KR20030080165A - Transmit Power control method for High Speed Downlink Packet Access system - Google Patents

Abstract

PURPOSE: A method for controlling transport power of an HSDPA(High Speed Downlink Packet Access) system is provided to supply a power control system of a downlink HS-SCCH(Shared Control Channel) using a channel quality indicator, thereby performing HS-SCCH power control. CONSTITUTION: A base station receives CQIs(Channel Quality Indicators) reported every sub frame(S200). The base station extracts a CPICH(Common Pilot Channel) SIR value measured by a UE(User Element) from the received CQIs(S202). The base station calculates HS-SCCH output power from the CPICH SIR value(S202), and adds a power margin to the calculated HS-SCCH output control. The base station finally calculates HS-SCCH output power(S206).

Description

Transmit power control method for High Speed Downlink Packet Access system

The present invention relates to a 3GPP UMTS system, and more particularly, to a transmission power control method of a common control channel according to a common control channel measurement report of a downlink channel of a high speed downlink packet access (HSDPA) system.

UMTS (Universal Mobile Terrestrial System) is a third generation mobile communication system that has evolved from the European standard Global System for Mobile Communications (GSM) system.It is based on GSM Core Network and Wideband Code Division Multiple Access (WCDMA) access technology. In order to provide a more improved mobile communication service. For the standardization of UMTS, in December 1998, ETSI in Europe, ARIB / TTC in Japan, T1 in the US and TTA in Korea were referred to as the Third Generation Partnership Project (hereinafter abbreviated as 3GPP). The project has been organized and is currently developing a detailed specification of UMTS.

In 3GPP, UMTS standardization work is divided into 5 Technical Specification Groups (abbreviated as TSG) in consideration of the independence of network components and their operation for the rapid and efficient technology development of UMTS. I'm going. Each TSG is responsible for the development, approval, and management of standards within the relevant areas, among which the Radio Access Network (hereinafter referred to as RAN) group (TSG-RAN) supports WCDMA access technology in UMTS. To develop a specification for the function, requirements high speed, and interface of the UMTS radio network (Universal Mobile Telecommunications Network Terrestrial Radio Access Network, hereinafter referred to as UTRAN).

The TSG-RAN Group is again composed of a Plenary Group and four Working Groups. Working Group 1 (WG1) develops standards for the Physical Layer (WG1), while the second Working Group (WG2) works with the Data Link Layer (2nd Layer) and Network Layer (WG2). Role of the third tier). In addition, the third operation group defines standards for interfaces between base stations, radio network controllers (hereinafter referred to as RNCs) and core networks in the UTRAN, and the fourth operation group relates to radio link performance. Discuss requirements and requirements for radio resource management.

1 is a diagram showing the structure of a 3GPP UTRAN to which the prior art and the present invention is applied.

Referring to FIG. 1, the UTRAN 110 includes one or more Radio Network Sub-systems (hereinafter referred to as RNS) 120 and 130, and each RNS 120 and 130 is connected to one RNC 121 and 131. It consists of one or more base stations (NodeBs) 122, 123, 132, 133 managed by the RNCs 121, 131. The RNCs 121 and 131 are connected to a mobile switching center (MSC) 141 for circuit-switched communication with a GSM network, and SGSN (for packet-switched communication with a general packet radio service (GPRS) network). Serving GPRS Support Node) 142.

The base station (Node B) 122, 123, 132, 133 is managed by the RNC (121, 131), and receives the information sent from the physical layer of the terminal 150 in the uplink, and the terminal 150 in the downlink It serves as an access point of the UTRAN to the terminal transmitting to. The RNCs 121 and 131 are in charge of allocating and managing radio resources. The RNC, which is responsible for the direct management of the base station Node B, is called a control RNC (CRNC), and is in charge of managing a common radio resource. A place that manages dedicated radio resources allocated to each terminal is called a serving RNC (SRNC). The control RNC and the responsible RNC may be the same, but when the terminal moves out of the area of the responsible RNC to the area of another RNC, the control RNC and the responsible RNC may be different. The various components in the UMTS network can be in different locations, so an interface is needed to connect them. The base station Node B and the RNC are connected by an Iub interface, and the RNC is connected through an Iur interface. The interface between the RNC and the core network is called Iu.

