KR20040107784A - Metode for demodulating high speed downlink packet data in communication system using high speed downlink packet access scheme - Google Patents

Abstract

PURPOSE: A method for demodulating high-speed downlink packet data is provided to reduce power consumption of a terminal by preventing previously unnecessary demodulation without using an additional hardware or an additional software. CONSTITUTION: A method for demodulating high-speed downlink packet data includes a production process and a demodulation prevention process. The production process is performed to produce a predetermined point prior to a predetermined time interval from a starting point of a transmission gap. The demodulation prevention process is performed to process high-speed shared control channel signals received from the produced point without demodulating the high-speed shared control channel signals.

Description

TECHNICAL FOR DEMODULATING HIGH SPEED DOWNLINK PACKET DATA IN COMMUNICATION SYSTEM USING HIGH SPEED DOWNLINK PACKET ACCESS SCHEME}

The present invention relates to a mobile communication system, and more particularly, to a method for demodulating high speed forward packet data in a communication system using a high speed forward packet access scheme.

The mobile communication system has evolved into a high speed, high quality wireless data packet communication system for providing data service and multimedia service, away from the conventional voice-oriented service provision. Currently, the standardization of High-Speed Downlink Packet Access (HSDPA) and 1xEV-DV, which is currently being conducted around 3GPP and 3GPP2, is a high-speed, 2Mbps or higher speed in 3G mobile communication system. It is a representative example of an effort to find a solution for a high quality wireless data packet transmission service.

In general, the HSDPA scheme is referred to as a high speed downlink shared channel (HS-DSCH), which is a forward data channel for supporting forward high speed packet data transmission in a universal mobile terrestrial system (UMTS) communication system. And a control channel related thereto. The HS-DSCH is also referred to as a HS-PDSCH (High Speed-Physical Downlink Shared Channel), which means transmission of a physical layer.

Adaptive Modulation and Coding (AMC), Hybrid Automatic Retransmission Request (HARQ) and Fast Cell Selection (Fast Cell) to support the HSDPA Select (hereinafter referred to as 'FCS') has been proposed. Briefly, the features applied to the HSDPA scheme are as follows.

First, the AMC method will be described.

The AMC scheme is a modulation scheme of different data channels depending on a channel state between a specific base station (Node B; hereinafter referred to as 'Node B') and a terminal (UE; User Element, hereinafter referred to as 'UE'). And a data transmission method for determining the coding method and improving the use efficiency of the entire base station. Accordingly, the AMC scheme has a plurality of modulation schemes and a plurality of coding schemes, and modulates and codes a data channel signal by combining the modulation schemes and coding schemes. Typically, each of the combinations of modulation schemes and coding schemes is referred to as a modulation and coding scheme (hereinafter, referred to as 'MCS'), and is level n to level n depending on the number of MCSs. Up to a plurality of MCSs can be defined. That is, the AMC scheme is a scheme for adaptively determining the level of the MCS according to a channel state between the UE and a Node B which is currently wirelessly connected, thereby improving overall Node B overall system efficiency.

Secondly, the HARQ scheme, in particular, the n-channel Stop And Wait Hybrid Automatic Retransmission Request (hereinafter referred to as 'n-channel SAW HARQ') will be described.

The HARQ scheme newly applies the following two methods to increase the transmission efficiency of the ARQ (Automatic Retransmission Request) scheme. The first scheme is to perform the retransmission request and response between the UE and the Node B. The second scheme is to temporarily store the data in error and combine it with the retransmission data of the corresponding data. will be.

In addition, the HSDPA scheme has introduced the n-channel SAW HARQ scheme to compensate for the disadvantages of the conventional Stop and Wait ARQ (SAW ARQ) scheme. In the SAW ARQ scheme, the next packet data is transmitted only after receiving an ACK for the previous packet data.

However, since the next packet data is transmitted only after receiving the ACK for the previous packet data as described above, there may occur a case where the ACK must be waited even though the packet data can be transmitted at present. In the n-channel SAW HARQ scheme, a plurality of packet data may be continuously transmitted without receiving an ACK for the previous packet data, thereby improving channel usage efficiency.

That is, if the n logical channels are established between the terminal and the base station, and each of the n channels is identifiable by a specific time or channel number, the UE that receives the packet data is received at any time. It is possible to know which packet data is transmitted through which channel, and may take necessary measures such as reconfiguring the packet data in the order in which it is to be received or soft combining the packet data.

Finally, the FCS method will be described.

