RU2456772C2 - Device and method to transfer and receive data during bumpless service transfer in wireless communication system - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: in the method of data reception during bumpless transfer of service in a wireless communication system, a mobile station receives a sequence of the first basic station generated by interleaving of sent data using the first template of the interleaving module, and also receives a sequence of the second basic station generated by means of interleaving of sent data using the second module of the interleaving module. Then the mobile station combines and decodes the sequence of the first basic station and the sequence of the second basic station prior to reception of the entire frame, having a sequence of the first basic station dedicated to it.

EFFECT: increased efficiency of packet transfer.

18 cl, 31 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a wireless communication system, and more particularly, to a device and method for transmitting and receiving data in soft handoff of a wireless communication system.

State of the art

First, prior art power control technology is described.

Power control in a mobile communication system is referred to as a technology that controls the power level of the received signal at the receiving side so that the system can be adjusted to the level required by modulation and coding methods that are adapted according to the transmission rate of the transmitted data. In particular, power control refers to resolving the near-far problem that occurs in the reverse link. More specifically, by controlling the transmit power of the mobile stations so that the transmit power of the mobile station near (or closer to) the base station is different from the mobile station remote from the base station, the power level of each mobile station received by the base station can be controlled to a specific level .

The mobile station transmits a power signal along with a data signal through a reverse link. Herein, reverse link power control is performed by controlling the transmit power of the mobile station so that the receive energy of the reverse pilot channel (R-PICH) can be constant. The receiving side of the base station measures the reception energy of the reverse pilot channel. Then, when the reception energy exceeds a predetermined value, which is a predetermined reference energy level, the receiving side of the base station transmits a lower power control (PCB) bit command, which means lower transmit power, to the mobile station. Also, when the reception energy is lower than a predetermined value, the receiving side of the base station transmits a power control bit (PCB) command for increase, which means an increase in transmit power, to the mobile station via the direct power control sub-channel (F-PCSCH).

Based on such pilot channel power control, reverse traffic channel (R-TCH) power control is performed in which data is transmitted via the reverse link. More specifically, the transmit power of the reverse traffic channel is determined by using the relationship between the transmit power of the pilot channel and the transmit power of the traffic channel (traffic power ratio, TPR). The TPR for each data rate transmitted over the traffic channel is determined in advance, and the transmit power of the pilot channel varies in PCB units based on reverse link power control. Thus, the relationship between the variable transmit power of the pilot channel and the predetermined TPR determines the transmit power of the traffic channel through which data is transmitted.

Further in this document, a hybrid automatic retransmission request method (hereinafter referred to as HARQ) and prior art packet data termination technology are described in detail.

The HARQ method, which is used to increase the transmission efficiency of packet data that has characteristics less sensitive to transmission delay, consists of a combination of the traditional method of direct error correction (hereinafter referred to as FEC) and the method of automatic request for retransmission (ARQ ) through error detection. The HARQ method is used in connection with the physical layer, and the HARQ method combines retransmitted data with previously received data, thereby providing a high percentage of successful decoding attempts. More specifically, the HARQ method corresponds to a method that stores data whose transmission is unsuccessful, instead of discarding a non-transmitted packet, which is then combined with the retransmitted data and thus decoded.

According to the HARQ method, the transmitting side performs FEC encoding of information with data packets in order to divide the encoded bits into multiple subpackets and transmit subpackets.

The subpacket may be decoded by using one subpacket and has a structure indicating successful / unsuccessful transmission attempt. In addition, the receiving side combines the previously received subpacket of the identical packet with the currently received subpackets and decodes the combined packets to verify a successful or unsuccessful transmission attempt. After transmitting the first subpacket, the transmitting side receives an acknowledgment (ACK / NACK) from the receiving side. Further, if the acknowledgment is a denial of reception (hereinafter referred to as NACK), another subpacket is further transmitted. Also, if the acknowledgment is an affirmative (or positive) acknowledgment (hereinafter referred to as ACK), the transmission of the corresponding packet is completed.

If N subpackets are formed using the HARQ method, when the transmitting side transmits the Mth subpacket (M <N) and receives feedback via ACK, the transmitting side completes the transmission of the corresponding packet without transmitting the remaining subpackets. This method is referred to as an early termination method. When using the early termination method, since redundant subpackets are not transmitted, the efficiency of packet transmission can be significantly improved.

Further in this document, a method for early termination in a prior art circuit channel is described in detail.

A voice (or audio) transmission service that is sensitive to transmission delay and generates adjacent data is transmitted through a circuit channel. A circuit channel is a form of channel that transmits data without interruption.

Figure 1 illustrates a reverse link power control method in a CDMA2000 system.

As shown in FIG. 1, in a code division multiple access (CDMA) 2000 system that is currently widely used, a traffic channel frame having a circuit channel structure generally corresponds to 20 ms. Each frame includes 16 time slices, and each time slot corresponds to 1.25 ms. Since the receiving side transmits one PCB for each time slot, each time slot is referred to as a power control group (PCG).

In order to increase the transmission efficiency of a traffic channel having a circuit channel structure, the standardization organization, as part of a third-generation partnership project 2 (3GPP2), is currently discussing whether or not to use the early termination method in circuit channels. In contrast to the traditional method of instructing the receiving side to receive an entire frame of 20 ms and then decoding the data, the early termination method in the circuit channels attempts to decode the data during frame reception. Accordingly, if the data reception is successfully completed, the transmitting side sends feedback via ACK, thereby interrupting the transmission of the corresponding frame.

Since this method interrupts (or stops) unnecessary transmissions in the CDMA system, interference to other users can be reduced. Thus, the total throughput (or size) of the system can increase.

Figure 2 illustrates an example application of a method for early termination in a reverse link traffic channel. Referring to FIG. 2, the base station attempts to decode data during frame reception. Then, when the data is successfully received, the base station transmits ACK feedback to the mobile station through the forward acknowledgment sub-channel (F-ACKSCH). Then, after the ACK is received, the mobile station stops transmitting the corresponding frame.

In soft handoff, a mobile station receives traffic channels carrying identical information from two or more base stations. Then, the mobile station demodulates the traffic channels received from each of two or more base stations, and combines the demodulated traffic channels, thereby performing decoding.

In a CDMA system, traffic channels transmitted by one base station are differentiated (or identified) by a spreading code. More specifically, the base station allocates different Walsh codes to each of the traffic channels. The base station then modulates the signal by using the extracted Walsh codes, thereby transmitting the modulated signal. Here, in order to transmit multiple traffic channels without interfering with each other in the same base station, the coding rate for the FEC channel coding in the traffic channel must be high. In the CDMA2000 system, in the case of radio configuration 4, the coding rate for the FEC channel coding in the forward link traffic channel is 1/2.

When the encoding rate is 1/2, when the early termination method is applied, decoding can succeed at the decoding attempt point only when at least half or more of the 20 ms frame is received. In other words, the percentage of successful decoding attempts when less than half the frame is received is 0.

Therefore, the problem is that the gain in the early termination method cannot increase.

SUMMARY OF THE INVENTION

Technical challenge

As described above, the prior art method is disadvantageous in that the early termination method cannot be improved.

The purpose of the present invention, designed to solve the problem, is to propose a method for transmitting and receiving data in soft handoff, which can increase the coding efficiency and benefit from early termination.

The technical objectives that must be realized and achieved in accordance with the present invention are not limited only to the technical objectives specified in the description set forth herein. Other technical objectives that are not indicated in this document should become apparent to specialists in this field of technology after studying the following or can be recognized from the detailed description and claims, as well as the accompanying drawings.

Technical solution

In order to achieve the objective of the present invention, according to an aspect of the present invention, in a method for receiving mobile station data in soft handoff in a wireless communication system, the mobile station receives a first sequence from a first base station, wherein the first sequence is formed by interleaving the transmitted data using the first interleaver module template, receives the second sequence from the second base station, while the second sequence is formed in the middle Twomey interleaving transmission data using a second template interleaving module, and combines the first sequence and a second sequence, and decodes the combined sequence before receiving the entire frame having a first sequence allocated to it.

In order to achieve the objective of the present invention, according to another aspect of the present invention, a mobile station receiving data in soft handoff in a wireless communication system includes a receiving module receiving a first sequence from a first base station, the first sequence being formed by interleaving the transmitted data using the first an interleaver module template, and receiving a second sequence from a second base station, the second sequence being s generated by interleaving the transmitted data using a second interleaving pattern module and the decoder combining the first sequence and a second sequence, and decoding the combined sequence before receiving the entire frame having a first sequence allocated to it.

Here, the second sequence may correspond to the first sequence cyclically shifted by (length of the first sequence / 2).

In addition, the mobile station may transmit the ACK to the base station when decoding is successfully performed.

In addition, the first sequence and the second sequence can be encoded as convolutional codes.

In addition, the transmitted data may correspond to voice data.

In order to achieve the objective of the present invention, according to another aspect of the present invention, in a method for transmitting data from a first base station communicating with a mobile station in soft handoff in a wireless communication system, the first base station transmits a first sequence to the mobile station, wherein the first sequence is generated by interleaving the transmitted data using the first template of the interleaver, and stops transmitting the frame having the first sequence st allocated to it when a positive acknowledgment (ACK) is received from the mobile station. Herein, the first sequence is different from the second sequence generated from the second base station by interleaving the transmitted data using the second template of the interleaving module, the second base station communicating with the mobile station.

