CN1250030C - Method and device for determining base station transmission diversity mode - Google Patents

Abstract

The invention provides a method and a device for determining a data downlink transmission diversity mode of a base station. The present invention first estimates a first feedback weight of the mobile unit in a first time slot, the first feedback weight having a first feedback phase (phase). Then, a second feedback weight of the mobile unit in the second time slot is estimated, the second feedback weight having a second feedback phase. And comparing the absolute phase difference of the first feedback phase and the second feedback phase, and determining whether the data downlink mode of the base station uses the closed loop transmission diversity or not according to the absolute phase difference. In addition, the invention also provides a method for determining whether the data downlink mode of the base station uses the closed loop transmission diversity by using the correctness of the closed loop adjustment result.

Description

Method and device for determining base station transmission diversity mode

technical field

The present invention relates to a method and system for determining a data transmission mode in a mobile wireless communication system, in particular to a method and a device for a mobile unit to determine a data downlink transmission diversity (down link) mode of a base station.

Background technique

In recent years, the position of spread spectrum communication system (spread spectrum communication system) in cellular mobile communication network (Cellular Mobile Communication network) and cellular mobile communication network (Cellular Mobile Communication network) has become increasingly important. In particular, Direct Sequence Code Division Multiple Access (DSCDMA) has become the standard for third-generation mobile communications.

Improving downlink capacity (downlink capacity) is one of the main challenges of the third generation mobile communication. In wireless communication systems, transmit diversity (Transmit Diversity) technology is a low-cost method that can improve downlink capacity, and transmit diversity technology has become an indispensable technology in the third generation mobile system. Transmission diversity technology In order to reduce the interference between the downlink channels and better match the downlink signal with the reception of the mobile station, the downlink channel uses multiple groups of orthogonal antennas when transmitting, and sends a different modulation signal of one kind of information. This method is called diversity transmission.

In the transmit diversity transmission technology, there are two common methods of downlink transmit diversity, which are respectively used in open loop (open loop) transmit diversity and closed loop (close loop) transmit diversity. The open-loop transmit diversity mode uses the "Space-Time block coding" (Space Time block coding) method and the full diversity (Full diversity) that uses multiple groups of transmit antennas. The antennas must be separated by sufficient distances to utilize the data received by different antennas. Signal attenuation (fading) can be regarded as an independent feature to increase antenna gain; closed loop transmission diversity mode has two sub-modes, both sub-modes are used in two sets of transmission antennas and use downlink channel measurement (downlink channel measurement) and Feedback signaling controls the phase and/or gain of the transmitted signal in the transmit antenna.

3. Contents of the invention

However, closed-loop transmission diversity can generally only be applied in the user's low-speed driving environment, and in the high-speed driving environment (when the speed exceeds 40, 50 kilometers per hour), the signal changes too fast in the transmission channel, which makes the signal attenuation ( signal fading), the inaccurate channel estimation will degrade the performance of the system using closed-loop transmit diversity.

The present invention provides a method for a mobile unit to determine a data transmission diversity mode of a base station in a wireless communication system, comprising: (A) estimating a first feedback weight of the mobile unit in a first time slot, the first feedback weight having a first feedback phase; (B) estimating a second feedback weight for the mobile unit in a second time slot following the first time slot, the second feedback weight having a second feedback phase; and (C) combining the first feedback phase and The second feedback phase determines the data transmission diversity mode of the base station; wherein the step (C) further includes: (D) comparing the first feedback phase and the second feedback phase to obtain an absolute phase difference; and (E) by The absolute phase difference determines the data transmission diversity mode of the base station; wherein step (E) further includes: (F) when the absolute phase difference is greater than a first predetermined value, increasing the judgment value by a first value, when the absolute phase difference When the judgment value is smaller than the first predetermined value, decrease the judgment value by a second value; and (G) when the judgment value is greater than the second predetermined value, send a closed-loop transmission diversity mode instruction to the base station.

The present invention provides a device for a mobile unit to determine the data transmission diversity mode of a base station in a wireless communication system, comprising: an estimating unit for estimating a first feedback weight of the mobile unit in a first time slot, the first feedback weight has a first feedback phase, and estimate the second feedback weight of the mobile unit in the second time slot, the second feedback weight has a second feedback phase; and a decision unit, based on the first feedback phase and the second feedback phase, determines the base station's Data transmission diversity mode; wherein the decision unit further includes: a comparison unit, comparing the first feedback phase and the second feedback phase, to obtain an absolute phase difference; a weighting unit, when the absolute phase difference is greater than a first predetermined value, the weighting unit The unit increases the judgment value by a first value, and when the absolute phase difference is smaller than the first predetermined value, the weighting unit decreases the judgment value by a second value; and the sending unit, when the weighted value is greater than a second predetermined value, The sending unit sends an instruction to terminate the closed-loop transmission diversity mode to the base station.