The FCS scheme is a method of quickly selecting a cell having a good channel state among a plurality of cells when the terminal using the HSDPA scheme is located in a cell overlap region, that is, a soft handover region. Specifically, the FCS scheme includes: (1) when a terminal using the HSDPA enters a cell overlapping area between an old base station and a new base station, the terminal may include a plurality of cells, that is, a radio link with a plurality of base stations. Radio link '). In this case, a set of cells in which a radio link is established with the terminal is called an active set. (2) Receive packet data for HSDPA only from cells that maintain the best channel state among the cells included in the active set to reduce the overall interference.

Herein, a cell transmitting HSDPA packet data because the channel state is the best in the active set is called a best cell, and the terminal periodically checks the channel state of the cells belonging to the active set and compares it with the current best cell. When a cell having a better channel state occurs, a best cell indicator or the like is transmitted to cells belonging to the active set to change the current best cell into a cell having a better channel state.

The best cell indicator includes an identifier of a cell selected as a best cell and is transmitted. Accordingly, cells in the active set receive the best cell indicator and examine a cell identifier included in the best cell indicator. Thus, each of the cells in the active set checks whether the best cell indicator corresponds to its best cell indicator, and the corresponding cell selected as the best cell is a packet to the terminal using a fast forward common channel (HS-DSCH). Send the data.

1 is a diagram schematically illustrating a forward channel structure of a communication system using a conventional high speed forward packet access scheme.

Referring to FIG. 1, fast forward packets are transmitted through the HS-DSCH channel and information for the HS-DSCH control is transmitted through the HS-SCCH. One user receives information for control through one channel of up to four HS-SCCHs. The following information is present in the HS-DSCH control information transmitted through the HS-SCCH.

(1) Transport Format and Resource related Information (hereinafter referred to as 'TFRI')

The TFRI indicates an MCS level to be used in the HS-DSCH, channelization code information of the HS-DSCH, a size of a transport block set, and an identifier of a transport channel.

(2) HARQ information

(a) HARQ process number: n-channel When SAW HARQ is used, it informs a channel to which specific packet data belongs among logical channels for HARQ.

(b) HARQ packet number: When the best cell is changed in the FCS, the UE informs the UE of the number of forward packet data so that the UE can inform the newly selected best cell of the transmission state of the HSDPA data.

In addition, one or more channelization codes may be allocated to the SCCH. For example, in FIG. 1, up to four SCCHs can be allocated to each of the UEs. Therefore, the HI of the DPCH informs the information on the SCCH to be received by the UE with the presence or absence of the HSDPA data packet to be received. Since the number of SCCHs can be allocated up to 4, two bits (2 bits) of HI may inform the information about the SCCH to be received by the UE. For example, if HI is 00, the UE receives SCCH # 1, 01 receives SCCH # 2, 10 receives SCCH # 3, and 11 receives SCCH # 4.

In addition, the HS-DSCH is a channel through which HSDPA packet data transmitted by the base station to the UE is transmitted. Since the base station needs to transmit high-speed packet data to the HS-DSCH, an Orthogonal Variable Spreading Factor (hereinafter referred to as 'SFSF') having a significantly low Spreading Factor (SF) in the HS-DSCH is referred to as 'OVSF'. ) Assign code. For example, an OVSF code having an SF of 16 may be allocated to the HS-DSCH.

Next, a process of receiving the HSDPA service by the UE using three channels as described above, that is, DPCH, SCCH, and HS-DSCH will be described.

When the HSDPA packet service is started, the UE demodulates the HS-SCCH signals and uses the demodulated information to check the information of the HS-SCCH allocated thereto. This process is possible because the user's unique number is used to generate the information to be delivered to the HS-SCCH. The HS-SCCH signal is decoded to extract the MCS level, channelization code information, and HARQ related control information of the HS-DSCH necessary for demodulating the HS-DSCH channel. Finally, the UE receives the HSDPA packet data by receiving, demodulating and decoding the HS-DSCH signal using the control information detected through the HS-SCCH.

As described above, in order to demodulate the HS-DSCH signal, the UE must detect the corresponding control information by reading the HS-SCCH signal. That is, as shown in FIG. 1, the UE first receives an HS-SCCH signal to read control information and then receives an HS-DSCH channel. The reason why the HS-SCCH is transmitted first is because it is not known whether the data is applicable to the UE before the HS-SCCH control information is read. Therefore, data transmitted through the HS-DSCH must be temporarily stored in a buffer. This is to reduce the UE buffer burden.