In order to achieve the objective of the present invention, according to an additional aspect of the present invention, in a base station communicating with a mobile station in soft handoff in a wireless communication system, the base station includes an encoder encoding the transmitted data and an interleaver forming the first sequence by interleaving the coded data using the first interleaver module template. Herein, the first base station stops transmitting a frame having a first sequence allocated to it when a positive acknowledgment (ACK) is received from the mobile station, and the first sequence is different from the second sequence generated from the second base station by interleaving the transmitted data using the second pattern an interleaver, the second base station communicating with the mobile station.

Here, the second sequence may correspond to the first sequence cyclically shifted by (length of the first sequence / 2).

In addition, the mobile station may transmit the ACK to the base station when decoding is successfully performed.

In addition, the first sequence and the second sequence can be encoded as convolutional codes.

In addition, the transmitted data may correspond to voice data.

Advantages of the Invention

According to embodiments of the present invention, each of several base stations communicating with a mobile station surrounded by soft handoff uses a different pattern or code in order to transmit data. Thus, the gain from early termination in a handover environment may increase.

The advantages of the invention are not limited only by the advantages indicated in the description set forth herein, and other advantages can be realized and achieved by the structure specifically indicated in the detailed description and claims, as well as in the accompanying drawings.

Brief Description of the Drawings

Figure 1 illustrates a reverse link power control method in a CDMA2000 system.

Figure 2 illustrates an example application of a method for early termination in a reverse link traffic channel.

FIG. 3 illustrates an example frame transmission method for varying TPR according to an embodiment of the present invention.

4 illustrates a two-step reduction TPR method according to an embodiment of the present invention.

5 illustrates an exemplary multi-step variation TPR method according to an embodiment of the present invention.

6 illustrates a forward link power control method.

7 illustrates a forward link power control method according to an embodiment of the present invention.

FIG. 8 illustrates a method for controlling an external reverse link power control loop according to a first embodiment of the present invention.

FIG. 9 illustrates a method for controlling an external forward link power control loop according to a first embodiment of the present invention.

10 illustrates a method for controlling an external reverse link power control loop according to a second embodiment of the present invention.

11 illustrates a method for controlling an external forward link power control loop according to a second embodiment of the present invention.

12 illustrates a method for controlling an external reverse link power control loop according to a third embodiment of the present invention.

13 illustrates a method for controlling an external forward link power control loop according to a third embodiment of the present invention.

14 illustrates an example of an ACK retransmission according to an embodiment of the present invention.

15 illustrates an example of a NACK retransmission according to an embodiment of the present invention.

Fig. 16 (a) illustrates a method for designating a data rate in a forward link according to an embodiment of the present invention, and Fig. 16 (b) illustrates a method for designating a data rate in a reverse link according to an embodiment of the present invention.

FIG. 17 (a) illustrates a structure of a first base station according to a first embodiment of the present invention, and FIG. 17 (b) illustrates a structure of a second base station according to a first embodiment of the present invention.

Fig. 18 illustrates a structure of a mobile station according to a first embodiment of the present invention.

19 illustrates a method for transmitting and receiving data in soft handoff according to a second embodiment of the present invention.

Fig. 20 (a) illustrates the structure of a convolutional code encoder having a generating polynomial (561, 753), and the structure of a convolutional code encoder having a generating polynomial (557, 751), and Fig. 20 (b) illustrates the structure of an encoder having combined two convolutional code.

Figure 21 illustrates the upper limit of the bit error rate (BER) of each of the codes at a rate of 1/2 and the combined code at a rate of 1/4.

FIG. 22 illustrates a structure of a base station according to a third embodiment of the present invention.

23 illustrates an example transmission chain of a transmitting side using a wireless structure according to an embodiment of the present invention.

24 illustrates another example of a transmit side of a transmission chain using a wireless structure according to an embodiment of the present invention.

25 illustrates a communication process between two base stations using wireless structures and a mobile station in a handover mode according to an embodiment of the present invention.

FIG. 26 illustrates an example handover process using a wireless structure according to an embodiment of the present invention.

FIG. 27 illustrates another exemplary handover process using a wireless structure according to an embodiment of the present invention.

FIG. 28 illustrates an exemplary F-PCSCH and F-ACKSCH control channel structure when using a wireless structure according to an embodiment of the present invention.

29 illustrates another exemplary F-PCSCH and F-ACKSCH control channel structure using a wireless structure according to an embodiment of the present invention.

FIG. 30 illustrates yet another exemplary structure of an F-PCSCH and F-ACKSCH control channel using a wireless structure according to an embodiment of the present invention.

The optimal mode of carrying out the invention

The following is a detailed description of preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The accompanying drawings, which are included in order to provide an additional understanding of the invention, and which are contained and form part of this application, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. If possible, the same reference numbers are used in the drawings in order to refer to the same or similar elements. Also parts irrelevant to the description of the present invention are omitted.

Throughout the description of the present invention, when saying that a part “includes” an element (or part of an element), unless otherwise indicated, this does not mean that other elements are excluded, but means that other elements can be further included. In addition, each of the terms referred to as “--- module”, “-er (or -or)”, “module”, etc., indicates a module that processes at least one function or operation, and can be implemented in hardware or software forms or a combination of hardware and software.

When the early termination method is applied to the circuit channels, embodiments of the present invention describe methods that can increase the gain from the early termination method.

First, a method for transmitting a frame when changing (or varying) the traffic pilot signals (hereinafter referred to as TPR) according to an embodiment of the present invention is described in detail below.

TPR is referred to as the relationship between the power allocated to the traffic channel and the power allocated to the pilot channel. More specifically, in order to provide the required traffic channel performance, the power allocated to the traffic channel is maintained at a constant ratio with respect to the power allocated to the pilot channel. Throughout this document, TPR indicates a power allocation relationship between a traffic channel and a pilot channel.

TPR varies depending on the transmission rate, coding method and the period of the transmission frame of the traffic channel. For example, in a CDMA2000 system, when a speech signal (or audio signal) is transmitted via a reverse main channel (R-FCH) at 9600 bits per second, the TPR becomes 3.75 dB. More specifically, compared with the transmit power of the pilot channel, the transmit power of the traffic channel is 3.75 dB higher.

In the prior art method, except when the TPR needs to change due to a change in the channel environment, the TPR is kept constant. In the event that the TPR is to change due to a change in the channel environment, the base station again selects the appropriate value and notifies the new TPR value to the mobile station. In other words, a fixed value is used within a single frame.

A frame transmission method according to an embodiment of the present invention transmits a traffic signal to each time slot by applying a TPR optimized for each time slot within the frame, depending on the state of the channel and system.

FIG. 3 illustrates an example frame transmission method for varying TPR according to an embodiment of the present invention.

As shown in FIG. 3, the advantages of the early termination method can take effect when the start of the frame transmits the traffic channel at high TPR and when the end of the frame transmits the traffic channel at low TPR. If the early termination method is applied to the circuit channel, the signals of at least 2 or more time quanta are unnecessarily transmitted from the beginning at the point at which the receiving side successfully decodes the data to the point at which the transmitting side stops transmitting the signals of the corresponding frame . Therefore, by setting the final part of the frame in which the probability of feedback on the ACK becomes greater, so as to have a low TPR, the amount of power of excessively transmitted signals can be reduced, thereby reducing the level (or magnitude) of interference of the entire system.

In a method for transmitting a frame by varying the TPR according to an embodiment of the present invention, the base station can change the TPR by using a variety of methods.

Firstly, according to the TPR method with a step-by-step reduction of TPR within one frame, it has two different values, while the first to N-th time quanta use a higher TPR value, and at the same time, the (N + 1) -th time quanta the latter use a lower TPR value.

According to the method of the prior art, when the transmission speed of the data is 9600 bits per second, all 16 time slices within the general channel environment use a TPR of 3.75 dB. In this document, according to the step-by-step TPR method, the first 8 time slices can use 5.5 dB TPR, which corresponds to TPR 1.5 times (1.75 dB) higher than the traditional TPR, and the remaining 8 time slices can use 0.75 dB TPR, which corresponds to TPR 50% lower than traditional TPR.

Then, according to the TPR method with multi-step decreasing, TPR within one frame has three different values, wherein the time quanta of one frame are divided into several regions, while the temporal quanta belonging to the first region use the highest TPR value, while the temporal quanta belonging to the following areas, respectively, use TPR values that are successively lower than the first (or highest) TPR.

4 illustrates a two-step reduction TPR method according to an embodiment of the present invention.

Referring to FIG. 4, according to the TPR method with a two-step reduction of TPR within one frame has three different values, while the time slices of one frame are divided into 3 different areas. In this document, time slices belonging to the first region use the highest TPR value, time slices belonging to the second region use the second highest TPR value, and time slices belonging to the third region use the lowest TPR value.

Then, according to the TPR method with multi-step variation, the TPR within one frame has several values, wherein the time quanta of one frame are divided into several regions, and the time quanta belonging to the first region use the first TPR value, and the temporal quanta belonging to the following areas, respectively, use the following TPR values.

5 illustrates an exemplary multi-step variation TPR method according to an embodiment of the present invention.

