible, estimate the energy of the quadrature component of the received signal. In the CDMA technique of FDD, such quadrature components are provided for PCBs. They are always sent in pairs, thus reducing one degree of freedom of the signal. This approach also applies to receivers.

These two methods are described in detail below.

The first method is to use the combined pilot signal to estimate the signal-to-interference ratio of the forward basic channel, that is, through the combined pilot signal, use the variance of the combined pilot signal obtained by statistics to estimate the interference power Nt, and use the statistically obtained The signal power Eb is estimated by taking the mean value of the square of the amplitude of symbols transmitted on the forward fundamental traffic channel. This involves the demodulation process of the Rake receiver and Finger used in the CDMA mobile station. The details are as follows:

In a CDMA mobile station (terminal), a Rake receiver is used to process radio signals arriving at the mobile station via multipath transmission. The radio signals arriving at the mobile station through different paths often have different transmission delays, and the transmission delay is related to the transmission path of the radio signal to the mobile station. In a Rake receiver, the hardware circuit or software that demodulates a radio signal with a certain transmission delay is called a "FINGER". Usually a Rake receiver has 3 or 4 FINGERs, that is, it can demodulate 3 or 4 radio signals with different transmission delays at the same time. The Rake receiver performs timing alignment on all FINGER output signals, and then synthesizes these signals to output a signal with a signal-to-noise ratio much higher than that of a single FINGER output.

In the CDMA mobile station, the radio signal received by the antenna (transmitted by the CDMA base station) is input to different Fingers according to different delays after a series of processing such as receiving amplifier, RF down-conversion, receiving band-pass filtering, and automatic gain control. as raw I and Q signals. These original I and Q signals include business I and Q signals, and pilot I and Q signals.

The original I and Q signals of each Finger first pass through a quadrature despreader (QDS) to realize CDMA descrambling code processing. For cdma2000, PN (pseudo-random code) code is used for descrambling. For WCDMA, the Gold code is used for descrambling.

The signal descrambled by each Finger is divided into two paths, and one path is sent to the service signal recovery circuit to extract noisy service error signals. The other way is sent to the pilot signal recovery circuit to take out the noisy pilot signal. Then, for the service signal and the pilot signal, the outputs of different Fingers are respectively combined.

Before merging (combining) the outputs from multiple Fingers, it is necessary to perform different weighting processing on the outputs of different Fingers. In the signal-to-interference ratio estimation algorithm provided by the present invention, the weighting coefficient is obtained by single-pole filtering of the pilot signal, and the weighting processing of the Finger output is realized by a complex multiplier. In order to achieve this goal, a complex multiplier (2-element dot product) needs to be added to the hardware of each Finger component of the Rake receiver.

Accompanying drawing 2 is the system block diagram of estimating Eb/Nt by pilot frequency combination method. In the "Channel Estimation" module in the figure, the output of the channel estimation module is the weight coefficient. The "Complex Conjugate" (complex conjugate) is used to form a complex multiplier (provide binary for complex multiplication).

After that, the weighted output of each Finger of the service signal channel (or pilot signal channel) undergoes phase alignment and time alignment, and the DSP firmware merges the weighted outputs of all Fingers (of service or pilot frequency) to obtain the combined service signal (or pilot signal ).

After the above combination is done, an estimate of the interference Nt is calculated as the variance of the pilot signal. The combined pilot signal here is obtained by sampling once per symbol interval, expressed by the following formula:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ck</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&zeta;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Here n(k) is the AWGN noise component, ζ _p (k) is the ISI (Inter-Symbol Interference) component, C(K) is usually constant or has pseudo-stationary characteristics, noise and ISI have zero mean, IID process, near Gaussian behavior. The variance of the combined pilots is thus:

$\mathrm{<span\; class="notranslate">\; Var</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Var</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&zeta;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Var</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Similarly, the signal in the forward basic service channel can also be expressed as:

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&zeta;</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The symbols in the above formula have equivalent definitions to the corresponding symbols in (EQ1). Thus, the noise power experienced by the decoder is:

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Var</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&zeta;</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Var</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

If we assume that ζ _P ^(K) (ISI received via the pilot channel) and ζ _T ^(K) (ISI received via the forward fundamental traffic channel) are identical (or statistically identical), then we Nt can be estimated from the variation of the pilot signal:

In general, this is not a valid assumption by any means. Because, for the ISI power brought by self-interference (caused by the TX/RX filter and/or the frequency characteristic distortion of the channel), its strength depends on the power of the channel itself. Pilot channels are strong signal channels and thus tend to have more ISI. This is the shortcoming of the pilot combination method. Yet another method we propose can overcome this weakness.