2 shows an example of a method of configuring a reverse dedicated physical channel supporting HSDPA.

Separate channelization codes are assigned to the Reverse Dedicated Physical Data Channel (DPDCH) supporting Release-99, the Reverse Dedicated Physical Control Channel (DPCCH), and the Reverse Dedicated Physical Control Channel (HS-DPCCH) to support HSDPA. By operating separately.

In addition, if the existing reverse control channel is modified, there may be a problem in compatibility with the existing system and the channel structure may be very complicated. Therefore, a new channelization code may be used to provide a method of newly defining the reverse control channel. have.

The upper layer data transmitted from the terminal to the base station is transmitted through respective slots constituting one frame of the reverse dedicated physical data channel (DPDCH) for supporting Release-99, and one frame of the reverse dedicated physical control channel is transmitted. Each of the slots is composed of a pilot symbol, a transmission format combination indication (TFCI) bit, an FBI symbol, and a transmission output control symbol (TPC).

The pilot symbol is used as a channel estimation signal when the terminal demodulates data transmitted to the base station, and the TFCI bits indicate which transmission type combinations are used by the channels transmitted during the frame currently being transmitted.

The FBI symbol transmits feedback information when using transmit diversity technology, and the transmit power control symbol (TPC) is for controlling the transmit output of the forward channel. The reverse dedicated physical control channel is spread by being transmitted using an orthogonal code, and the spreading factor (SF) used is fixed at 256.

In the HSDPA, the user terminal checks whether the data transmitted by the base station is in error and transmits the result as an acknowledgment signal (ACK) or a negative acknowledgment signal (NACK), and the backward dedicated physical control channel HS to support the HSDPA. DPCCH transmits. In the present invention, information indicating whether or not the transmitted data is error is called ACK / NACK. In addition, in order to support AMC, the terminal may transmit information reporting channel quality to the base station. In the present invention, the downlink channel quality information is referred to as a channel quality indicator (CQI).

In FIG. 2, the ACK / NACK is transmitted over one slot of subframes of the HS-DPCCH channel, and CQI information is transmitted over the other two slots. When the terminal does not need to transmit the ACK / NACK or CQI information, the ACK / NACK or CQI field is DTX processed.

On the other hand, in cellular networks in which communication connections are separated from each other using Code Division Multiple Access (CDMA) technology, a mobile station having an active communication connection with the cellular network is in fact always associated with the communication connection. It must be able to receive data at radio frequencies.

In addition, in interfrequency handover, the frequency at which the active communication connection is present may be changed. Cell change may involve such inter-frequency handovers, in which case the method is intercell-interfrequency handovers.

In order to perform interfrequency handover between communication connections having a plurality of frequency bands in the mobile communication system, the mobile station performs reception power measurement on a cell having a plurality of frequency bands. For example, while performing communication in the first frequency band, the received power for the adjacent second frequency band is measured.

When a period for measuring the reception power for the first frequency band is called a normal mode, a period for measuring the reception power for the second frequency band is called a compressed mode, and the second The reception power measurement for the frequency band is called interfrequency measurement. The reception power measurement for the second frequency band is shorter than the reception power measurement period for the first frequency band, and performs power measurement during the compression mode intermittently between periods for the normal mode.

Meanwhile, the UMTS system uses HS-SCCH and HS-DSCH for downlink and HS-DPCCH for uplink for the HSDPA. As described above, the HS-SCCH transmits information on the HS-DSCH and information related to demodulation, information required for HARQ and channel decoding. The HS-DSCH is a physical channel for transmitting a packet. In addition, the uplink HS-DPCCH transmits ACK / NACK information, which is a channel decoding result of the HS-DSCH, and CQI information for adaptive modulation and coding (AMC) to the base station.

3 is a diagram illustrating a time relationship diagram of an HS-SCCH, an HS-DSCH, and an uplink HS-DPCCH.

The HS-SCCH, HS-DSCH, and HS-DPCCH are processed in subframe units of 3 slots. After the HS-SCCH is transmitted, the corresponding HS-DSCH is transmitted after 2 slots (ie, 5120 chips). In addition, ACK / NACK information indicating the decoding result of the corresponding HS-DSCH is transmitted to the first slot of the HS-DPCCH when the time of 7.5 slots (that is, 19200 chips) has elapsed after the transmission of the subframe of the HS-DSCH. Load it up and send it.

That is, the HS-SCCH, HS-DSCH and HS-PDCCH, which are channels for HSPDA, are transmitted while maintaining a predetermined constant time interval as described above.