The invention provides a method and a device for a mobile unit to determine the feasibility of a transmission diversity mode of a base station in a mobile wireless communication system. Through the pilot bit (Pilot Symbol) of the dedicated physical channel (Dedicated Physical Channel) of the base station and the channel signal of the common pilot channel (common pilot channel) of the base station, the present invention can observe the change of the channel signal. If the change rate of system channel signal attenuation is too fast or the feedback error rate is too high, the base station is instructed to close the closed loop transmission diversity mode to obtain better performance.

The invention provides a method for a mobile unit to determine the data downlink mode of a base station. Firstly, the first feedback weight of the mobile unit in the first time slot is estimated, and the first feedback weight has a first feedback phase. Also, a second feedback weight for the mobile unit in a second time slot is estimated, the second feedback weight also having a second feedback phase. Finally, the data downlink mode of the base station is determined by the calculation of the first feedback phase and the second feedback phase.

The invention provides another method for the mobile unit to determine the downlink mode of the base station. First, the present invention calculates the reply weight of the base station in the same time slot, and the reply weight has a reply phase. Also, the present invention estimates the mobile unit's feedback weight for a time slot, the feedback weight having a feedback phase. Finally, the data downlink mode of the base station is determined by the calculation of the feedback phase and the reply phase.

The present invention also provides a device for a mobile unit to determine a data downlink mode of a base station in a mobile wireless communication system, including an estimation unit and a determination unit. The estimating unit estimates a first feedback weight of the mobile unit in the first time slot, the first feedback weight having a first feedback phase. The estimating unit estimates a second feedback weight of the mobile unit in a second time slot, the second feedback weight having a second feedback phase. The decision unit determines the data downlink mode of the base station according to the calculation of the first feedback phase and the second feedback phase.

The present invention further provides a device for a mobile unit to determine the downlink mode of a base station in a mobile wireless communication system, including an estimation unit, a calculation unit and a determination unit. The estimation unit estimates the feedback weight of the mobile unit in the same time slot, and the feedback weight has a feedback phase. The calculation unit calculates the reply weight of the base station in the same time slot, and the reply weight has a reply phase. The decision unit determines the data downlink mode of the base station by calculating the feedback phase and the reply phase.

Description of drawings

Figure 1 is a block diagram of a transmit diversity closed loop system.

Fig. 2 is a flowchart of a method for calculating feedback weighting parameters.

FIG. 3 is a flowchart of a method for determining a data transmission diversity mode of a base station according to the present invention.

FIG. 4 is a flow chart of another method for determining the data transmission diversity mode of the base station according to the present invention.

FIG. 5 is a device for determining the data transmission diversity mode of the base station according to the present invention.

FIG. 6 is another device for determining the data transmission diversity mode of the base station according to the present invention.

Component designation description

100 base station 101 dedicated physical channel

110 mobile unit 1051, 1053 antenna

500 Embodiment of the present invention 501 Estimation unit

503 decision unit 5031 comparison unit

5033 weighting unit 5037 sending unit

600 Embodiment of the present invention 601 Estimation unit

603 Calculation unit 605 Decision unit

6051 Comparison Unit 6053 Weighting Unit

6057 sending unit

Detailed ways

The present invention provides a method and device for the mobile unit to estimate the downlink signal of the base station in the mobile wireless communication system, feed back the weight to the base station, and make the base station determine the data transmission diversity mode, so as to improve the performance of the system.

Figure 1 illustrates a block diagram of a transmit diversity closed loop system. As shown in FIG. 1 , the user's signal sent on the dedicated physical channel 101 at the base station 100 is multiplied by the spread/identification code (spread/scramblecode) 102, and then multiplied by the feedback weighting parameters (feedback weight factor) W ₁ and W ₂ , the feedback weighting parameters form a weight vector (weight vector), generally speaking, the feedback weight vector is a complex signal. Then add the first common pilot channel C ₁ and the second common pilot channel C ₂ respectively, and then send them out through the antenna 1051 and the antenna 1053 . The mobile unit 110 can determine the feedback weight by the received signal, and the base station 100 receives the feedback weight to adjust the phase and gain of the signal transmitted by the antennas 1051 and 1053, so that the signal-to-noise ratio (SNR) of the signal transmitted by the base station 100 can be adjusted. )to reach maximum.