Since the noise process is dynamic, only the variance of the pilot signal strength in each PCG is calculated separately, so the noise estimate is calculated by the following formula:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Calculate the mean first:

$\mathrm{<span\; class="notranslate">\; \&mu;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

In the formula, M is the number of pilot symbols in a PCG. The pilot signal strength is calculated by the following formula:.

$\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; combined</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; pilot</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; combined</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; pilot</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

In the formula, I _{combined-pilot} (k) and Q _{combined-pilot} (k) represent the in-phase and quadrature analog modulation components of the combined k-th pilot symbol respectively.

Take the mean square value of the power control symbols within a PCG period as an estimate of the symbol energy:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\underset{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; PCB</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; PCB</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

N in the formula is the number of PCBs (power control bits) in a PCG, and k _PCB represents the kth power control bit in a PCG. The energy of each power control bit is calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; combined</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; traffic</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; combined</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; traffic</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

In the formula, I _{combined-traffic} (k) and Q _{combined-troffic} (k) represent the in-phase and quadrature analog modulation components of the combined k-th traffic symbol respectively.

The estimated value of the bit energy has a bias value, which is obviously equal to Nt. Thus, an unbiased estimate of Eb/Nt is equal to:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

As for the PCB combination in the soft handover process, the mobile station receives signals transmitted from multiple base stations. In this case, it makes sense to combine the pilot signals of the given base stations and determine the variance of the Nt estimate. To perform soft handover, the mobile station receives signals from two or more base stations simultaneously and must maintain an Eb/Et estimate for each of them. This means that the above operation will be performed multiple times according to the number of base stations involved in the soft handover.

Figure 3 is a specific flow chart of estimating the SIR of the forward fundamental channel by using the pilot combination method in an actual mobile station. In this process, the pilot combination method described above is used to estimate the SIR of the forward basic channel. like:

(1) In the step "Compute Mean and Variance of Combined Pilot for this PCG", calculate the mean value and variance of the combined pilot signal; (calculate with EQ6 and EQ7 respectively)

(2) The mean value of the pilot signal is used to judge whether the power control symbol (PCB) in a PCG period can be used to calculate the estimated Eb of the symbol energy, which can be seen in the step "|PCB|<=0.25*x"; ( The average value of the pilot signal is the calculation result of EQ7)

(3) The variance of the pilot signal is used as an estimate of the interference Nt; (the calculation result of EQ6)

(4) Calculate the mean square value of the power control symbol in a PCG period in "Compute Energy-Per-Bit" as the estimated Eb of the symbol energy; (take the calculation result of EQ9)

It can be known from the above that in the process shown in Figure 3, only when the power control symbol bit amplitude is higher than 1/4 of the combined pilot bit amplitude, the power control symbol bits can be used to calculate the symbol energy estimate Eb. Otherwise, use the SIR estimate of the previous PCG as the SIR estimate of the current PCG. In the flow chart of Figure 3, every 8 PCGs make a closed-loop power control decision for the forward fundamental channel.

The second forward basic channel signal-to-interference ratio estimation method is the PCB ONLY method, which is described as follows:

The PCB Only method relies on the fact that the transmitted PCB symbols and power in each power control group are the same and transmitted simultaneously in two quadrature phases. This means that for PCB symbols, the QPSK signal reduces to a special case of BPSK. However, a standard QPSK receiver can be used to demodulate these symbols. This means that there is a noise component orthogonal to the signal axis that can be used to estimate Nt.