4 is a block diagram of a receiving apparatus for DPCH and HSDPA physical channel processing of a terminal supporting HSDPA.

Referring to FIG. 4, a signal received through an antenna is input to a DPCH rake receiver / demodulator 410 and an HSDPA rake receiver / demodulator 420 for processing DPCH data and data for HSPDA. The signal input to the DPCH rake receiver / demodulator 410 demodulates the DPCH data and decodes it in the downlink DPCH channel decoder 440.

Meanwhile, the DPCH data, which is uplink data transmitted from the terminal to the base station, is composed of a DPDCH, which is uplink transmission data, and a DPCCH including control information. Here, the DPCCH data is determined by the signal received through the downlink as described above.

That is, in FIG. 4, the DPDCH data generated by the uplink DPCH channel encoder 430 and the DPCCH data generated from the value received through the downlink DPCH channel decoder 440 are converted into DPCH signals by the uplink DPCH modulator 460. It is combined and transmitted through the antenna.

Meanwhile, the HSDPA data demodulated by the HSDPA Rake receiver and demodulator 420 is decoded by the HSDPA channel decoder 450. Similarly, the uplink HS-DPCCH modulator 470 generates HS-DPCCH data through the information determined according to the decoding result of the downlink channel and transmits it through the antenna.

As described above, the UMTS system, which is a third generation mobile communication system, supports handover between systems having different frequency bands. For this purpose, the terminal uses the above-mentioned compressed mode. The compression mode refers to a series of operations for creating a transmission gap at a predetermined time with a Node B while receiving a DPCH, and identifying characteristics of different frequency bands during the transmission gap.

The HSDPA receiving terminal should be designed in consideration of the operation in the compression mode of the downlink and uplink DPCH. In particular, when the terminal determines that it is impossible to properly receive or transmit any one channel of the HS-SCCH, HS-DSCH, and HS-DPCCH due to the transmission gap, the terminal should perform an appropriate operation accordingly. The current UMTS standard proposes the following conditions for uplink and downlink operation of a terminal supporting HSDPA in relation to the compression mode.

1) If a part of the received HS-SCCH or HS-DSCH overlaps the transmission gap of the associated downlink DPCH, the corresponding transmitted HS-SCCH or HS-DSCH is ignored. In this case, ACK / NACK information for the corresponding downlink transmission should not be transmitted by the terminal.

2) When a part of the ACK / NACK transmission slot of the uplink HS-DPCCH overlaps the transmission gap of the associated uplink DPCH, the terminal should not transmit ACK / NACK information to the corresponding ACK / NACK slot.

3) When a part of the slot related to the CQI transmission of the uplink HS-DPCCH overlaps the transmission gap of the associated uplink DPCH, the terminal should not transmit the corresponding CQI information to the CQI slot.

Until now, there is no proposal for operation control of downlink HS-SCCH, HS-PDSCH, and HS-DPCCH for HSDPA in a compression mode that satisfies the above standard, and unnecessary demodulation is performed in applying the above conditions. There is a problem.

There is a method of applying all of the above conditions and stopping all operations at the time when transmission gap starts and resetting all operations related to the decoding for the frames being decoded. In other words, even if a transmission gap is encountered during channel decoding while receiving input, compression mode can be implemented by stopping channel decoding and flushing all data. That is, even if the terminal receives a normal HS-SCCH, if a transmission gap occurs at a time when the HS-DSCH or HS-DPCCH needs to be demodulated, the terminal stops demodulation or modulation at that moment, and thus the HS-DSCH or HS. -Normal transmission / reception of the DPCCH is not performed, and thus, a problem arises in that power loss is caused by unnecessary demodulation of the HS-SCCH.

Accordingly, an object of the present invention is to provide a method for demodulating the fast forward packet data when packets related to the fast forward packet transmission are transmitted in a transmission blank period in a communication system using a fast forward packet access scheme.

The method according to the first embodiment of the present invention for achieving the above object, in the communication system using a high-speed forward packet access method, when the packets associated with the high-speed forward packet transmission is transmitted in the transmission blank period, the high speed forward packet A method of demodulating data, the method comprising: calculating a time point before a predetermined time interval from a start time of a transmission gap and processing a demodulated high-speed forward common control channel (HS-SCCH) signal received from the calculated time; It is characterized by including the process.