2 illustrates a structure of a radio access interface protocol between a terminal and a UTRAN based on the 3GPP radio access network standard. The wireless access interface protocol of FIG. 2 consists of a physical layer (PHY), a data link layer, and a network layer horizontally, and vertically transmits a control plane for transmitting control signals and data information transmission. It is divided into user planes. The user plane is an area in which user traffic information is transmitted, such as voice or IP packet transmission, and the control plane is an area in which control information is transmitted, such as network interface or call maintenance and management.

The protocol layers of FIG. 2 are based on the lower three layers of the Open System Interface (OSI) reference model, which are well known in communication systems. The first layer (L1), the second layer (L2), and the third layer (L3).

The first layer L1 performs a role of a physical layer (PHY) for the wireless interface, and a transport channel with a medium access control layer (hereinafter abbreviated as MAC) layer on the upper layer. Are connected via Data transmitted to the physical layer through a transport channel is transmitted to a receiver by using various coding and modulation methods suitable for a wireless environment. The transport channel existing between the physical layer and the MAC layer is a dedicated transport channel and a common transport channel, respectively, depending on whether the terminal can be used exclusively or shared by multiple terminals. Are distinguished.

The second layer L2 serves as a data link layer, and allows multiple terminals to share radio resources of the WCDMA network. The second layer (L2) is the MAC layer, Radio Link Control (hereinafter referred to as RLC) layer, Packet Data Convergence Protocol (hereinafter referred to as PDCP) layer, and broadcast / multicast control (Broadcast / Multicast Control; hereinafter abbreviated as BMC) is divided into layers.

Here, the MAC layer transfers data through an appropriate mapping relationship between logical channels and transport channels. Logical channels are provided with various logical channels according to the type of information transmitted to the channels connecting the upper layer and the MAC layer. In general, a control channel is used to transmit control plane information, and a traffic channel is used to transmit information of the user plane. The MAC layer is divided into two sublayers according to the function performed again. These are the MAC-d sublayer located in the SRNC while managing the dedicated transport channel, and the MAC-c / sh sublayer located in the CRNC while managing the shared transport channel.

The RLC layer configures an appropriate RLC PDU suitable for transmission by a segmentation and concatenation function of an RLC SDU transmitted from an upper layer, and performs an automatic repeat request for retransmitting an RLC PDU lost during transmission. ARQ) function can be performed. The RLC SDU or RLC descended from the upper layer operates in three ways: transparent mode, unacknowledged mode, and acknowledgment mode, depending on the method of processing the RLC SDU from the upper layer. There is an RLC buffer for storing PDUs.

The PDCP layer is located on top of the RLC layer and makes data transmitted through a network protocol such as IPv4 or IPv6 suitable for transmission in the RLC layer. In particular, a header compression technique that compresses and transmits header information of a packet may be used for efficient transmission of an IP packet.

The BMC layer enables a message transmitted from a cell broadcast center (CBS) to be transmitted through an air interface. The main function of the BMC is to schedule and transmit a cell broadcast message transmitted to a terminal, and generally transmits data through an RLC layer operating in an unresponsive mode.