After the mobile unit end 110 receives the signal sent by the base station end, the channel characteristic P after adding the weight is calculated to be the maximum value to obtain the feedback weight w,

P＝w ^H H ^{H H} Hw

H=[h ₁ , h ₂ ], w=[w ₁ , w ₂ ] ^T , h ₁ and h ₂ are the channel impulse responses transmitted from the antennas 1051 and 1053 to the user end. After estimating the h ₁ and h ₂ values sent by the antenna, the eigenvalue (eigenvalue) of the autocorrelation matrix (channel autocorrelation matrix) R=H ^H H can be obtained, and the optimal feedback weighting parameter is the corresponding channel autocorrelation matrix R=H Eigenvector (eigenvector) w _f (n) of the largest eigenvalue of ^H H = [w ₁ , w ₂ ]. Finally, the eigenvector [w ₁ , w ₂ ] is sent back to the base station for the base station 100 to adjust the phase and gain of the signals sent by the antennas 1051 and 1053 .

Fig. 2 is a flowchart of a method for calculating feedback weighting. First, assume that the starting time slot n is 0 (step 201). Calculate the P value (step 203). Then calculate the largest eigenvalue of the R value, that is, the corresponding eigenvector w _f (n)=[w ₁ , w ₂ ] (step 205 ). Send this feature vector w _f (n)=[w ₁ , w ₂ ] to the base station (step 207 ). Finally, after waiting for one time slot, make n become n+1 (step 209).

Due to the closed-loop transmission diversity technology in the high-speed driving environment of the user, the feedback eigenvector is periodic timing feedback. In the high-speed environment of the mobile station, the feedback is relatively delayed in signal attenuation, so the closed-loop transmission diversity technology is reduced. system performance, the invention provides a method for determining the data transmission diversity mode of the base station.

FIG. 3 is an embodiment of the method for determining the feasibility of the transmission diversity mode of the base station according to the present invention. In this way, the present invention observes the change amount of the channel signal phase, that is, determines the data downlink mode of the base station according to the comparison between the judgment value P _th and the second predetermined value. First, assume that the starting time slot n is 0 (step 301). After waiting for one time slot, make n become n+1 (step 303). A feedback weight W(n) for the mobile unit at time slot n is estimated, the feedback weight W(n) having a feedback phase P(n) (step 305). Next, estimate the feedback weight W(n+1) of the mobile unit in the next time slot n+1, the feedback weight W(n+1) also has the feedback phase P(n+1) (step 307). Comparing the feedback phase P(n) and the feedback phase P(n+1) to obtain the absolute phase difference (step 309 ). When the absolute phase difference is greater than the preset first predetermined value, the judgment value P _th is increased by the first value, and when the absolute phase difference is smaller than the first predetermined value, the judgment value P _th is decreased by the second value (step 311 ). In this embodiment, the first value is equal to the second value.

Next, compare whether the judgment value P _th is greater than a second predetermined value (step 313 ). If the judgment value _Pth is greater than the second predetermined value, an instruction to terminate the closed-loop mode is sent to the base station (step 315), indicating that the characteristics of the channel change rapidly due to the fast speed of the vehicle and cause the phase change to be too fast. At this time, the closed-loop mode of the base station needs to be terminated Signal. If the judging value P _th is smaller than the second predetermined value, return to step 303 .

In addition, the closed-loop mode signal of the base station uses the feedback eigenvector of the mobile station to determine the feedback weight. However, if the feedback weight is due to the high-speed environment of the mobile station, the feedback weight is a wrong value, so the closed-loop transmission diversity technology On the contrary, the performance of the system is reduced, and the present invention also determines the data transmission diversity mode of the base station by observing the signal feedback error rate.

As shown in FIG. 4, the present invention assumes that the initial time slot n is 0 (step 401). After waiting for one time slot, make n become n+1 (step 403). After that, the present invention calculates the estimated adjusted weighted value W _t of the pilot bit (Pilot Symbol) of the dedicated physical channel (DedicatedPhysical Channel) of the base station and the channel signal of the common pilot channel (commonpilot channel) of the base station in the time slot (n) (step 405), the weighted value has a phase P _t (n). Next, estimate the feedback weight W _f (n) of the mobile unit in the same time slot, the feedback weight W _f (n) has a feedback phase P _f (n) (step 407 ).

The present invention compares the feedback phases P _f (n) and P _t (n) to obtain the absolute difference P _d (n) of the phase difference (step 409 ). When the absolute phase difference P _d (n) is greater than the first predetermined value, the judgment value is increased by the first value, and when the absolute phase difference P _d (n) is smaller than the first predetermined value, the judgment value is reduced by the second value (step 411). In this embodiment, the first value is equal to the second value. Next, compare whether the judgment value is greater than a second predetermined value (step 413). If the judgment value is greater than the second predetermined value, the mobile unit sends a command to terminate the closed loop mode to the base station (step 415), instructing the base station to terminate the closed loop mode. If the judging value is smaller than the second predetermined value, return to step 403 .