In the method according to the second embodiment of the present invention for achieving the above object, the transmission time of the uplink HS dedicated physical control channel (Uplink HS-DPCCH) signal in the communication system using a high-speed forward packet access method is a transmission blank In the method of demodulating the high speed forward packet data when it is not normally transmitted, the method includes: checking a new data indicator of a newly received fast forward common control channel; and checking the identified new data indicator and a previously received fast forward common channel. And determining whether to demodulate the HS-DSCH signal received thereafter in consideration of normal demodulation of the (HS-DSCH).

In the method according to the third embodiment of the present invention for achieving the above object, the transmission time of the uplink HS dedicated physical control channel (Uplink HS-DPCCH) signal in the communication system using a high-speed forward packet access method is a transmission blank In the method of demodulating high-speed forward packet data when it is not normally transmitted, the method includes: calculating a time point before a predetermined time interval from a start time of a transmission gap; and a high speed forward common control channel received from the calculated time. (HS-SCCH) signal processing without demodulation.

1 illustrates channels forwarded for HSDPA service.

2 is a diagram illustrating a channel configuration of a reverse dedicated physical channel.

3 shows the temporal relationship of channels for the HSDPA scheme.

4 is a block diagram illustrating DPCH and HSDPA physical channel processing in a receiver of a UMTS terminal supporting an HSDPA scheme.

5 is a diagram illustrating a time relationship when the HS-SCCH can be decoded in the HSDPA scheme according to the first embodiment of the present invention, but the decoding of the HS-DSCH is impossible.

6 is a diagram illustrating a time relationship when decoding of HS-SCCH and HS-DSCH is possible in the HSDPA scheme according to the first embodiment of the present invention.

FIG. 7 illustrates a time relationship when ACK / NACK information cannot be transmitted due to a transmission gap in the HSDPA scheme according to the second embodiment of the present invention.

8 is a diagram illustrating a time relationship when ACK / NACK information cannot be transmitted due to an uplink transmission gap in the HSDPA scheme according to the third embodiment of the present invention.

9 is a flowchart illustrating a decoding procedure of the HS-DSCH in the HSDPA scheme according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted without departing from the scope of the present invention.

The present invention provides a method of preventing unnecessary demodulation of all uplink and downlink data associated with fast forward packet access by a compression mode. Meanwhile, three embodiments are presented as a method of determining whether demodulation is due to the effect of transmission white space in the compression mode according to the present invention.

As embodiments of the present invention, first, parameters that are determined for support of a compression mode are used, and a method of using a predetermined non-demodulated HS-SCCH in consideration of the effects of the uplink and downlink due to the transmission gap, and using the same, downlink Considering only the effect of the three methods can be considered that do not demodulate the HS-SCCH.

<First Embodiment-Method Considering Only the Effect of Downlink>

First, with reference to FIGS. 5 and 6, a method of determining a non-demodulated HS-SCCH according to only a downlink effect according to a first embodiment of the present invention will be described.

In the aforementioned compression mode, transmission gaps of downlink and uplink may be considered separately. Therefore, as suggested in the standard, downlink transmission gap is considered for the downlink channels HS-SCCH and HS-DSCH in the HSDPA scheme, and uplink transmission gap is considered for the uplink channel HS-DPCCH.

In implementing the method of the first embodiment, only the case of the HS-SCCH and the HS-DSCH associated with the downlink transmission gap is considered.

5 and 6 illustrate an influence relationship in a case where a start slot of a transmission gap may be based on the HS-DSCH in the compression mode. In particular, FIG. 5 illustrates a time relationship when the HS-SCCH can be decoded in the HSDPA scheme, but the decoding of the HS-DSCH is impossible.

Referring to FIG. 5, if the transmission gap TG spans the corresponding slot of the HS-DSCH, the HS-DSCH is preferably not demodulated and decoding of the HS-DSCH affected by the transmission gap. It is also desirable not to demodulate the corresponding HS-SCCH containing information. In order to satisfy the above condition, the decoding process should not be performed for all HS-SCCHs that start between the time after the maximum 5 slots before the start of the transmission gap and the end of the transmission gap.

The reason to consider from the channel received before 5 slots of the transmission gap as described above is that the HS-SCCH and HS-DSCH are decoded in subframes, that is, 3 slot units, respectively, as described above. This is because the corresponding HS-DSCH is received with a difference of two slots from each other.

That is, the HS-SCCH and its associated HS-DSCH are all decoded within 5 slots. Therefore, assuming that the slot of the HS-SCCH is already being received at the time before the 5 slots of the transmission gap, decoding of the HS-SCCH and the corresponding corresponding HS-DSCH can be completed before reaching the transmission gap. have.