For reference, since the PDCP layer and the BMC layer use a packet switching scheme, the PDCP layer and the BMC layer are connected to the SGSN and are only located in the user plane because only user data is transmitted. Unlike these, the RLC layer may belong to the user plane or to the control plane depending on the layers connected to the upper layer. In case of belonging to the control plane, it corresponds to a case of receiving data from a radio resource control layer (hereinafter, referred to as RRC) layer, and otherwise corresponds to a user plane. In general, a service of transmitting user data provided to the upper layer by the second layer L2 in the user plane is defined as a radio bearer (RB), and the upper layer by the second layer L2 in the control plane. The transmission service of the control information provided by is defined as a signaling radio bearer (SRB). In addition, as shown in FIG. 2, in the case of the RLC layer and the PDCP layer, several entities may exist in one layer. This is because one terminal has several radio carriers, and generally only one RLC entity and PDCP entity are used for one radio carrier. Entities of the RLC layer and the PDCP layer may perform independent functions in each layer.

The RRC layer located at the bottom of the third layer L3 is defined only in the control plane, and is responsible for control of transport channels and physical channels in connection with setting, resetting, and releasing radio carriers. In this case, the setting of the wireless carrier means a process of defining characteristics of a protocol layer and a channel necessary to provide a specific service and setting each specific parameter and operation method. It is also possible to transmit control messages transmitted from a higher layer through an RRC message.

The WCDMA system described above aims at a transmission rate of 2Mbps in a indoor and pico-cell environment and 384kbps in a general wireless environment. However, as the wireless Internet is becoming more common and the number of subscribers is increasing, more various services are emerging, and higher speeds are required to support them. Therefore, in 3GPP, a research is being conducted to provide a high transmission speed by evolving a WCDMA network, and a representative system is HSDPA (High Speed Downlink Packet Access).

Based on WCDMA, the HSDPA system can support up to 8-10Mbps in downlink, and can provide shorter latency and improved capacity. The techniques employed in the HSDPA system to provide improved transmission rates and capacities include Link Adaptation (LA), Hybrid Automatic Repeat Request (HARQ), and fast cell selection. Fast Cell Selection (hereinafter referred to as FCS), and Multiple Input Multiple Output (hereinafter referred to as MIMO) antenna techniques.

The link adaptation technique (LA) uses a modulation and coding scheme (hereinafter referred to as MCS) that is adapted to the state of the channel. If the channel state is good, a high modulation such as 16QAM and 64QAM is used. In case the channel condition is not good, a low modulation method such as QPSK is used.

In general, the low-modulation method has a smaller amount of transmission than the high-modulation method, but it shows excellent transmission success rate when the channel environment is not good. Therefore, it may be considered to be advantageous when the influence of fading or interference is large. . On the other hand, high modulation methods have much higher frequency utilization efficiency than low modulation methods, and can provide a transmission rate of 10Mbps using the 5MHz bandwidth of WCDMA. However, it is very sensitive to the effects of noise and interference. Therefore, when the terminal is located close to the base station, it is possible to increase the transmission efficiency by using 16QAM or 64QAM, and when the terminal is located at the cell boundary or the influence of fading is low, a low modulation method such as QPSK is useful. Do.

The HARQ method is a retransmission method having a different concept from that of a packet retransmission performed in the RLC layer. This ensures higher decoding success rates by combining data used and retransmitted in conjunction with the physical layer with previously received data. In other words, it is a method of decoding by combining the retransmitted packet with the previous step of decoding while storing the packet which failed to be transmitted without discarding it. Therefore, when used together with the LA technique, the packet transmission efficiency can be greatly increased.

The FCS method is similar to the conventional soft handover. Although the terminal may receive data from multiple cells, the terminal may receive data from a cell having the best channel state in consideration of the channel state of each cell. Conventional soft handover has been a method of receiving data from multiple cells and increasing the transmission success rate using diversity, but the FCS method receives data from only one specific cell in order to reduce interference between cells.

MIMO antenna technique is a method that can improve the data transmission speed by using several independent channels in a channel environment where scattering is high. It is a system that is composed of several transmitting antennas and several receiving antennas to obtain diversity gain by reducing the correlation between radio waves received for each antenna.