I and Q are the sampling values of orthogonal I and Q of the PCB symbol (after multipath). Define x and y as:

x=I+Q(EQ11)

y=I-Q(EQ12)

Denote the absolute value of the noise-free received signal component in the PCB as a, then the signal structure (ie, the amplitude range of the signal) can be expressed as:

{I, Q}={±a,±a} (EQ13)

Equivalently, on the x-y axis, the signal structure is:

$<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; \{</span><span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; a</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$

Adding the noise components n _x and _ny along the x and y directions, the noisy signal is:

$<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; \{</span><span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; a</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; )</span>$

Then the estimate of Eb can be obtained as:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 16</span>}<span\; class="notranslate">\; )</span>$

Note that due to fading and forward channel power control, a is not constant and varies in each power control group. Therefore, for the purpose of forward channel power control, only the sampling of each PCBs can be used to obtain an instantaneous estimate of the noisy signal:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 17</span>}<span\; class="notranslate">\; )</span>$

Since the noise components nx and ny are IID, the estimation of Nt only needs to count the variance of one of them.

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Var</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>{{\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 18</span>}<span\; class="notranslate">\; )</span>$

A noisy process is expected to be plausible, that is, it varies slowly with time. Therefore, a leakage estimator—a single-pole filter—is used to estimate the noise power:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; N</span>}}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; \&beta;N</span>}}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; )</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 19</span>}<span\; class="notranslate">\; )</span>$

Finally, an estimate of the signal-to-interference ratio Eb/Nt is obtained using the ratio of the Eb estimate and the Nt estimate. Afterwards, according to the set value of the inner loop power control, a threshold value is set for the estimation of the signal-to-interference ratio Eb/Nt, so as to obtain the decision function FPC(k) of the forward power control:

$\mathrm{<span\; class="notranslate">\; FPC</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; sgn</span>}<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{<span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; et</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; EQ</span>}\mathrm{<span\; class="notranslate">\; 20</span>}<span\; class="notranslate">\; )</span>$

In some wireless configurations, multiple pairs of PCBs are sent in the same PCG. However, the symbols for these PCBs are always the same. In these wireless configurations, the I and Q components of each PCB pair can be summed separately to obtain the sum of each quadrature component. The sum of these orthogonal components can be calculated according to the above equation based on the known number of PCBs.

When the mobile station is in the soft handover state involving multiple base stations, the estimation of Eb/Nt of the forward fundamental traffic channel of each base station can be done separately according to the PCB sent by the base station.

Compared with the pilot combination method, the PCB Only method has the following advantages:

(1) Very little algorithm overhead, only two square operations, one filter operation and one division operation.

(2) The whole operation can be completed in the firmware without other hardware/firmware and software modules.

(3) The pilot combination method generally includes multiple complex multiplications (one for each path) and additions, and in soft handover situations, each pilot (from the base station) needs to be processed separately. This is a much more complex process that needs to be handled at the chip level using additional hardware-specific modules. Therefore, the method is not self-contained and requires additional modules.

(4) The pilot frequency combination method depends on the estimation of the variance of the pilot frequency signal, and at the same time, it needs to estimate its mean value. This means building an additional module with 2N computing units. where N is the number of pilot symbols used by the variance estimator. The PCBOnly module does not require such computational complexity.

Compared with the pilot combination method, the disadvantage of the PCB Only estimation method is that it uses less data when estimating the Nt estimate. This results in estimates of Eb/Nt having a high variance. However, the simulation results demonstrate that the increase in the estimation variance is manageable and did not lead to any adverse consequences in the closed-loop simulation.

The PCB Only Eb/Nt estimation algorithm can be implemented using DSP firmware. The process of the PCB Only algorithm is relatively simple and consists of the following steps:

(1) Summing the orthogonal components of different PCB pairs in the same PCG and performing Σ-Δ sampling on the components.

(2) Multiplication operation (squared) to get Eb and instantaneous Nt estimates.

(3) Unipolar filtering to obtain a filtered Nt estimate.

(4) Divide Eb by Nt to obtain Eb/Nt.

(5) Counting the average value of multiple instantaneous SIRs in the PCG to obtain an estimate of the SIR of the forward fundamental service channel of the PCG.

(6) Set the Eb/Nt threshold point to obtain forward power control decision

The simulation research shows that the PCB Only algorithm is more suitable as the Eb/Nt estimation algorithm of the basic traffic channel. The reason for this choice is that it is simpler than pilot combining and the performance is very close.