FIG. 6 is a diagram illustrating a time relationship when decoding of HS-SCCH and HS-DSCH is possible in an HSDPA scheme according to an embodiment of the present invention.

Referring to FIG. 6, since the first slot of the HS-SCCH has already been received at the time before 5 slots of the transmission gap as described above, the HS-SCCH and the 3 slots in time within 5 slots thereafter. Decoding of the corresponding HS-DSCH of three slots corresponding to the HS-SCCH may be completed. On the other hand, it is preferable not to decode the HS-SCCH received in the transmission space or received after 5 slots before the transmission space.

In the present invention, for convenience of description, the period from the start of the transmission blank to the time before the 5 slots including the transmission blank period is defined as the compression mode period (COMP_MODE). That is, according to the present invention, since the HS-SCCH data starting to be received after the start of the compression mode period cannot be decoded for the corresponding HS-DSCH, it is preferable not to decode.

The starting point of the transmission gap of the downlink DPCH is given in advance from the base station. In addition, since the difference between the subframe boundary of the HS-SCCH and the frame boundary of the downlink DPCH is also given, even the boundary value between the slots of the HS-SCCH can be calculated from the time point five slots before the start of the transmission gap.

Meanwhile, the time point at which the HS-SCCH is received again is from the boundary of the first HS-SCCH subframe received after the transmission gap of the DPCH ends. At this time, the demodulation of the HS-SCCH is normally performed, and then the demodulation of the HS-DSCH corresponding to the HS-SCCH is performed.

<Calculation example of demodulation possible with actual parameter value>

The subframe of the HS-SCCH has an offset of {0, 3, 6, 9, 12} slots based on a boundary of a COMPI (Commno PIlot CHannel) frame. In addition, the DPCH frame has a time offset with respect to the CPICH frame. Therefore, by using the information of the time offset and the time information on the downlink compression mode, it is possible to calculate the slot time difference between the HS-SCCH and DPCH, the time information for the actual operation by calculating the times for the convenience of implementation A signal indicating may be defined and used.

For example, the signal called the compression mode period COMP_MODE described above with reference to FIGS. 6 and 7 corresponds to the signal. The compression mode period signal indicates the demodulation stop of the HSDPA related channel for the time from the DPCH slot before 5 slots to the slot where the transmission gap ends at the transmission blank start position of the DPCH. The start time of the COMP_MODE may also be determined using the difference between the downlink DPCH and the HS-SCCH slots as described above. The terminal observes the compression mode period signal at the start of the sub-frame of the HS-SCCH, and if the compression mode period signal indicates the demodulation stop, the terminal stops demodulation of the HS-SCCH and is received two slots later. Demodulation is not performed on the HS-DSCH corresponding to the HS-SCCH.

<Second Embodiment-Method of Considering Only Uplink Effect>

Hereinafter, a method of controlling demodulation in consideration of the effect of uplink according to the second embodiment of the present invention will be described with reference to FIG. 7.

FIG. 7 illustrates a time relationship when ACK / NACK information cannot be transmitted due to a transmission gap in the HSDPA scheme according to the second embodiment of the present invention.

Referring to FIG. 7, the HS-SCCH and the HS-DSCH are demodulated because they are not included in the downlink transmission blank period, but the ACK / NACK information is overlapped with the transmission blank by the ACK / NACK transmission part of the uplink HS-DPCCH. Failure to do so may occur. The transmission gap of the DPCH generally ranges from 3 slots to 14 slots. Accordingly, as shown in FIG. 8, since the transmission gap is long, demodulation of the HS-SCCH and HS-DSCH is possible, but ACK / NACK information, which is a decoding result of the HS-DSCH, cannot be transmitted through the uplink HS-DPCCH. Cases may occur. That is, as described above, when the HS-DSCH and the uplink HS-DPCCH are transmitted / received with a difference of 7.5 slots, when the transmission gap starts between the HS-DSCH and the uplink HS-DPCCH, The situation arises.

In this case, when the HS-DSCH having the same HARQ process ID (Process ID) is transmitted in the next slot in which the terminal is received, ACK / NACK information that is the decoding result of the HS-DSCH and new data of the HS-SCCH The new data indicator information is used to determine whether to decode the newly received HS-DSCH.