Meanwhile, the HSDPA system is based on the existing WCDMA network and tries to introduce a new technology while keeping the WCDMA network as it is. However, some modifications are inevitable to incorporate new technologies. Representatively, the example is an improvement of the existing base station (Node B) function. That is, in the WCDMA network, most of the control functions are located in the RNC, but most of the new technologies for the HSDPA system are managed by the base station (Node B) in order to adapt to the channel situation more quickly and reduce the delay time to the RNC. However, the extended function of the base station (Node B) is not a function of replacing the RNC, and from the standpoint of the RNC, it can be seen that the functions for the high speed data transmission are in charge of the auxiliary function added.

Therefore, unlike the existing WCDMA system, the base station Node B has been modified to perform a part of the MAC function, and a layer for performing this is called a MAC-hs sublayer.

The MAC-hs sublayer may be located above the physical layer to perform packet scheduling or HARQ and LA functions. In addition, a transport channel called HS-DSCH (High-Speed Downlink Shared Channel), which is different from the existing transport channel, is used for data transmission for HSDPA. This channel is used to transmit data from the MAC-hs sublayer of the base station Node B to the physical layer.

The HS-DSCH has a short transmission time interval (TTI) (3 slots, 2 ms) unlike the R'99 / R'4, which is a conventional W-CDMA system. Modulation code set (MCS) is supported, and optimal throughput can be raised by selecting the MCS that is most suitable for the channel situation.

To this end, hybrid ARQ (HARQ) technology, which combines automatic repeat request (ARQ) technology and channel coding technology, ensures reliable transmission and uses code division multiplexing (CDM). It is proposed to support up to four users at the same time. The physical channel corresponding to the transport channel HS-DSCH is the same as before.

As described above, control information is required for HS-DSCH, and the information is transmitted through a shared control channel (HS-SCCH) introduced in the HSDPA standard.

For reference, Release 1 and Release 2 are the standard versions of Global System for Mobile Communication (GSM) respectively, and R'99 is the standard version of 3GPP, which stands for Release 1999 (released in March 2000). , Same as Release 3). R4 also refers to the standard version of 3GPP, which is an acronym for Release 4 (released March 2001, same as Release 2000). Release 5 is also the version that is currently being standardized.

A physical channel corresponding to the transport channel HS-DSCH is described below.

The 3GPP system supports high packet data services in downlink with HS-DSCH transmission.

To this end, a new structure of a transport channel called HS-DSCH and control signaling for it have been proposed.

3 illustrates a subframe and slot structure of a physical channel HS-PDSCH to which an HS-DSCH is mapped. The HS-PDSCH is transmitted in one or multiple SF = 16 codes. The HS-DSCH subframe consists of three slots. The HS-PDSCH channel transmits QPSK or 16 QAM modulation symbols. In Figure 3, M refers to the number of bits per modulation symbol. That is, when QPSK, M = 2 and M = 4 when 16 QAM. This HS-PDSCH transmits only user data.

Table 1 shows slot format information of the HS-PDSCH field.

As described above, transmission of control information is required for transmission of user data through the HS-DSCH, and the information includes a downlink shared control channel (HS-SCCH) and an uplink HS, which are introduced in the HSDPA standard. It is transmitted through DPCCH (High SpeedDedicated Physical Control Channel). That is, in order to service the HSDPA, an HS-DPCCH is required on the uplink in addition to the conventional uplink DPCCH. The HS-DPCCH includes such things as HARQ-ACK and CQI information. The uplink DPCCH includes TPC, Pilot, TFCI, and FBI information as in the case of the non-HSDPA system.

Control information transmitted on the downlink shared control channel can be roughly divided into TFRI (Transport Format and Resource related Information) and HARQ related information. The TFRI includes information about an HS-DSCH transport channel set size, a modulation method, a coding rate, and a number of multicodes. HARQ-related information includes a block number, Information such as redundancy version is included. In addition, information about a mobile station identifier (UE Id) is transmitted to indicate which user's information. The information related to the mobile station identifier performs a CRC operation together with the TFRI and HARQ information to transmit only the resulting CRC.