Simulation studies show that there is a linear deviation between the estimated Eb/Nt value obtained by the PCB Only algorithm and the actual Eb/Nt value. In order to convert the Eb/Nt estimate obtained by the PCB Only algorithm into a target expected value, a small calibration factor needs to be estimated for this conversion. Moreover, the Eb/Nt threshold point also needs curve calibration to eliminate the estimation deviation of the PCB Only estimator. The calibrated forward power control is realized by using the calibrated Eb/Nt threshold point in the outer loop of the forward closed-loop power control. This calibration is linear, ie done by multiplying by a constant.

Technical solution 1: Calculation of the signal-to-interference ratio algorithm of the forward basic traffic channel in the FDD mode CDMA system based on the estimation of the combined pilot signal amplitude, using the variance of the combined pilot symbol amplitude in a power control group (PCG) as the interference signal power , using the mean square value of the amplitude of the power control symbol in the same PCG as the signal power to calculate the signal-to-interference ratio Eb/Nt of the forward basic traffic channel in the FDD mode CDMA system.

Technical solution 2: The method for estimating the signal-to-interference ratio of the forward basic traffic channel in the CDMA system of the FDD mode based on power control bit statistics, in a PCG, use 1/2 of the square of the I and Q signal amplitude sum of each PCB As the instantaneous power estimation of the noise-containing signal, the square of the difference between the I and Q signal amplitudes of the PCB is used as the instantaneous power estimation of the noise interference, so that several instantaneous signal interferences can be calculated using only the I and Q signal amplitudes of each PCB in the PCG Compare. Then, by counting the average value of multiple instantaneous SIRs in the PCG, an estimate of the SIR of the forward basic service channel of the PCG is obtained.

Technical solution 3: A system for calculating the signal-to-interference ratio of the forward basic traffic channel in the CDMA system of FDD mode, the radio signal transmitted by the CDMA base station received by the antenna, and the I and Q signals are demodulated by radio frequency to the orthogonal despreader The signal input terminal of (QDS) realizes CDMA de-orthogonal spread scrambling code processing, and one signal output by the quadrature de-spreader (QDS) is sent to the service signal recovery circuit, and the noisy service error signal is taken out and then input to the weighter signal end, the signal output end of the weighter to the business signal combination calculation Eb in a PCG to the divider, the other output of the quadrature despreader (QDS) is sent to the pilot signal recovery circuit, and after taking out the noisy pilot signal To the signal input end of the weighter, the signal output end of the weighter is connected to the pilot signal to combine and calculate the mean value of the pilot strength in a PCG, and then mainly calculate Nt to the divider. A complex multiplier (2-element dot product) is added to the hardware of each Finger component of the Rake receiver, the weighting coefficient is obtained by single-pole filtering of the pilot signal, and the weighting processing of the Finger output is realized by the complex multiplier. The weighted output of each Finger of the service signal channel (or pilot signal channel) is phase-aligned and time-aligned, and the DSP firmware combines the weighted outputs of all Fingers (service or pilot) to obtain a combined service signal (or pilot signal).

Compared with the background technology, the present invention has simple and convenient calculation, high calculation precision, resource saving, and easy implementation in mobile phones and embedded devices.

Description of drawings:

FIG. 1 is a schematic diagram of a forward basic channel closed-loop power control process.

Fig. 2 is a system block diagram of estimating the signal-to-interference ratio of the forward fundamental channel by the pilot combination method. In the figure, QDS represents a quadrature despread unit. The meanings of I _{combined-pilot} (k), Q combined- _pilot (k), I _{combined-traffic} (k), and Q _{combined-traffic} (k) are described in (EQ8) and (EQ10). I _{filtered-pilot} (k), Q _{filtered-pilot} (k) is the kth pilot symbol filtered by a single-pole filter, and is calculated by a formula similar to (EQ19). β _Chest is the coefficient β of the single-pole IIR (infinite impulse response) filter in (EQ19). p(k) is the pilot strength, calculated according to (EQ8). s ² (k) is the power of the traffic signal in the forward basic traffic channel, calculated according to (EQ10). μ is the mean value of the pilot signal strength in each PCG, calculated according to (EQ7).