Referring to FIG. 5, time slices in one frame are divided into 8 regions, and each region includes 2 PCGs. Time slices in each region use TPR values appropriate for each group, respectively. 5, a higher TPR value is used at the beginning of the frame, and lower TPR values are used with respect to increasing the PCG index. Then the TPR values again become higher almost at the end of the frame. This is necessary in order to increase the likelihood of early termination by using higher TPR values at the beginning of the frame, as well as to increase the success rate of frames by using again higher TPR values at the end of the frame. The multi-step variation TPR method can be extended to an independent TPR allocation method for all PCGs.

The base station and the mobile station know a predetermined default TPR value and use this default value. However, in the event that the TPR value is to be changed in accordance with the channel environment (or conditions) of the mobile station, the base station uses top-level signaling in order to report such a request to the mobile station. However, according to the TPR method with multi-step variation, since the TPR value is set for each area, if the TPR value for each area is to be reported to the mobile station via the transmission of upper level signaling, the amount of overhead information becomes too large. Therefore, an embodiment of the present invention provides a method in which the mobile station and the base station know a predetermined set of TPR boost values and in which the base station reports a corrected TPR _MOD value and a TPR boost set of index values.

Table 1 shows examples of sets of TPR boost values according to an embodiment of the present invention.

Table 1 TPR Boost Value Set Index TPR_boost PCG
0.1 PCG 2,3 PCG 4.5 PCG 6.7 PCG 8.9 PCG 10.11 PCG 12.13 PCG 14.15 0 one one one one one one one one one 1,5 1,5 1,5 1,5 0.5 0.5 0.5 0.5 2 1,5 1,5 0.5 0.5 0.5 0.5 1,5 1,5 3 1,5 1.25 0.75 0.5 0.5 0.75 1.25 1,5

As shown in Table 1, if the set of TPR boost values between the mobile station and the base station is determined when the base station notifies the adjusted TPR _MOD value and the index of the set of TPR boost values, the mobile station can calculate the TPR (i) of the ith PCG by equation 1 below.

TPR (i) = TPR_boost (i) * TPR _MOD Equation 1

In this document, TPR_boost (i) represents the TPR_boost value of the i-th PCG shown in Table 1.

The following describes in detail a method for transmitting a frame by varying the relationship between the transmit power of the direct power control subchannel and the transmit power of the forward traffic channel (or the F-TCH to F-PCSCH ratio, hereinafter referred to as the “F-TCH / F-PCSCH power ratio”) in the forward communication lines according to an embodiment of the present invention.

Since the forward link pilot channel is a common channel, the pilot channel cannot be subjected to power control. Therefore, forward link power control must be performed by directly controlling the receive power of the forward traffic channel (hereinafter referred to as F-TCH). In this document, when the forward traffic channel provides a variable data rate service, such as a voice (or audio) service, due to the uncertainty of the transmission rate, the receiving side cannot directly measure the reception power of the traffic channel.

6 illustrates a forward link power control method.

As shown in FIG. 6, the base station transmits a direct power control subchannel (hereinafter referred to as F-PCSCH), which is a PCB feedback channel for controlling transmit power in the reverse link, to the mobile station via the forward link along with the traffic channel . Since the F-PCSCH has a fixed data rate, the F-PCSCH can be directly used to measure the reception power. The transmit power of the F-TCH is set by the power ratio of the F-TCH / F-PCSCH, and according to the prior art, the power ratio of the F-TCH / F-PCSCH is maintained within one frame. The mobile station measures the receive power of the F-PCSCH in order to use the previously known power ratio F-TCH / F-PCSCH, thereby calculating the energy-to-noise ratio (Eb / No) per one received bit when the data rate F -TCH is 9600 bits per second. After that, the mobile station compares the Eb / No with a predetermined value to generate a power control bit (hereinafter referred to as a PCB), thereby transmitting the generated PCB to the base station via a reverse power control subchannel (hereinafter referred to as R-PCSCH) and controlling the transmit power F -TCH and F-PCSCH.

7 illustrates a forward link power control method according to an embodiment of the present invention.

According to an embodiment of the present invention, the power ratio of the F-TCH / F-PCSCH varies within a single frame. For example, as shown in FIG. 7, when the data rate is 9600 bits per second and when the reference value is 0 dB, the one-step reduction method is applied so that the first 8 time slices can use the F-TCH / F-PCSCH power ratio of 1 , 75 dB, which corresponds to a power ratio of F-TCH / F-PCSCH 1.5 times the reference ratio, and so that the remaining 8 time quanta can use a power ratio of F-TCH / F-PCSCH of -3 dB, which corresponds to the power ratio F-TCH / F-PCSCH 50% below the reference ratio, thereby fulfilling ny transfer.

Accordingly, the mobile station measures the receive power of the F-PCSCH and compares the receive Eb / No of the FL-PCB with the set value to form the reverse link PCB (RL-PCB) and transmit the generated RL-PCB to the base station, thereby performing power control in direct line of communication.

In addition, the base station divides the time slices within one frame into several regions and can inform the mobile station in advance of the F-TCH / F-PCSCH power ratio for each region. Accordingly, the mobile station can measure the receiving power of the F-PCSCH in each region in order to use the previously known power ratio F-TCH / F-PCSCH of the corresponding region, thereby calculating the energy-to-noise ratio (Eb / No) per one the received bit when the F-TCH data rate is 9600 bits per second. After that, the mobile station can compare the Eb / No with a predetermined value to form a PCB.

The following describes in detail a method for controlling an external power control loop according to an embodiment of the present invention.

In general, power control is performed through an internal power control loop and an external power control loop.

The internal power control loop measures the energy of the received signal at the receiving side. Then, when the energy of the received signal exceeds a predetermined predetermined value, the power down control command is transmitted to the transmitting side. Also, when the energy of the received signal is lower than a predetermined predetermined value, the power control up command is transmitted to the transmitting side. Thus, power control is performed. External power control corresponds to a setpoint control that is used in the internal power control loop so that the target frame error rate (target FER) can be satisfied.

According to a general method for controlling an external power control loop, in case the target FER is F, the receiving side increases the setpoint by x dB when a frame error occurs. Then, when the frame is successfully decoded, the receiving side decreases the set value by x / (1-1 / F) dB. For example, if the target FER is 1%, the receiving side increases the setpoint by 1 dB when a frame error occurs. Then, when the frame is successfully decoded, the receiving side reduces the set value by 1 / (1-1 / 0,01) dB = 1/99 dB.

Here, if the x value x dB, which corresponds to the increased value of the set value, is set to have a high value, and when the set value required by the change in the channel environment varies, it is advantageous that the receiving mobile station can quickly vary set value. However, in a channel environment that is not subject to change and has a stable setpoint, the setpoint used may become unstable (or may tremble) around the desired setpoint, thereby leading to a critical problem. In addition, the setpoint that is used when frame errors occur sequentially due to instantaneous impulse noise is set to exceed the desired setpoint. Therefore, a long period of time can pass so that the setpoint used is rolled back to the desired setpoint.

Therefore, in order to solve such problems when the early termination method is applied to the circuit channel, an embodiment of the present invention provides a method for controlling an external power control loop.

First, a method for controlling an external power control loop according to a first embodiment of the present invention is described in detail with reference to FIG. 8 and FIG. 9.

According to the early termination method, the receiving side attempts to decode in a state in which part of the frame is received. In an embodiment of the present invention, from the plurality of attempt points for decoding, at least one or more target decoding attempt points are set, thereby defining a target FER of the target decoding attempt point so that the target decoding attempt points satisfy the target FER at, in which the whole frame is accepted. Then, the predetermined value of the inner power control loop is controlled so that the target FER at a certain point in the attempt for target decoding can be satisfied.

For example, when the target FER at the point at which the entire frame is received corresponds to 1%, the target FER at the point of attempt for the target decoding may be set to 20-50%. In addition, the set value of the internal power control loop can be controlled so that the target FER at the point of attempt for target decoding can be satisfied.

Fig. 8 illustrates a method for controlling an external reverse link power control loop according to a first embodiment of the present invention, and Fig. 9 illustrates a method for controlling an external forward link power control loop according to a first embodiment of the present invention.

Referring to FIG. 8, the base station controls the target FER of the target decoding attempt point so that an end FER that corresponds to the target FER of the point at which the entire frame is received can be satisfied. In addition, the base station controls the set value so that the target FER of the target decoding attempt point can be satisfied. In addition, when the base station receives a signal from the mobile station, the base station compares the energy of the received signal with a predetermined value to generate a power control command, thereby transmitting the generated command to the mobile station.

Referring to FIG. 9, a mobile station controls a target FER of a target decoding attempt point so that an end FER that corresponds to a target FER of a point at which the entire frame is received can be satisfied. In addition, the mobile station controls the set value so that the target FER of the target decoding attempt point can be satisfied. In addition, when the mobile station receives a signal from the base station, the mobile station compares the energy of the received signal with a predetermined value to generate a power control command, thereby transmitting the generated command to the base station.

Next, a method for controlling an external power control loop according to a second embodiment of the present invention is described in detail with reference to FIG. 10 and FIG. 11.