The surf frame structure of the downlink shared control channel (HS-DSCH) for transmitting downlink control information is shown in FIG. One time slot consists of 2560 chips and consists of 40 bits.

5 shows a frame structure of an uplink HS-DPCCH.

5, the uplink HS-DPCCH transmits uplink feedback signaling associated with downlink HS-DSCH data transmission. Feedback signaling is composed of ACK (Acknowledgement) / NACK (Negative Acknowledgement) information for mixed ARQ and Channel Quality Indicator (CQI).

The frame of the HS-DPCCH is divided into five subframes of 2ms in length, and one surf frame is composed of three slots. ACK / NACK information for mixed ARQ is transmitted in the first slot of the HS-DPCCH subframe, and CQI is transmitted in the second and third slots of the HS-DSCH subframe. The HS-DPCCH is always transmitted with the uplink DPCCH. The CQI transmits the TFRI value calculated from the state information or the state information of the downlink radio channel obtained from the mobile station's measurement of the downlink Common Pilot Channel (CPICH), and the ACK / NACK is the downlink HS by the Hybrid ARQ mechanism. Informs the ACK or NACK information on the transmission of the user data packet transmitted to the DSCH.

FIG. 6 illustrates signaling of a downlink shared control channel (HS-SCCH) for transmitting downlink control information. As shown in the figure, multiple users can be supported at the same time, and control information for this uses a shared control channel allocated to each user. The maximum user that can be supported is M = 4.

Power control of this common control channel is performed according to a TPC command sent on the uplink DPCCH. That is, the HS-SCCH output power is adjusted to a power offset value relative to the output power of the downlink DPCCH channel adjusted according to the TPC command transmitted on the uplink.

However, HSDPA's HS-SCCH is transmitted only in one cell even during soft handover (SHO), while uplink transmit power control (TPC) combines downlink channels transmitted in all cells involved in soft handover. Since it is calculated and transmitted for power, it is problematic to use TPC for HS-SCCH power control during soft handover. Normally, this is compensated for by setting more power offsets during soft handover. However, when only transmission power control is used, the HS-SCCH transmission power takes a large part of the total power of the base station during soft handover.

An object of the present invention is to enable a base station to periodically control the transmission power of a common control channel by using information obtained by measuring state information of a downlink radio channel from a mobile station.

Another feature of the present invention is to enable the transmission power of a common control channel to be controlled using a period in which a CQI is reported to a base station or some period in which a CQI is reported.

It is another object of the present invention to use the uplink TPC in addition to the common control channel transmission power setting method using the CQI, to control the transmission power of the common control channel by the two methods.

Another feature of the present invention is to distinguish between soft handovers of mobile stations and to apply different power control schemes to common control channels.

Another object of the present invention is to compare the transmission power of a common control channel required by a mobile station with a set threshold, and to apply a power control method using a CQI and a power control method using a TPC according to a threshold value. .

1 is a structure of the UTRAN of the 3GPP system.

2 is a structure of a radio access interface protocol of a 3GPP system.

3 is a subframe structure of HS-PDSCH in a high speed downlink packet access system.

4 is a subframe structure of HS-SCCH in a high speed downlink packet access system.

5 is a frame structure of the uplink HS-DPCCH of the HSDPA system in the high speed downlink packet access system.

6 illustrates an example of a shareable user of a downlink control channel.

7 is a flowchart illustrating a transmission power control method using CQI according to the first embodiment of the present invention.

8 is a flowchart illustrating a transmission power control method using CQI according to another embodiment of the present invention.

9 is a flow chart of applying a power control method using an uplink TPC to a power control method using a CQI according to a second embodiment of the present invention.

10 is a flowchart illustrating different power control schemes depending on whether soft handover is performed according to a third embodiment of the present invention.

11 is a flowchart showing an example of a third embodiment according to the present invention;

12 is a flowchart showing another example of the third embodiment according to the present invention;

13 is a flowchart illustrating a power control method using CQI and TPC by HS-SCCH transmission power according to a fourth embodiment of the present invention.