Fig. 3 is a flow chart of estimating the signal-to-interference ratio of the forward fundamental channel by the pilot combination method.

Detailed ways:

Embodiment 1: with reference to accompanying drawing 1. Figure 1 illustrates the closed-loop power control process of the forward fundamental traffic channel. In addition to sending traffic signals (in the case of communicating with the mobile station) to the mobile station (terminal), the CDMA base station will also continuously send pilot signals, synchronization signals, and common control signals to the mobile station.

Various signals sent by the base station generally reach the mobile station through multipath fading. The mobile station uses a Rake receiver to extract the main components of the multipath transmitted signal. Each FINGER of the Rake receiver extracts a signal of a specific transmission path (corresponding to a specific time delay). A rake receiver aligns the phases of multiple FINGER output signals so that multiple FINGER outputs can be combined into one signal.

In order to implement power control on the forward (downlink) service signal, after the mobile station separates the pilot signal and the service signal from the received signal using the orthogonal channelization code, it needs to measure the signal-to-interference ratio SIR=Eb of the service signal /Nt. Eb is the service signal power, Nt is the noise interference power. After measuring the SIR value, the mobile station compares the measured SIR value with the preset signal-to-interference ratio threshold value, and if the measured value is higher than the threshold value, it notifies the base station to reduce the power, otherwise, it notifies the base station to increase the power . This is the forward inner loop power control.

If the signal-to-interference ratio threshold value of the forward inner loop power control is generated by the mobile station by calculating the frame error rate in real time, then the process of generating the signal-to-interference ratio threshold value by calculating the frame error rate is called the outer loop. . The forward power control using the outer loop is called the forward outer loop power control. As shown in Figure 1, the outer loop and forward outer loop power control are used.

Embodiment 2: with reference to accompanying drawing 2. In the accompanying drawing 2, the radio signal received by the antenna (transmitted by the CDMA base station) is input to different Finger as the original I and Q signals. These original I and Q signals include business I and Q signals, and pilot I and Q signals.

The original I and Q signals of each Finger first pass through a quadrature demodulator (QDS) to realize CDMA orthogonal descrambling code processing. For cdma2000, PN (pseudo-random code) code is used for descrambling. For WCDMA, the Gold code is used for descrambling.

The signal descrambled by each Finger is divided into two paths, and one path is sent to the service signal recovery circuit to extract noisy service error signals. The other way is sent to the pilot signal recovery circuit to take out the noisy pilot signal. Then, for the service signal and the pilot signal, the outputs of different Fingers are respectively combined.

In Figure 2, the output of the channel estimation module is used as a weight coefficient for weighting the Finger output. The "Complex Conjugate" (complex conjugate) in the channel estimation module is used to form the complex multiplier required for the weighting calculation (providing the complex multiplier with two elements to be multiplied).

Afterwards, the weighted output of each Finger of the service signal channel (or pilot signal channel) is phase-aligned and time-aligned, and the weighted output of all Fingers (service or pilot) is combined by the DSP firmware to obtain a combined service signal (or pilot signal).

After the above combination is completed, the power control bit (PCB) symbol energy s ² (k) in the forward fundamental traffic channel is calculated according to (EQ10) as the power of the traffic signal. Meanwhile, the interference strength is estimated by using the variance of the pilot signal strength within one PCG. Therefore, the pilot strength p(k) needs to be calculated according to (EQ8).

根据(EQ6)计算然后计算出

At the boundary of a PCG, calculated according to (EQ9)

Calculated according to (EQ6) and then calculate

Embodiment 3: with reference to accompanying drawing 3. Figure 3 is a specific flow chart of estimating the SIR of the forward fundamental channel by using the pilot combination method in an actual mobile station. In this process, the pilot combination method described above is used to estimate the SIR of the forward basic channel. like:

(1) In the step "calculate the energy mean and variance of the combined pilot symbols in the PCG", calculate the mean and variance of the combined pilot signals; (calculate with EQ6 and EQ7 respectively).

(2) The mean value of the pilot signal is used to judge whether the power control symbol (PCB) in a PCG period can be used to calculate the estimated Eb of symbol energy, which is in the step "PCB energy<=0.25*combined pilot symbol energy mean value?" It can be seen; (the mean value of the pilot signal is the calculation result of EQ7).