According to a second embodiment of the present invention, when the receiving side transmits the target FER of the point receiving the whole frame to the transmitting side, the transmitting side sets the target FER of the point of the target decoding attempt so that the target FER of the point receiving the whole frame can be satisfied. Then, when the transmitting side transmits the predetermined target FER to the receiving side, the receiving side controls the set value of the internal power control loop so that the received target FER can be satisfied.

When the data rate is variable, for example, for audio (or speech) data, there is a zero data rate. More specifically, in some cases, data is not actually transmitted for the frame when the decoding of the frame is unsuccessful, it is difficult for the receiver to identify whether the decoding of the file is unsuccessful due to a channel error or the decoding of the file is unsuccessful because there is no transmitted data.

Therefore, in the second embodiment of the present invention, if the receiving side notifies the number of successfully decoded frames during a predetermined period of time to the transmitting side, the transmitting side sets the target FER of the target decoding attempt point so that the target FER of the point receiving the entire frame can be satisfied, taking into account the measurement duration for the number of successfully decoded frames, the number of successfully decoded frames and the number of frames without data transmission, thereby notifying the receiving side of given target FER.

FIG. 10 illustrates a method for controlling an external reverse link power control loop according to a second embodiment of the present invention, and FIG. 11 illustrates a method for controlling an external forward link power control loop according to a second embodiment of the present invention.

Referring to FIG. 10, the base station transmits the final FER, which corresponds to the target FER of the point at which the entire frame is received, and the number of successfully decoded frames for a given time period. Accordingly, the mobile station sets the target FER of the target decoding attempt point so that the target FER of the point receiving the entire frame can be satisfied, taking into account the duration of the measurement for the number of successfully decoded frames, the number of successfully decoded frames and the number of frames without data transmission, thereby notifying the base station of the specified target FER. In addition, the base station controls the setpoint of the internal power control loop so that the received target FER can be satisfied. In addition, when the base station receives a signal from the mobile station, the base station compares the energy of the received signal with a predetermined value to generate a power control command, thereby transmitting the generated command to the mobile station.

Referring to FIG. 11, the mobile station transmits the final FER, which corresponds to the target FER of the point at which the entire frame is received, and the number of successfully decoded frames for a given time period. Accordingly, the base station sets the target FER of the target decoding attempt point so that the target FER of the point receiving the entire frame can be satisfied, taking into account the duration of the measurement for the number of successfully decoded frames, the number of successfully decoded frames and the number of frames without data transmission, thereby notifying the mobile station of the specified target FER. In addition, the mobile station controls the set value of the internal power control loop so that the received target FER can be satisfied. In addition, when the mobile station receives a signal from the base station, the mobile station compares the energy of the received signal with a predetermined value to generate a power control command, thereby transmitting the generated command to the base station.

Hereinafter, a method for controlling an external power control loop according to a third embodiment of the present invention is described in detail with reference to FIG. 12 and FIG. 13.

According to a third embodiment of the present invention, when the receiving side transmits the target FER of the point receiving the whole frame to the transmitting side, the transmitting side compensates the transmitted signal so that the target FER of the point receiving the whole frame can be satisfied.

12 illustrates a method for controlling an external reverse link power control loop according to a third embodiment of the present invention, and FIG. 13 illustrates a method for controlling an external forward link power control loop according to a third embodiment of the present invention.

Referring to FIG. 12, the base station transmits the target FER of the point receiving the entire frame to the mobile station. Accordingly, the mobile station calculates the target FER of the target decoding attempt point so that the target FER of the point receiving the entire frame can be satisfied. The mobile station then calculates the FER of the target decoding attempt point by using the ACK / NACK received from the base station. In addition, the mobile station compares the FER of the target decoding attempt point calculated by using ACK / NACK with the target FER, thereby compensating for the TPR of the transmitted signal.

Here, the base station uses a predetermined value of the internal power control loop.

Referring to FIG. 13, the mobile station transmits the target FER of the point receiving the entire frame to the base station. Accordingly, the base station calculates the target FER of the target decoding attempt point so that the target FER of the point receiving the entire frame can be satisfied. The base station then calculates the FER of the target decoding attempt point by using the ACK / NACK received from the mobile station. In addition, the mobile station compares the FER of the target decoding attempt point calculated by using ACK / NACK with the target FER, thereby compensating for the TPR of the transmitted signal. In this document, TPR refers to the power ratio of F-TCH / F-PCSCH.

Here, the mobile station uses a predetermined value of the internal power control loop.

The following describes in detail a method for transmitting acknowledgment / rejection (hereinafter referred to as ACK / NACK) according to an embodiment of the present invention.

When applying the early termination method to the circuit channel, the performance of the acknowledgment channel (hereinafter referred to as ACKCH) is important. Acceptance errors include an ACK2NACK error in which an ACK is recognized as NACK, and a NACK2ACK error in which a NACK is recognized as ACK. When an ACK2NACK error occurs, the transmitting side cannot prematurely complete the transmission of the corresponding frame, and therefore, early termination gain cannot be obtained. When a NACK2ACK error occurs, even if the corresponding frame is not decoded successfully by the receiving side, the transmitting side performs early completion to transmit the corresponding frame, thereby increasing the FER.

Therefore, in order to solve the above problem, according to an embodiment of the present invention, the mobile station transmits ACK / NACK repeatedly until the corresponding frame is completed.

14 illustrates an example of an ACK retransmission according to an embodiment of the present invention. Also, FIG. 15 illustrates an example of a NACK retransmission according to an embodiment of the present invention.

14 and 15 respectively illustrate ACK / NACK transmission in forward link traffic. However, the present invention can also be applied to ACK / NACK transmission in reverse link traffic.

As shown in FIG. 14, when the mobile station performs decoding at the decoding attempt point and successfully performs the decoding process, the mobile station continuously transmits an ACK signal to the base station until the corresponding frame is completed. Therefore, even when an ACK2NACK error occurs, if the base station receives the next transmitted ACK signal without errors, frame transmission may end early.

As shown in FIG. 15, when a NACK2ACK error occurs, the base station receives the ACK and stops transmitting the frame. Then, when the next transmitted NACK signal is received without errors, the base station continues to transmit the frame.

Hereinafter, a method for designating a data rate according to an embodiment of the present invention is described in detail.

When the early termination method is applied to the circuit channel, the receiving side performs decoding at each point of the decoding attempt. Therefore, the complexity of the receiver is increased compared to the case when they try to perform decoding only once at the end of the frame. In particular, if the data rate of the traffic channel corresponds to a variable speed, blind decoding should be performed by assuming all speeds as part of a set of variable speeds at all points of the decoding attempt.

In order to enhance the effect of the early termination method, since decoding must be completed within a short period of time, and since ACK feedback must be sent to the transmitting side in order to stop (or interrupt) further unnecessary transmission, the receiver must quickly perform decoding. However, in order to perform decoding for a short period of time by assuming all speeds within a set of variable speeds, the complexity of the receiver ultimately increases.

Therefore, an embodiment of the present invention provides a method for designating a data rate or a subset of frame data rates for a receiving side.

Fig. 16 (a) illustrates a method for designating a data rate in a forward link according to an embodiment of the present invention, and Fig. 16 (b) illustrates a method for designating a data rate in a reverse link according to an embodiment of the present invention.

Using ACKSCH at the beginning of a frame is very unlikely. Therefore, as shown in FIGS. 16 (a) and (b), at the beginning of the frame, the ACKSCH source can be used to indicate the data rate. More specifically, an ACKSCH source can be used as a subchannel of a speed indicator (hereinafter referred to as RISCH) at the beginning of a frame. According to an embodiment of the present invention, an identical wireless source or an identical source of CDMA codes is used as a RISCH at the beginning of a frame, and this source is used as an ACKSCH at the end of a frame.

When transmitting speech (or audio) signal data, for example, in a CDMA2000 system, traffic channel data rates may consist of 5 variable data rates: 9600 bits per second, 4800 bits per second, 2400 bits per second, 1200 bits per second and 0 bits per second. In this case, the data rate may be indicated as shown in Table 2. Table 2 shows an example of modulation symbols transmitted through the RISCH for each data rate. More specifically, the transmitting side transmits a symbol corresponding to the data rate shown in Table 2 to the receiving side so that the receiving system can report the frame data rate.

table 2 Data rate Modulation Symbol in RISCH 9600 bits per second one 4800 bits per second -one 2400 bits per second J 1200 bits per second -j 0 bits per second 0

In addition, the transmitting side can modulate the RISCH, as shown in table 3 or table 4. Table 3 shows another example of modulation symbols transmitted through the RISCH for each data rate. Table 4 also shows another other example of modulation symbols transmitted through RISCH for each data rate.

Table 3 Data rate Modulation Symbol in RISCH 9600 bits per second one 4800 bits per second, or 2400 bits per second, or 1200 bits per second -one 0 bits per second 0

Table 4 Data rate Modulation Symbol in RISCH 4800 bits per second one 2400 bits per second or 1200 bits per second -one 0 bits per second or 9600 bits per second 0

As shown in table 3 or table 4, when several data rates are modulated into one symbol, even when an error occurs in the RISCH during the transmission process, the probability of the correct modulation of the signal at the receiving side is high. Because the receiver can decode the highest data rate, the receiver can simultaneously perform blind decoding at several low data rates.