That is, even if the uplink HS-DPCCH is not normally transmitted to the base station, since the HS-SCCH and the HS-DSCH are normally decoded, the base station that has not received the normal ACK / NACK signal retransmits the same packet. Even in this case, the terminal can selectively decode according to whether the previously decoded HS-SCCH and HS-DSCH are decoded, thereby reducing unnecessary decoding work.

For example, when the terminal decodes the HS-SCCH and the HS-DSCH, and a transmission gap occurs to transmit a HS-DPCCH signal, that is, an ACK / NACK signal for the HS-DSCH, to the base station, the base station transmits the HS. Since the ACK / NACK signal for the SCCH and the HS-DSCH has not been received, the previously transmitted HS-SCCH and HS-DSCH are retransmitted.

Meanwhile, the terminal receiving the new HS-SCCH checks a HARQ process ID from the HS-SCCH and checks a new data indicator. When the check result indicates that the HS-DSCH associated with the HS-SCCH is new data, the HS-DSCH is subsequently decoded regardless of normal demodulation of the previous HS-DSCH. However, when the new data identifier indicates continuous data, the previously decoded result of the HS-DSCH corresponding to the corresponding process ID is checked. The demodulation of the newly received HS-DSCH is determined according to normal demodulation of the previously received corresponding HS-DSCH. That is, when the decoding result of the previously received corresponding HS-DSCH is ACK, the newly received HS-DSCH is already decoded, and thus it is not necessary to decode the packet. If the decoding result is NACK, the newly received HS-DSCH is not received. Since the HS-DSCH is a packet that was not normally decoded, after decoding, the HS-DSCH is combined with previously decoded packets.

Hereinafter, the above-described procedure according to the second embodiment of the present invention will be described in more detail with reference to FIG. 9.

9 is a flowchart illustrating a decoding procedure of the HS-DSCH in the HSDPA scheme according to the second embodiment of the present invention.

Referring to FIG. 9, when the ACK / NACK signal of the uplink HS-DPCCH is not normally transmitted as described above, the terminal subsequently receives a new data identifier of the newly received HS-SCCH and an ACK of the previously received HS-DSCH. It is determined whether the HS-DSCH is demodulated according to / NACK. In other words, it is assumed that there is no error in the information of the corresponding ACK / NACK transmitted through the HS-DPCCH, or that the ACK / NACK information of the HS-DPCCH is not transmitted due to a transmission gap.

First, when the transmission space is over and the terminal receives a new HS-SCCH signal, to determine the HARQ processing identifier of the HS-SCCH for normal HARQ processing (910). In addition, the new data indicator (new data indicator) of the decoding result of the HS-SCCH is confirmed (920). If the new data identifier indicates 'new data' (930), the HS-DSCH transmitted after the associated with the HS-SCCH is normally decoded, and the HARQ is newly operated (940).

Meanwhile, if the new data identifier indicates 'continuing data', the decoding result of the HS-DSCH corresponding to the previously received corresponding processing identifier is checked (950). The ACK / NACK information, which is the decoding result of the HS-DSCH, is not transmitted to the base station by the transmission gap as described above, but the terminal stores the ACK / NACK information.

If the decoding result of the previously received HS-DSCH is ACK (960), the newly received HS-DSCH associated with the HS-SCCH is a packet that is normally decoded, and thus no longer need to be decoded unnecessarily. . Therefore, the corresponding HS-DSCH received afterwards does not perform decoding (980).

On the contrary, if the decoding result of the previously received HS-DSCH is NACK (960), the newly received HS-DSCH associated with the HS-SCCH is a packet that cannot be decoded normally and must be decoded. Combination is performed (970).

According to the above method, even if ACK / NACK information is not transmitted from the terminal and thus retransmission is performed in the base station, the terminal may not perform unnecessary demodulation and decoding operations or may further improve the HARQ combining effect.

<Third Embodiment-Case of Considering Uplink Effect on Downlink>

Hereinafter, a method according to a third embodiment of the present invention will be described with reference to FIG. 8.

FIG. 8 is a diagram illustrating a time relationship when ACK / NACK information cannot be transmitted due to an uplink transmission gap in the HSDPA scheme according to the third embodiment of the present invention.

Referring to FIG. 8, it may be determined whether demodulation of the HS-SCCH associated with the previously received HS-DPCCH is considered in consideration of the position of the ACK / NACK field of the uplink HS-DPCCH.