(3) The variance of the pilot signal is used as an estimate of the interference Nt; (the calculation result of EQ6).

(4) Calculate the mean square value of the power control symbols within a PCG period in "calculate the mean energy value of the PCB in the PCG" as the estimated symbol energy Eb; (take the calculation result of EQ8).

It can be seen from the above that in the process shown in Figure 3, only when the power control symbol bit amplitude is higher than 1/4 of the combined pilot bit amplitude, the power control symbol bits can be used to calculate the symbol energy estimate Eb. Otherwise, use the SIR estimate of the previous PCG as the SIR estimate of the current PCG. In the flow chart of Figure 3, every 8 PCGs make a closed-loop power control decision for the forward fundamental channel.

It should be understood that: although the above-mentioned embodiments have described the present invention in more detail, these descriptions are only illustrative of the present invention, rather than limiting the present invention, and any inventions that do not exceed the spirit of the present invention fall within the scope of the present invention. Into the protection scope of the present invention.

Claims (5)

1, the sir algorithms of Forward Fundamental Channel in a kind of fdd mode cdma system, it is characterized in that: control the variance of the combined pilot symbol amplitude among the group PCG as interfering signal power with a power, as signal power, calculate the signal interference ratio Eb/Nt of Forward Fundamental Channel in the fdd mode cdma system with the mean-square value of the power control character amplitude among the same PCG.

2, the sir algorithms of Forward Fundamental Channel in the fdd mode cdma system according to claim 1 is characterized in that noise-plus-interference power Nt adopts following formula to calculate:

${\hat{N}}_t=\underset{k=0}{\overset{M-1}{\mathrm{\&Sigma;}}}\frac{{(p\left(k\right)-\mathrm{\&mu;})}^2}{M-1};$

$\mathrm{\&mu;}=\underset{k=0}{\overset{M-1}{\mathrm{\&Sigma;}}}\frac{p\left(k\right)}{M}$

In the formula, p (k) is k combined pilot symbol amplitude among this PCG, and M is the number of pilot symbols among this PCG, and p (k) is calculated by following formula and tries to achieve: $p\left(k\right)=[I_{\mathrm{combined}-\mathrm{pilot}}^2\left(k\right)+Q_{\mathrm{combined}-\mathrm{pilot}}^2\left(k\right){]}^{1/2},$ In the formula, I _{Combined-pilot}(k), Q _{Combined-pilot}Homophase, the orthogonal simulation modulation product of k frequency pilot sign after (k) expression is made up respectively, μ is the average of the frequency pilot sign amplitude in each PCG.

3, the sir algorithms of Forward Fundamental Channel in the fdd mode cdma system according to claim 1 is characterized in that getting the mean-square value of internal power control character amplitude during the PCG, as the estimation of symbol energy:

${\hat{E}}_b=\underset{k_{\mathrm{PCB}}=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\frac{{\left(s\left(k_{\mathrm{PCB}}\right)\right)}^2}{N},$ N in the formula is the quantity of power control bit PCBs among the PCG;

The energy of each power control bit is calculated by following formula and tries to achieve:

$s^2\left(k\right)=I_{\mathrm{combined}-\mathrm{traffic}}^2\left(k\right)+Q_{\mathrm{combined}-\mathrm{traffic}}^2\left(k\right),$ In the formula, I _{Combined-traffic}(k), Q _{Combined-traffic}Homophase, the orthogonal simulation modulation product of k service symbol after (k) expression is made up respectively.

4, the sir algorithms of Forward Fundamental Channel in the fdd mode cdma system according to claim 1, it is characterized in that: in the hardware of each Finger component of Rake receiver, add 2 yuan of dot product complex multipliers, utilize the first order pole filtering of pilot signal to obtain weight coefficient, utilize complex multiplier to realize the weighted of Finger output.

5, the sir algorithms of Forward Fundamental Channel in the fdd mode cdma system according to claim 1, it is characterized in that: the weighting output of each Finger of service signal passage or pilot signal passage is through phase alignment and time unifying, and the weighting output that the DSP firmware merges whole Finger of service signal passage or pilot signal passage obtains combined traffic symbol or frequency pilot sign.

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