In the case of a voice service, Table 4 highlights the modulation symbol 0 for 9600 bits per second and 0 bits per second, which have the highest occurrence rate, thereby having the advantage of reducing the amount of RISCH transmission power overhead.

When the transmitting side transmits the modulation symbol to the receiving side, as shown in tables 1-3, through RISCH, the receiving side assumes a data rate corresponding to the modulation symbol, thereby decoding the decoding attempt point. In addition, when decoding is not successful at the decoding attempt point, the receiving side performs blind decoding for all sets of data rates after receiving the entire frame.

If an error occurs in RISCH, since the RISCH is transmitted at the beginning of the frame, the start of the frame disappears. However, if the beginning of the frame disappears, the likelihood of early termination of the frame is reduced. Therefore, there is virtually no degradation in the performance of the traffic channel caused by an error in the RISCH.

Hereinafter, a method for controlling standby power using negative NACK according to an embodiment of the present invention is described in detail.

When the early termination method is applied to the circuit channel, the ACKSCH transmits the modulation symbol 1 as ACK and the modulation symbol 0 as NACK in order to reduce the transmission power overhead. More specifically, in the case of NACK, since the signal power transmitted in the ACKSCH is 0, the amount of overhead information of the ACKSCH transmission power may be reduced.

An embodiment of the present invention provides a method for transmitting a negative NACK. According to an embodiment of the present invention, the modulation symbol 1 is transmitted as ACK, the modulation symbol 0 is transmitted as NACK, and the modulation symbol -1 is transmitted as negative NACK.

A negative NACK may be used to perform backup power control.

For example, the receiving side measures the reception energy of the traffic channel at the decoding attempt point. Then, when the receiving side determines that the reception energy of the frame does not satisfy the energy required to successfully receive the frame at the end point of the frame, the receiving side transmits a negative NACK to the transmitting side so that the transmitting side can increase the transmit power of the traffic channel.

In another example, when the energy of the signal received by the receiving side is lower than the predetermined power control value by a predetermined level or more, the receiving side transmits the negative NACK to the transmitting side and the transmitting side receiving the negative NACK increases the transmit power by PC_UP_SIZE + B00ST_UP [dB] .

More specifically, when the reception energy (Rx_Pwr) of the reference power control channel is lower than the predetermined power control value by a predetermined level (Boost_Th) or more (Rx_Pwr <(preset value-Boost_Th)), the receiving side transmits a negative NACK to the transmitting side. Here, since the reception energy falls below a predetermined value (Rx_Pwr <predetermined value) during the general power control process, the uplink power control command is transmitted to the transmitting side. In general, when the transmitting side receives an increase power control command, the transmit power is increased by PC_UP_SIZE. Alternatively, when the transmitting side receives both the uplink power control command and the negative NACK, the transmit power is increased by PC_UP_SIZE + BOOST_UP [dB].

In addition, if the feedback channel on the ACK / NACK is more reliable than the feedback channel on the PCB, when the transmitting side receives a negative NACK, the transmitting side ignores the received power control command and can increase the transmit power by PC_UP_SIZE + BOOST_UP [dB] .

In addition, in the event that the mobile station receives a power control command from two base stations in a handover condition (or situation), thereby performing reverse link channel power control, according to an embodiment of the present invention, when the mobile station receives a negative NACK from both base stations within a specific time window, the mobile station can increase the transmit power by PC_UP_SIZE + BOOST_UP [dB].

Hereinafter, a method for transmitting and receiving data in soft handoff according to an embodiment of the present invention is described in detail.

In the prior art method, in soft handoff, a mobile station receives identical information from several base stations. Therefore, the mobile station cannot maximize the benefits of early termination. Therefore, this embodiment of the present invention provides a method for transmitting and receiving data that can increase early termination gain surrounded by a handover by instructing several base stations that communicate with the mobile station to transmit data using a different pattern or code.

The process of obtaining high coding efficiency by instructing several base stations that communicate with the mobile station environment soft handoff, transmit data using a different pattern or code and by instructing the mobile station to combine each of the different patterns or codes is referred to as soft handoff with combining (or association) by code.

First, a method for transmitting and receiving data in a soft handoff according to a first embodiment of the present invention is described in detail.

According to the first embodiment, when several base stations communicating with a mobile station in soft handoff respectively transmit a traffic channel carrying identical information, several base stations vary the corresponding transmission order of channel-coded coding bits, thereby increasing the gain from the early termination method . Hereinafter, an example 2 of base stations in contact with a mobile station in soft handoff is described with reference to FIG. 17 and FIG. 18.

FIG. 17 (a) illustrates a structure of a first base station according to a first embodiment of the present invention, and FIG. 17 (b) illustrates a structure of a second base station according to a first embodiment of the present invention.

As shown in FIGS. 17 (a) and (b), the base station according to the first embodiment of the present invention includes a cyclic redundancy check bit (hereinafter referred to as CRC) and tail bits adding module 171, an encoder 172, a rate matching module 173 , an interleaver 174 including a cyclic shift module, and a spread spectrum coding module and a modulator 175.

When a sequence of information bits is input, the tail and CRC add module 171 adds CRC bits and tail bits to the sequence of information bits. Encoder 172 FEC encodes a sequence of information bits.

The rate matching unit 173 performs rate matching, which matches the encoded sequence of information bits with the transmitted channel bits. More specifically, rate matching is the process of negotiating the amount of data that must be transmitted during each transmission time interval (TTI) at the maximum transmission amount of the actual channel.

The interleaver 174 cyclically shifts the traditional interleaving, which rearranges the sequence of information bits by means of specific regions and interleaves the sequences. A spread-spectrum coding module and a modulator 175 spread-spectrum encodes and modulates a cyclically shifted sequence. The modulated sequence is transmitted through a transmit antenna.

The interleaver 174 shifts the sequence by a predetermined cyclic shift value. According to a first embodiment of the present invention, the cyclic shift value of the first base station is different from the cyclic shift value of the second base station. If the sequence output from the interleaver is b ₀ , b ₁ , ..., b _N-1 , when the cyclic shift value of the cyclic shift module is a, the bit sequence output from the cyclic shift module becomes b _a , b _{a + 1} , ..., b _N-1 , b ₀ , b ₁ , ..., b _a-1 . Here, N represents the length of the sequence deduced from the interleaver.

For example, in the CDMA2000 system, when a mobile station in handover mode communicates with two base stations and when two base stations perform FEC channel coding of information bits to be transmitted in a forward link at a coding rate of ½, and when the value of cyclic the shift of the cyclic shift module of the first base station is 0, and when the cyclic shift value of the cyclic shift module of the second base station is N / 2, the bit sequence output from the nth shift of the first base station is b ₀ , b ₁ , ..., b _N-1 , and the bit sequence output from the cyclic shift module of the second base station is b _{N / 2} , b _{N / 2 + 1} , ..., b _{N / 2-1} . Therefore, the first base station transmits data in the order of b ₀ , b ₁ , ..., b _N-1 , and the second base station transmits data in the order of b _{N / 2} , b _{N / 2 + 1} , ..., b _{N / 2-1} . Accordingly, when the mobile station in the handover mode receives 1/2 frames in 20 ms, the first base station receives the entire sequence (b ₀ , b ₁ , ..., b _N-1 ). Therefore, when only 1/2 frame in 20 ms is received, the receiving coding rate becomes 1/2, thereby increasing the possibility of a successful decoding process at the receiving point of 1/2 frame in 20 ms. In addition, the possibility of a successful decoding process may increase when more than 1/4 and less than 1/2 frame in 20 ms is received.

In addition, in the forward link, when the base station performs FEC channel coding of information bits to be transmitted at a coding rate of 1/2, one information bit is modified into two parity bits. After that, the first parity sequence and the second parity sequence, interleaved by the interleaver, are sequentially transmitted. When the first embodiment of the present invention is applied to such a transmission method, the first base station transmits an interleaved first parity sequence to a mobile station in a handover mode and then transmits an interleaved second parity sequence. The second base station transmits an interleaved second parity sequence and then transmits an interleaved first parity sequence.

On the forward link, in order to send a power control command for power control in the reverse link, a portion of the coding bits of the traffic channel is punctured, and the F-PCSCH for sending the power control command is inserted. If the bit sequence transmitted by several base stations that communicate with the mobile station in the handover mode is not cyclically shifted, the traffic channel positions thinned by several base stations to transmit the F-PCSCH become identical to each other. Therefore, identical coding bits are punctured at each of several base stations. However, as shown in the first embodiment of the present invention, if several base stations cyclically shift the bit sequences to be transmitted by each of the corresponding cyclic shift values that are different from each other, the thinned positions in the traffic channel for transmitting F- PCSCHs become different at each of several base stations. Therefore, additional coding efficiency can be obtained.

As shown in FIG. 17, the interleaver 174 may include a cyclic shift module or interleaver, and the cyclic shift module may be implemented as a different element of the base station. If the interleaver 174 includes a cyclic shift module, each of several base stations communicating with the mobile station in a handover mode may use a different template of the interleaver to transmit the corresponding sequence in different commands.

For example, when 2 base stations communicate with a mobile station in a handover mode, the first base station can use the first interleaver module template, and the second base station can use the second interleaver module. Here, a sequence that is interleaved by using a second template of an interleaver corresponds to a cyclically shifted result of a sequence interleaved by using a first template of an interleaver.