The downlink transmission power control method of the high speed downlink packet access system according to the present invention for achieving the above object,

Extracting an SIR value of a CPICH channel using channel measurement information reported by the mobile station;

Calculating an HS-SCCH output power from the CPICH SIR value;

And adding a power margin to the calculated HS-SCCH output power to final calculate the HS-SCCH output power.

Preferably, the channel measurement information is characterized in that the channel quality indicator.

Preferably, the SIR value of the CPICH is characterized in that the transmission power value is changed by extracting according to the period in which the channel measurement information is reported.

Preferably, the channel measurement information is characterized by using one channel quality indicator for each period in which the channel quality indicator is reported.

Preferably, the channel measurement information is characterized by deriving an HS-SCCH transmission power value using a value obtained by averaging a plurality of channel measurement information reported once every predetermined subframe.

A transmission power control method of a high speed downlink packet access system according to the present invention includes: calculating HS-SCCH output power of a specific slot every predetermined period using CQI information of a previous subframe; After increasing the time slot, determining, according to the power increase / decrease command of the uplink transmission power control, the power of the next slot with the power increased or decreased by a gain corresponding to the power of the current slot.

Specifically, the HS-SCCH output power determination of the slot is characterized in that the output power control using the CQI is performed in subframe units, and the output power control using the uplink transmission power control is performed in slot units in the subframe. .

A transmission power control method of a high speed downlink packet access system according to the present invention includes: performing power control of an HS-SCCH using uplink transmission power control; Detecting whether a specific mobile station is in soft handover, and then switching to power control of the HS-SCCH of the mobile station by using channel measurement information of a predetermined period reported by the mobile station when in a soft handover state; If it is not the soft handover, characterized in that it comprises the step of performing the power control using the TPC.

The transmission power control method of the high speed downlink packet access system according to the present invention comprises the steps of: power control of the HS-SCCH using the channel measurement information, using the channel measurement information reported by the mobile station, extracting an SIR value of a CPICH channel; Calculating an HS-SCCH output power from the CPICH SIR value; And adding a power margin to the calculated HS-SCCH output power to final calculate the HS-SCCH output power.

According to another aspect of the present invention, there is provided a transmission power control method of a high speed downlink packet access system, including: performing HS-SCCH power control using uplink transmission power control; Receiving configuration information of radio link radio links set for the mobile station from the radio network controller, and then checking whether the mobile station has a soft handover state or whether a radio link has been added; Receiving a CQI reported for each subframe of a certain period when there is soft handover or addition of a radio link as a result of the checking; Extracting the CPICH SIR value measured by the mobile station from the reported CQI, and then calculating the HS-SCCH output power; And adding a power margin to the calculated HS-SCCH output control to finally calculate the HS-SCCH output power.

According to another aspect of the present invention, there is provided a transmission power control method of a high speed downlink packet access system, the wireless network controller instructing a base station of a power control type of a mobile station; And switching to a corresponding power control of the HS-SCCH according to a method corresponding to the power control type, and performing power control.

According to another aspect of the present invention, there is provided a transmission power control method of a high speed downlink packet access system, comprising: performing transmission power control of an HS-SCCH using an uplink TPC; Detecting the required power of the HS-SCCH of the corresponding mobile station by a required power value of the radio network controller or an internal measurement of the base station, and then switching to and performing power control using the CQI if the detected required power is greater than or equal to a threshold; And switching to and performing power control using a TPC when the detected HS-SCCH required power is less than or equal to a threshold.

The downlink transmission power control method of the high speed downlink packet access system according to the present invention as described above is as follows.

Since the channel quality indicator (CQI) reported by the mobile station is channel measurement information for only the downlink channel of the cell transmitting the HS-SCCH, it can give more accurate information in controlling the power of the HS-SCCH. Accordingly, the present invention proposes a power control scheme of the downlink HS-SCCH using channel measurement information transmitted through the uplink HS-DPCCH in addition to the uplink TPC, that is, the channel quality indicator (CQI).