According to the third embodiment of the present invention, the ACK / NACK field of the uplink HS-DPCCH may not be transmitted according to the transmission gap of the uplink DPCH. In this case, the HS-SCCH associated with the HS-DPCCH is first displayed. You can avoid demodulation. That is, since the HS-SCCH associated with the uplink HS-DPCCH is transmitted and received at a predetermined time interval (for example, 13.5 slots), when the HS-DPCCH corresponds to a transmission gap, the HS-SCCH associated with the HS-DPCCH is determined. Methods to avoid demodulation may be considered.

In more detail, the above-described method determines whether demodulation of downlink is performed in consideration of the effect on uplink, and thus, calculates a time interval from a time point at which transmission gap of uplink starts as shown in FIG. 8. do. Do not perform decoding on the HS-SCCH received for a length of the transmission gap from after a time before 13.5 slot from the slot where the transmission gap of the uplink starts. Likewise, the HS-DSCH may take appropriate measures so as not to perform decoding.

For example, a signal called the compression mode period COMP_MODE described above in the first embodiment may be used. In addition, it is also possible to use a method in consideration of the influence of the downlink and a method in consideration of the influence of the uplink in the first embodiment.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention can reduce the power consumption of the terminal by preventing unnecessary demodulation without additional hardware or software increase while satisfying the conditions set forth in the standard in the terminal supporting HSDPA in the compression mode. There is an advantage.

In addition, when the decoding of the HS-DSCH is performed, but the ACK / NACK portion of the uplink HS-DPCCH overlaps with the transmission gap, the ACK / NACK information cannot be transmitted. (Combing) effect can be obtained, and unnecessary demodulation and decoding of HS-DSCH may not be performed.

Considering that the compression mode occupies 20% to 30% of the total work of the UMTS system, the power reduction effect according to the present invention is considerably large.

Claims (13)

A method for demodulating high speed forward packet data in a mobile communication system to which a compression mode for measuring power of a cell using a different frequency band is applied, Calculating a time point before a predetermined time interval from a start time point of a transmission gap; And not demodulating a high speed forward common control channel (HS-SCCH) signal received from the calculated time. The method of claim 1, And the predetermined predetermined time interval is 5 slots. The method of claim 1, And not demodulating a high speed forward common channel (HS-DSCH) signal associated with the high speed forward common control channel (HS-SCCH) received from the calculated time. The method of claim 1, The calculation of a time point before a predetermined time interval from the start time of the transmission gap uses time information regarding a time offset and a compression mode of a downlink dedicated physical channel (DPCH) and the fast forward common control channel (HS-SCCH). The method characterized in that the calculation. A method for demodulating high speed forward packet data in a mobile communication system to which a compression mode for measuring power of a cell using a different frequency band is applied, Identifying a new data indicator of a newly received fast forward common control channel; Determining whether to demodulate a high-speed forward common channel (HS-DSCH) signal received after considering the normal demodulation of the identified new data indicator and the previously received high-speed forward common channel (HS-DSCH). Characterized in that the method. The method of claim 5, Determining whether to demodulate the HS-SCCH signal received after considering the normal demodulation of the confirmed new data indicator and the previously received HS-DSCH. The method characterized in that. The method of claim 5, And when the confirmed new data indicator indicates new data, the high-speed forward common channel (HS-DSCH) signal received thereafter is normally demodulated. The method of claim 5, The new data indicator indicates that the identified new data indicator is continuous data. When the previously received high speed forward common channel (HS-DSCH) is normally demodulated, the received high speed forward common channel (HS-DSCH) signal is processed without demodulation. The method characterized in that. The method of claim 5, The confirmed new data indicator indicates that the continuous data, and if the previously received high-speed forward common channel (HS-DSCH) is not normally demodulated, the received high-speed forward common channel (HS-DSCH) signal is normally demodulated, The demodulated packets are combined with a HARQ scheme. A method for demodulating high speed forward packet data in a mobile communication system to which a compression mode for measuring power of a cell using a different frequency band is applied, Calculating a time point before a predetermined time interval from a start time point of a transmission gap; And processing a high speed forward common control channel (HS-SCCH) signal received from the calculated time without demodulation. The method of claim 10, The preset predetermined time interval is 13.5 slots. The method of claim 10, And processing a high speed forward common channel (HS-DSCH) signal associated with the high speed forward common control channel (HS-SCCH) received from the calculated time without demodulation. The method of claim 10, The calculation of a time point before a predetermined time interval from the start time of the transmission gap uses time information regarding a time offset and a compression mode of a downlink dedicated physical channel (DPCH) and the fast forward common control channel (HS-SCCH). The method characterized in that the calculation.