When the length of the output sequence of the interleaver is N and when the sequence interleaved by using the second pattern cyclically shifts the sequence interleaved by using the first pattern by n / 2, if the sequence interleaved by using the first pattern is b ₀ , b ₁ , ... , b _N-1 , then the sequence interleaved by using the second pattern is b _{N / 2} , b _{N / 2 + 1} , ..., b _{N / 2-1} .

More specifically, when two base stations communicate with a mobile station in a handover mode, the cyclic shift value of the first base station may be 0, and the cyclic shift value of the second base station may be N / 2.

In addition, when more than two base stations communicate with the mobile station in a handover mode, the cyclic shift value of each base station may be 0 or N / 2.

Meanwhile, various cyclic shift values may be considered. For example, instead of multiples of 1/2, multiples of 1/4 can be defined as cyclic shift values. More specifically, when 2 or more base stations communicate with a mobile station in a handover mode, the cyclic shift value for each of these 4 base stations may be one of {0, N / 4, 2 * N / 4, 3 * N / four}.

If the base station that communicates with the mobile station in the handover mode changes when the base station transmits a handover direction message to the mobile station, the new added base station notifies the cyclic shift value that is being used and the new highlighted decoding attempt point.

Fig. 18 illustrates a structure of a mobile station according to a first embodiment of the present invention.

As shown in FIG. 18, a mobile station according to a first embodiment of the present invention includes a radio frequency and analog-to-digital converter (RF and AD converter) 181, a narrowing decoding module 182a, and a demodulator for a first base station (BS1), a deinterleaving module 183a for a first base station including a cyclic shift module for BS1, a narrowing decoding module and a demodulator 182b for a second base station (BS1), a deinterleaving module 183b for a second base station A station including a cyclic shift module for BS1, a combining module 184 combining information inversely interleaved by each base station, and a decoder buffer 185.

The RF and AD converter 181 converts the received analog signal into a digital signal. The narrowing decoding module and demodulator 182a for BS1 decodes the narrowing of the spectrum and demodulates the signal received from the first base station. Also, the deinterleaving module 183a for the first base station, including the cyclic shift module for BS1, cyclically shifts the signal received from the first base station, taking into account the cyclic shift value of the first base station. Thereafter, the deinterleaving unit 183a performs deinterleaving of the cyclically shifted received signal. Here, the cyclic shift module and the deinterleaving module 183a can respectively be implemented as separate elements of a mobile station.

In addition, the narrowing decoding module and demodulator 182b for BS2 decodes the narrowing of the spectrum and demodulates the signal received from the second base station. Also, the deinterleaving module 183b for the second base station, including the cyclic shift module for BS2, cyclically shifts the signal received from the second base station, taking into account the cyclic shift value of the second base station. Thereafter, the deinterleaving unit 183b performs deinterleaving of the cyclically shifted received signal. Here, the cyclic shift module and the deinterleaving module 183b can respectively be implemented as separate elements of a mobile station.

In addition, the reverse interleaved signal of the first base station and the reverse interleaved signal of the second base station are combined into a single signal by combining unit 184 and are thus stored in decoding buffer 185. Thus, the mobile station combines the reverse interleaved signal of the first base station and the reverse interleaved signal of the second base station, thereby decoding the combined signal. Prior to receiving the entire frame, when the mobile station attempts to decode the data during the reception of the frame and when the data reception is successful, the mobile station transmits the ACK to the base station via the reverse acknowledgment channel (ACK). Then, the base station receiving the ACK stops (or interrupts) the transmission of the corresponding frame. Here, the point at which the mobile station attempts to perform decoding (or the decoding attempt point of the mobile station) can be communicated to the mobile station via the base station. As shown in the first embodiment of the present invention, when the mobile station combines the signal of the first base station and the signal of the second base station and decodes the combined signal, the possibility of early termination may increase.

Hereinafter, a method for transmitting and receiving data in a soft handoff according to a second embodiment of the present invention is described in detail.

According to a second embodiment of the present invention, two or more base stations that communicate with a mobile station in soft handoff perform FEC channel coding of the data to be transmitted by using a convolutional code. In this document, each of two or more base stations uses a different generation polynomial convolutional code. Also, since the mobile station combines the signals received from two or more base stations and decodes the combined signal, the coding rate may become lower than the coding rate of one base station, thereby increasing the gain from the early termination method.

19 illustrates a method for transmitting and receiving data in soft handoff according to a second embodiment of the present invention.

Referring to FIG. 19, a mobile station in soft handoff communicates with two base stations, and the two base stations use a convolutional code having a 1/2 coding rate to perform FEC channel coding of the data to be transmitted. In this document, each first base station and the second base station use a different generating polynomial convolutional code. Accordingly, since the mobile station combines the signal received from each of the first base station and the second base station and decodes the combined signal, the coding rate becomes 1/4, and the probability of the successful decoding process when less than 1/2 of the frame is received can increase.

When the coding rate of the base station is 1/2 and when the frame length is 20 ms, since the mobile station, which is not surrounded by soft handoff, has a zero probability of a successful decoding process when only less than 1/2 of the frame is received, the decoding attempt point placed at more than 10 ms is allocated by the base station. However, when a mobile station that is not in a soft handoff area shifts to a soft handoff area to communicate with several base stations, a decoding attempt point located within 10 ms is additionally allocated to the mobile station.

In addition, if the base station that is communicating with the mobile station in the handover mode changes when the base station transmits a handover direction message to the mobile station, the new added base station notifies the cyclic shift value used by the base station and the new The highlighted decoding point. In addition, the decoding attempt points are predetermined based on the number of base stations communicating with the mobile station in the handover mode, and the mobile station may try to decode at predetermined decoding attempt points.

In this embodiment of the present invention, a method for generating a convolutional code to be used by two base stations when a mobile station is in handover mode communicates with 2 base stations is described.

Fig. 20 (a) illustrates the structure of a convolutional code encoder having a generating polynomial (561, 753) and the structure of a convolutional code encoder having a generating polynomial (557, 751). FIG. 20 (b) also illustrates the structure of an encoder having combined two convolutional codes.

Two convolutional codes, each of which has a different generating polynomial, respectively, form a different codeword, even when the input sequence is identical. However, as shown in FIG. 20 (b), two convolutional codes, each of which has a different generating polynomial, can be combined with a convolutional code having a low coding rate.

When it is assumed that each of the two base stations communicating with the mobile station in soft handoff uses a convolutional code having a 1/2 coding rate, since the mobile station combines each of the different codes respectively received from the two base stations, the coding rate becomes 1/4. Therefore, the generating polynomials used by the two base stations must be determined in such a way that combined convolutional codes having a coding rate of 1/4 demonstrate excellent performance.

In addition, since the mobile station communicates with one base station immediately before and after the handover process, the generating polynomials used by the two base stations must be determined in such a way that each of the two convolutional codes having a 1/2 coding rate demonstrates superior performance. More specifically, before initiating a handover process, the mobile station communicates with the serving base station. Also, after the handover process, since the mobile station exchanges data with the target base station, the performance of the convolutional codes at 1/2 speed used by each of the two base stations is no less important than the performance of the combined convolutional code having the encoding rate in 1/4.

Nevertheless, taking into account the fact that the coding efficiency at a coding rate of 1/4 significantly exceeds the coding efficiency at a coding rate of 1/2, the performance of a convolutional code with a rate of 1/2 used by each base station should first be considered .

Therefore, in the second embodiment of the present invention, the standard for creating convolutional codes to be used by two base stations consists, firstly, of demonstrating the excellent performance of convolutional codes at 1/2 speed used by each of the two base stations, and secondly, the preferred demonstration of high performance combined convolutional code having a coding rate of 1/4.

Table 5 shows the generating polynomials when the coding rate is 1/2 and when the length of the code constraint corresponds to K = 9.

Table 5 Designation Generating polynomial in octal format d (free distance) Johannesson 557, 751 12 Chambers 515, 677 12 3GPP2 561, 753 12

Of the generating polynomials shown in Table 5, the generating polynomial showing the most excellent performance is (561, 753). Therefore, the generating polynomial (561, 753) is selected. Also in what follows, this document analyzes an example of when a selected generating polynomial (561, 753) is combined with a generating polynomial (557, 751), and an example of when a selected generating polynomial (561, 753) is combined with a generating polynomial (515, 677).

Table 6 shows a combination of generating polynomials.

Table 6 Designation Generating polynomial in octal format The first code is 1/2 Second code 1/2 1/4 Combined Code 3GPP2 + Johannesson (561, 753) (557, 751) (561, 753, 557, 751) 3GPP2 + Chambers (561, 753) (515, 677) (561, 753, 515, 677)

Figure 21 illustrates the upper limit of the bit error rate (BER) of each of the codes at a rate of 1/2 and the combined code at a rate of 1/4.

Referring to FIG. 21, when the encoding rate is 1/4, the performance of 3GPP2 + Johannesson may be slightly degraded. However, it is obvious that when the encoding speed is 1/2, 3GPP2 + Johannesson shows the most excellent performance. When the encoding speed is 1/4, the performance of the 3GPP2 + Johannesson code at 1/4 does not show a significant difference from the 1/4 3GPP2 code, which demonstrates the most excellent performance. Therefore, according to the standard of the second embodiment of the present invention, the 3GPP2 + Johannesson code is selected.