At this time, the CQI is the state information of the downlink radio channel. The CQI is mainly generated from information measured by the power of the downlink CPICH, and periodically reports the information to the base station through the uplink HS-DPCCH channel according to the setting of the radio network. Say. CQI is transmitted once every k subframes.

The power control method using the CQI and the power control method using the TPC may be selectively performed when certain conditions are satisfied, or may be performed when an instruction is directed from a higher level to a specific power control method.

When described in detail with reference to the embodiments as follows.

First embodiment;

The first embodiment is an HS-SCCH transmission power setting method using CQI, which will be described in detail with reference to FIGS. 7 and 8 as follows.

FIG. 7 is a flowchart for calculating an HS-SCCH output power using CQI every k subframes. First, a base station receives a CQI reported every k subframes (S200), and receives a mobile station (UE) from the received CQI. The measured CPICH SIR value is extracted (S202).

After calculating the HS-SCCH output power from the CPICH SIR value (S202), the power margin is added to the calculated HS-SCCH output control to finally calculate the HS-SCCH output power (S206).

8 is a flowchart for calculating an HS-SCCH output power using several CQIs. First, a base station receives a CQI reported every k subframes (S210), and a mobile station from a plurality of CQIs reported every M subframes. The measured CPICH SIR value is extracted (S212). At this time, after calculating the HS-SCCH output power from the CPICH SIR value (S214), the HS-SCCH output power is finally calculated by adding a power margin to the calculated HS-SCCH output power (S216).

As such, the base station derives the HS-SCCH transmit power value from the CQI information. In order to derive the HS-SCCH transmission power value from the CQI information, the CQI information reported for each subframe is received, and the SIR value of the CPICH channel measured by the mobile station (UE) is extracted from the received CQI information. Then, the required HS-SCCH output power is first calculated from the CPICH SIR value, and then the power margin is added to the calculated HS-SCCH output control to finally calculate the HS-SCCH output power. In this case, the HS-SCCH transmit power value transmitted by the actual base station is determined by adding a margin considering the error of measurement and calculation to the calculated requested HS-SCCH transmit power value.

This method is subdivided into two types according to the period in which the base station changes the HS-SCCH transmit power value.

First, as shown in FIG. 7, the base station calculates an HS-SCCH transmit power value from one CQI information once every k subframes, which is a period in which the CQI is reported. Therefore, the HS-SCCH transmit power value is changed once every k subframes.

Second, as shown in FIG. 8, the HS-SCCH transmit power value is derived from the result of averaging the CQI information received during the M subframes. Therefore, the HS-SCCH transmit power value is changed once every M subframes. At this time, in order to derive the transmission power value from the average result of the CQI information, M corresponds to an integer greater than k. If M = k, the second scheme is the same as the first scheme.

Here, the transmission power does not change between cycles of changing the transmission power.

Second embodiment;

In the second embodiment, the uplink TPC is additionally used for the HS-SCCH transmission power setting method using the CQI. As shown in FIG. 9, the HS-SCCH transmission power value is determined using the CQI method and the TPC method. It is to induce.

Referring to FIG. 9, the base station receives a reported CQI in a certain subframe (F = k or M) (S220), and calculates a CPICH SIR value measured by the mobile station for every k or M subframes from the reported CQI for each subframe. Extract (S221), and calculate the HS-SCCH output power from the CPICH SIR value (S222). Where k is the period in which CQI is reported and M is an integer greater than k.

The HS-SCCH output power of the n-th slot is calculated by adding a power margin to the calculated HS-SCCH output (S223). n is any positive integer.

At this time, the value of the counter t is set to 1 (that is, t = 1) (S224), and the gain calculated for the power of the current slot n + t-1 according to the power up / down command of the uplink TPC. Increasing or decreasing (S225), the power of the next slot is determined by the increased or decreased power (S226).