The invention also provides a device for the mobile unit to determine the data downlink mode of the base station in the wireless communication system. As shown in FIG. 5 , the present invention 500 includes an estimation unit 501 and a decision unit 503 . The estimation unit 501 estimates a first feedback weight of the mobile unit in a first time slot, and the first feedback weight has a first feedback phase. The estimation unit 501 further estimates a second feedback weight of the mobile unit in the second time slot, and the second feedback weight has a second feedback phase. The determining unit 503 determines the data transmission diversity mode of the base station according to the first feedback phase and the second feedback phase.

The decision unit 503 further includes a comparison unit 5031 , a weighting unit 5033 and a sending unit 5037 . The comparison unit 5031 compares the first feedback phase with the second feedback phase to obtain an absolute phase difference. When the absolute phase difference is greater than a first predetermined value, the weighting unit 5033 increases the judgment value by a first value. When the absolute phase difference is smaller than the first predetermined value, the weighting unit 5033 decreases the judgment value by a second value. When the judging value is greater than the second predetermined value, the sending unit 5037 sends an instruction to terminate the closed loop mode to the base station, instructing the base station to terminate the closed loop transmit diversity mode.

In addition, the present invention further provides a device for a mobile unit to determine a downlink mode of a base station in a wireless communication system, as shown in FIG. 6 . The device 600 includes an estimation unit 601 , a calculation unit 603 and a decision unit 605 . The estimation unit 601 estimates the feedback weight of the mobile unit in the time slot, the feedback weight has a feedback phase. The calculation unit 603 calculates the reply weight of the base station in the time slot, and the reply weight has a reply phase. The return weight is the absolute phase difference between the pilot symbols of the dedicated physical channel of the base station and the channel signal of the common pilot channel of the base station. The determining unit 605 determines the data transmission diversity mode of the base station according to the feedback phase and the reply phase.

The decision unit 605 further includes a comparison unit 6051 , a weighting unit 6053 and a sending unit 6057 . The comparing unit 6051 compares the feedback phase and the reply phase to obtain an absolute phase difference. When the absolute phase difference is greater than the first predetermined value, the weighting unit 6053 increases the judgment value by the first value. When the absolute phase difference is smaller than the first predetermined value, the weighting unit 6053 decreases the judgment value by a second value. When the judging value is greater than the second predetermined value, the sending unit 6057 sends a closed loop mode termination signal to the base station, instructing the base station to terminate the closed loop transmission diversity mode.

From the detailed description of the preferred specific embodiments above, it is hoped that the characteristics and spirit of the invention can be described more clearly, and the preferred specific embodiments disclosed above do not limit the scope of the present invention. On the contrary, the above description and various changes and similar arrangements are within the protection scope of the present invention. Therefore, the scope of the claims of the present application should be interpreted in the broadest way based on the above description, and cover all possible similar changes and similar arrangements.

Claims (3)

1. A method for a mobile unit to determine a data transmission diversity mode of a base station in a wireless communication system, comprising: (A) estimating a first feedback weight for the mobile unit in a first time slot, the first feedback weight having a first feedback phase; (B) estimating a second feedback weight for the mobile unit for a second time slot following the first time slot, the second feedback weight having a second feedback phase; and (C) Determining the data transmission diversity mode of the base station from the first feedback phase and the second feedback phase; wherein step (C) also includes: (D) comparing the first feedback phase with the second feedback phase to obtain an absolute phase difference; and (E) Determine the data transmission diversity mode of the base station according to the absolute phase difference; Wherein step (E) further comprises: (F) when the absolute phase difference is greater than a first predetermined value, increase the judgment value by a first value, and when the absolute phase difference is smaller than the first predetermined value, decrease the judgment value by a second value; and (G) When the judgment value is greater than a second predetermined value, sending an instruction to terminate the closed-loop transmit diversity mode to the base station. 2. The method of claim 1, the first value is equal to the second value. 3. A device for determining the data transmission diversity mode of a base station by a mobile unit in a wireless communication system, comprising: an estimating unit that estimates a first feedback weight of the mobile unit in a first time slot, the first feedback weight has a first feedback phase, and estimates a second feedback weight of the mobile unit in a second time slot, the second feedback weight having a second feedback phase; and A decision unit, based on the first feedback phase and the second feedback phase, to determine the data transmission diversity mode of the base station; wherein the decision unit further includes: a comparison unit, for comparing the first feedback phase and the second feedback phase to obtain an absolute phase difference; A weighting unit, when the absolute phase difference is greater than a first predetermined value, the weighting unit increases the judgment value by a first value, and when the absolute phase difference is smaller than the first predetermined value, the weighting unit decreases the judgment value by a second value; and A sending unit, when the weighted value is greater than a second predetermined value, the sending unit sends an instruction to terminate the closed-loop transmission diversity mode to the base station.

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