Hereinafter, a method for transmitting and receiving data in a soft handoff according to a third embodiment of the present invention is described in detail.

According to a third embodiment of the present invention, when negotiating the data rate to be transmitted, each of several base stations that communicate with the mobile station in soft handoff uses a different rate matching pattern to provide additional coding rate and benefit from the early termination method .

FIG. 22 illustrates a structure of a base station according to a third embodiment of the present invention.

As shown in FIG. 22, a base station according to a third embodiment of the present invention includes an end bit and CRC module 221, an encoder 222, a rate matching module 223, an interleaver 224, and a spread coding module and modulator 225.

When a sequence of information bits is input, the tail and CRC add module 221 adds CRC bits and tail bits to the sequence of information bits. Encoder 222 FEC encodes a sequence of information bits.

The rate matching unit 223 performs rate matching, which matches the encoded sequence of information bits with the transmitted channel bits. More specifically, rate matching is the process of negotiating the amount of data that must be transmitted during each transmission time interval (TTI) at the maximum transmission amount of the actual channel. Here, each of several base stations communicating with a mobile station in a handover mode uses a different rate matching pattern. Accordingly, the sequences transmitted by each of several base stations become different from each other.

The interleaver 224 cyclically shifts the conventional interleaving, which rearranges the sequence of information bits by means of specific regions and interleaves the sequences. A spread-spectrum coding module and a modulator 225 spread-spectrum encodes and modulates a cyclically shifted sequence. The modulated sequence is transmitted through a transmitting antenna by passing through an RF cascade.

Hereinafter, a radio configuration according to an embodiment of the present invention is described.

When the above methods for increasing the throughput for voice (or audio) are applied to the wireless communication system, the maximum number of users that can be adapted by the wireless communication system can be increased. However, since the traffic channel is identified by the Walsh code in the forward link of the CDMA system, the number of traffic channels that can be supported by the CDMA system is limited by the number of Walsh codes. On the CDMA2000 system’s forward link, since each channel of voice (or audio) traffic is specified by a Walsh code having a length of 128, if the code is not expanded by using a quasi-orthogonal code, the maximum number of supported channels of voice (or audio) traffic on the forward link at 1.25 MHz cannot exceed 128.

When the mobile station is in the handover area, since a traffic channel is allocated from several base stations, Walsh code support for each of several base stations is used. More specifically, when the mobile station is in an N-way handoff area having N sectors defined as active sectors, a Walsh code of length 128 is allocated from each of the N sectors.

When all mobile stations are in an area without a handoff, the maximum number of 128 users can adapt in the 1.25 MHz frequency band per sector. However, when all mobile stations are in the area of two-way handover, the number of users actually adapting in the 1.25 MHz band per sector is reduced to 64 users. More specifically, as the number of mobile stations in the handover area increases, and as the number of active sectors in the handover areas increases, the maximum number of users that can actually be adapted for each sector decreases.

In this embodiment of the present invention, in order to rationalize (or maintain) the Walsh code support that is unnecessarily required during the handover process, the Walsh code is time-divided to form the base channel, thereby performing channel allocation by means of the respective modules. Therefore, the conventional circuit channel is defined by the Walsh code index according to the length of the Walsh code. However, according to an embodiment of the present invention, the base channel is defined by the Walsh code index according to the length and time index of the Walsh code.

For example, when one base channel is specified by the PCG with an even Walsh code index number and when another base channel is specified by the PCG with an odd number, two base channels can be specified by using only one Walsh code.

In another example, when one base channel is specified by the first 10 ms of a 20 ms frame of one Walsh code index and when another base channel is specified by the next 10 ms of this frame of 20 ms, two base channels can be specified by using only one Walsh code .

In addition, one Walsh code may be split in time to share 3 or more base channels.

When one Walsh code is split in time to specify a plurality of base channels, each of the base channels may have a transmission coding rate of 1 or higher. In this case, in order to enable the receiving side to successfully receive data, the transmitting side transmits the same data to the plurality of base channels so that the combined coding rate of the receiving side becomes less than 1.

23 illustrates an example transmission chain of a transmitting side using a wireless structure according to an embodiment of the present invention.

As shown in FIG. 23, in a transmission chain of a transmitting side using a wireless structure according to an embodiment of the present invention, the traffic channel consists of two base channels, i.e. direct primary traffic channel (hereinafter referred to as F-PTCH) and direct additional traffic channel (hereinafter referred to as F-STCH).

23 illustrates an example in which the Walsh code is split in time into an even-numbered PCG and an odd-numbered PCG to define two base channels, and in which traffic information is encoded at a 1/2 coding rate, and in which identical traffic information transmitted in two base channels. In this case, the coding rate of each base channel becomes 1. Also, for the receiving side to successfully receive information, the receiving side must receive identical traffic information from two or more base channels.

Referring to FIG. 23, each of the base channels receives a bit sequence that passes through an identical interleaver to independently perform a cyclic shift for each base channel. Then the cyclically shifted result is spread-spectrum encoded and modulated using the Walsh code allocated for each base channel, thereby transmitting a signal from the PCG allocated for each base channel. In this document, no signal is transmitted from an unallocated PCG. 23, the order of the spreading coding module and the modulator and the PCG selection module may change.

Two base channels, F-PTCH and F-STCH, are allocated to a mobile station in a non-handover area in order to successfully receive traffic information. When the cyclic shift values of F-PTCH and F-STCH are 0, when the Walsh code indices of each of the F-PTCH and F-STCH are identical to each other, and when the F-PTCH is allocated to the PCG with an odd frame number, and when the F-STCH is allocated for an even-numbered PCG, the transmitted side signal of an embodiment of the present invention becomes identical to the transmitted side signal of the prior art.

24 illustrates another example of a transmit side of a transmission chain using a wireless structure according to an embodiment of the present invention.

As shown in FIG. 24, the bit sequence after speed matching is divided into two sequences by means of a conversion unit (or module) from serial to parallel. Then, each of the sequences is interleaved and cyclically shifted, and thus is spread-spread encoded and modulated. In addition, the modulated signal is converted to a PCG allocated to the base channel in order to be transmitted.

The following describes an example of using a wireless structure according to an embodiment of the present invention surrounded by soft handoff.

25 illustrates a communication process between two base stations using wireless structures and a mobile station in a handover mode according to an embodiment of the present invention.

Referring to FIG. 25, when the F-PTCH cyclic shift value is 0, when the output sequence length of the interleaver is N, and when the F-STCH cyclic shift value is N / 16, when the Walsh code indices of each of the F-PTCH and F- STCHs are identical to each other, and when the F-PTCH and F-STCH are allocated to the PCG with an odd frame number so transmitted, the signal transmission has a 50% duty cycle in PCG units. Thus, when combined with the early termination method, the signal power unnecessarily transmitted during the early termination process and receiving ACK feedback may decrease.

FIG. 26 illustrates an example handover process using a wireless structure according to an embodiment of the present invention. FIG. 27 also illustrates another exemplary handover process using a wireless structure according to an embodiment of the present invention.

Referring to FIG. 26, when the mobile station connects to the first base station (BS1), the mobile station receives data from the first base station via F-PTCH and F-STCH. Here, the F-PTCH cyclic shift value is 0, and the F-STCH cyclic shift value is N / 16.

After that, the mobile station is shifted to the second base station (BS2), and when the ratio of power-carrier- (or-pilot-signal)-to-interference (hereinafter referred to as C / I) exceeds the threshold value for adding a traffic channel (threshold value T_ADD), the base station controller (BSC) notifies the mobile station that the F-PTCH of the second base station is allocated to the mobile station through a handover message. Accordingly, after the F-PTCH is received normally by the second base station, when the mobile station transmits a handover complete message to the base station controller, the base station controller can verify that the handover process of the mobile station is completed. Here, when the F-PTCH cyclic shift value of the second base station is (N / 2 + N / 16), the benefit from soft handoff with code combining can be maximized.

In addition, when the pilot C / I of the first base station is below a predetermined threshold, the base station controller notifies the mobile station that the F-STCH of the first base station is released through a handover message. After the mobile station normally receives the message and transmits the handover complete message to the first base station, the first base station stops (or interrupts) the F-STCH transmission and then extracts the Walsh code source that is allocated to the mobile station.

When the mobile station moves additionally to the second base station and when the pilot C / I received from the second base station exceeds a predetermined threshold value, the base station controller notifies the mobile station that the F-STCH of the second base station is allocated to the mobile station, through a handover message. Here, when the F-PTCH cyclic shift value of the second base station is N / 2, the benefit from soft handoff with code combining can be maximized.

In addition, when the pilot C / I received from the first base station falls below the traffic channel drop threshold (T_Drop threshold), the base station controller notifies the mobile station that the F-PTCH of the first base station is released (or discarded), through a handover message. After the mobile station normally receives the handover message and transmits the handover complete message to the first base station, the first base station stops (or interrupts) the F-PTCH transmission and then extracts the Walsh code source that is allocated to the mobile station.

In the example shown in FIG. 26, between the transmission point of the second handover message and the transmission point of the third handover message, the first base station and the second base station transmit only the F-PTCH to the mobile station.

On Fig, the release of the F-STCH of the first base station and the allocation of the F-STCH of the second base station is carried out simultaneously. More specifically, the mobile station can be allocated F-PTCH from N base stations in the field of N-way transmission service. Also then, the F-STCH from one optimal base station can be allocated to the mobile station. Alternatively, the mobile station may be allocated F-PTCH from N base stations in the field of N-way transmission service. Also then, the F-STCH from some of the N base stations may also be allocated to the mobile station.

As described above, when the wireless structure according to an embodiment of the present invention is used, the Walsh code source allocated from each base station within the N-way handoff area is halved compared to the conventional method. Thus, the phenomenon of inaccuracy of the source of Walsh codes can be solved.

In the example shown in FIG. 25, both the F-PTCH and the F-STCH are allocated to the PCG with an odd number of all frames. Consequently, the gain from early termination may increase. However, the problem of an imbalance in the frequency of use of the Walsh code source corresponding to the odd-numbered PCG and the even-numbered PCG may occur. Therefore, in order to solve this problem, a method is provided that provides independent and flexible PCG isolation for each of the F-PTCH and F-STCH.

25, the F-PCSCH is punctured in the F-PTCH and then transmitted. More specifically, during the F-PTCH isolation process, F-PCSCH isolation is performed simultaneously. On the contrary, the control channel is thinned in the F-STCH, and thus, the allocation does not occur here. Therefore, in the handover process of the mobile station, the F-PTCH is allocated from all base stations of the active sector, and the F-STCH is allocated to the mobile station when required. In addition, for early termination of the reverse link channel, the base station transmits F-ACKSCH in the forward direction. However, in FIG. 25, the F-ACKSCH is time division multiplexed (by a time division multiplexer (TDM)) with other indicator signals and transmitted to the indicator direct channel (hereinafter referred to as F-ICCH).

FIG. 28 illustrates an exemplary F-PCSCH and F-ACKSCH control channel structure when using a wireless structure according to an embodiment of the present invention.

In Fig. 28, the base station does not additionally use the F-ICCH, but decimates the F-PCSCH and F-ACKSCH in the F-PTCH, which is then transmitted. In the example shown in FIG. 28, a source of Walsh codes for the F-ICCH is not required. However, there is a drawback that the F-PTCH is over-thinned.

29 illustrates another exemplary F-PCSCH and F-ACKSCH control channel structure using a wireless structure according to an embodiment of the present invention.

29, the base station time division multiplexes the F-PCSCH and F-ACKSCH in the F-ICCH with other indicator signals, which are then transmitted. The example shown in FIG. 29 is advantageous in that the transmission rate of the power control command and the transmission rate of the ACK can be freely selected. In addition, since there are no priority levels for the base channels, when allocating channels, the allocation and release of F-TCH1 and F-TCH2 can be freely determined.

FIG. 30 illustrates yet another exemplary structure of an F-PCSCH and F-ACKSCH control channel using a wireless structure according to an embodiment of the present invention. In Fig. 30, the base station decimates the F-PCSCH in F-TCH1, which is then transmitted, and also decimates the F-ACKSCH in F-TCH2, which is then transmitted.

Embodiments of the present invention may be implemented by various means, such as hardware, firmware, software, and a combination of hardware, firmware, and / or software. When implementing an embodiment of the present invention in the form of hardware, a standby method in a wireless communication system according to an embodiment of the present invention can be implemented by one or a combination of specialized integrated circuits (ASICs), digital signal processors (DSP), digital signal processing devices ( DSPD), programmable logic devices (PLD), user-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocesses orov, etc.

When implementing an embodiment of the present invention in the form of firmware or software, a standby method in a wireless communication system according to an embodiment of the present invention can be implemented in the form of a module, process, function, etc. that perform the above functions and / or operations. The program code may be stored in a storage device and controlled by a processor. The storage device may be located within or outside the processor, thereby receiving and transmitting data from and to the processor by using a variety of disclosed means.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the technical and fundamental nature and scope of the invention. Therefore, a detailed description of the present invention should not be interpreted as limiting in all aspects of the present invention, but should be considered as exemplary. The scope of the appended claims of the present invention should be determined based on a rational interpretation, and all modifications within the scope of the appended claims and their equivalents should be included in the scope of the present invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the claims and their equivalents.

It should also be apparent that the preferred embodiments can be configured by combining unquoted claims within the scope of the attached claims, or can be added as new modified claims after filing a patent application of the present invention.

Claims (18)

1. A method of receiving data from a mobile station during soft handoff in a wireless communication system, the method comprising the steps of:
receiving a sequence from the first base station, the sequence from the first base station being formed by interleaving the transmitted data using the first interleaver module template; and
receiving a sequence from a second base station, the sequence from a second base station being formed by interleaving the transmitted data using the second interleaver module template,
combine the sequence from the first base station and the sequence from the second base station and decode the combined sequence to receive the entire frame having the sequence from the first base station and the sequence from the second base station allocated to it,
wherein the sequence from the second base station corresponds to the sequence from the first base station shifted cyclically, and
wherein the point at which the mobile station is trying to decode the combined sequence is reported to the mobile station through the first base station. 2. The method of claim 1, further comprising transmitting the ACK to the first base station and to the second base station when decoding is successfully completed. 3. The method according to claim 1, in which the sequence from the second base station corresponds to the sequence from the first base station cyclically shifted by the length of the sequence from the first base station, divided by 2. 4. The method according to claim 1, in which the sequence from the first base station and the sequence from the second base station are encoded using convolutional codes. 5. The method according to claim 1, in which the transmitted data corresponds to voice data. 6. A mobile station receiving data during soft handoff in a wireless communication system, the mobile station comprising:
a receiving module receiving a sequence from the first base station, the sequence from the first base station being generated by interleaving the transmitted data using the first interleaving module template, and a receiving sequence from the second base station, the sequence from the second base station being generated by interleaving the transmitted data using the second an interleaver module template; and
a decoder combining the sequence from the first base station and the sequence from the second base station and decoding the combined sequence before receiving the entire frame having the sequence from the first base station and the sequence from the second base station allocated to it,
wherein the sequence from the second base station corresponds to the sequence from the first base station shifted cyclically, and
wherein the point at which the mobile station is trying to decode the combined sequence is reported to the mobile station through the first base station. 7. The mobile station according to claim 6, in which the sequence from the second base station corresponds to the sequence from the first base station cyclically shifted by the length of the sequence from the first base station, divided by 2. 8. The mobile station of claim 6, wherein the mobile station transmits the ACK to the first base station and to the second base station when decoding is successfully performed. 9. The mobile station according to claim 6, in which the sequence from the first base station and the sequence from the second base station are encoded using convolutional codes. 10. The mobile station according to claim 6, in which the transmitted data corresponds to voice data. 11. A method of transmitting data from a first base station communicating with a mobile station during soft handoff in a wireless communication system, the method comprising the steps of:
transmitting the sequence to the mobile station, the sequence being formed by interleaving the transmitted data using the first template of the interleaving module; and
interrupt the transmission of a frame having a sequence allocated to it when an acknowledgment of receipt (ASK) is received from the mobile station,
the sequence is formed by interleaving the transmitted data using the second template of the interleaving module by the second base station and transmitting in a frame from the second base station to the mobile station, the second base station communicating with the mobile station,
wherein the mobile station combines the sequence from the first base station and the sequence from the second base station and decodes the combined sequence before receiving the entire frame having the sequence from the first base station and the sequence from the second base station allocated to it,
wherein the sequence from the second base station corresponds to the sequence from the first base station shifted cyclically, and
wherein the point at which the mobile station is trying to decode the combined sequence is reported to the mobile station through the first base station. 12. The method according to claim 11, in which the sequence from the second base station corresponds to a sequence from the first base station cyclically shifted by the length of the sequence from the first base station, divided by 2. 13. The method according to claim 11, in which the sequence from the first base station and the sequence from the second base station are encoded using convolutional codes. 14. The method according to claim 11, in which the transmitted data corresponds to voice data. 15. A base station communicating with a mobile station in soft handoff in a wireless communication system, said base station comprising:
an encoder for encoding the transmitted data; and
an interleaver for generating a sequence by interleaving the encoded transmitted data using the first interleaver module template, and
a transmitter for transmitting the generated sequence in the frame to the mobile station, wherein said base station stops transmitting a frame having a sequence from said base station allocated to it when an acknowledgment (ACK) is received from the mobile station, and
wherein the sequence is formed by interleaving the transmitted data using the second template of the interleaving module by another base station and transmitted in a frame from said other base station to the mobile station, said other base station communicating with the mobile station,
wherein the mobile station combines a sequence from said base station and a sequence from said other base station and decodes the combined sequence before receiving the entire frame having a sequence from said base station and a sequence from said other base station allocated to him,
wherein the sequence from said other base station corresponds to the sequence from said base station shifted cyclically, and
wherein the point at which the mobile station is attempting to decode the combined sequence is reported to the mobile station through said base station. 16. The base station according to claim 15, wherein the sequence from said other base station corresponds to a sequence from said base station cyclically shifted by the length of the sequence mentioned from the base station, divided by 2. 17. The base station according to clause 15, in which the encoder uses convolutional codes to encode the transmitted data. 18. The base station according to clause 15, in which the transmitted data corresponds to voice data.

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