Thereafter, the counter value of the slot is compared with a value equal to the value of the predetermined number of subframes (F) multiplied by 3 (S227), and if it is the same, the counter value is increased (t = t + 1) to perform step S225. If it is small, the counter value is added to the slot (n = n + t) to perform power control for the next slot (S229). That is, since F is a previous k or M subframe, the HS-SCCH transmit power of the n + (3 × k) or n + (3 × M) slot is determined using the CQI information during the k or M subframe.

Therefore, the base station determines the transmit power of the HS-SCCH in the same manner as S225, S226 during n + (3 x k) -1 or n + (3 x M) -1 slots in n + 2, and In the same way, the HS-SCCH transmit power of the n + (3 xk) or n + (3 x M) slots is determined using the CQI information during the previous k or M subframe.

This second embodiment takes into account the channel change during the period of changing the HS-SCCH transmit power. That is, between the time points at which the HS-SCCH transmit power is changed by the CQI, the base station raises or lowers the transmit power according to the uplink TPC information.

Third embodiment;

The third embodiment uses different power control schemes by classifying soft handover, which will be described with reference to FIGS. 10 to 12.

10 is a flow chart illustrating different power control by dividing soft handover according to an exemplary embodiment of the present invention.

Referring to FIG. 10, the base station first performs power control using a TPC (S2300), and then checks whether the corresponding mobile station is in a soft handover (SHO) state (S232).

In this case, when the mobile station is in a soft handover situation, the UE receives a CQI reported every predetermined subframe (k, M) (S234), extracts the CPICH SIR value therefrom (S236), and then primarily calculates the HS-SCCH output power. After the calculation (S238), the final margin is added to the calculated HS-SCCH output power to finally calculate the HS-SCCH output power (S240).

As a result of the S232 check, if the mobile station does not have a soft handover situation, the mobile station performs power control using a conventional TPC (S230).

The third embodiment applies the power control method using the CQI as in the first embodiment only when in the soft handover situation, and the HS-SCCH power control method using the TPC only when the soft handover is not applied. Can be. Accordingly, when the mobile station enters the soft handover area, the base station switches to the power control method using the CQI, and when the mobile station enters the soft handover area, the base station switches to the power control method using the TPC.

As described above, in the method of classifying soft handover, first, when performing power control using a TPC as shown in FIG. 11 (S250), the RNC receives information on whether the mobile station has a soft handover or a radio link set to the mobile station. After that (S252), it is checked whether the soft handover state of the corresponding mobile station or the radio link is added from the received radio link information (S254).

At this time, if a soft handover state or a radio link of the mobile station is newly added, the base station calculates the HS-SCCH output power using the CQI in the same manner as in the first embodiment (S256 to S262).

In this case, when the corresponding mobile station is not in the handover state or the number of radio links is switched to 1, power control using a conventional TPC is performed (S264).

Second, as shown in FIG. 12, while the base station performs power control using a TPC (S270), after receiving an HS-SCCH power control method change instruction command from the RNC, and if the power control instruction command using the CQI, the CQI. Switch to and control the power control using (S272, S274), if the power control command command using the TPC continues to perform the power control using the TPC (S276).

Fourth embodiment;

In the fourth embodiment, a threshold for comparing with the HS-SCCH transmit power required by the mobile station is set, and the HS-SCCH output power is controlled by applying the transmit power control using the CQI and the power control control method using the TPC according to the threshold. I would have to.

Referring to FIG. 13, the base station performs power control using a TPC (S280), and the wireless network controller is required as a result of transmitting a power value required for the HS-SCCH to the base station or deriving it from the internal measurement value of the base station. The HS-SCCH transmit power is determined (S282). At this time, after confirming whether the HS-SCCH transmit power required for the mobile station is greater than or equal to the threshold set by the base station (S284), if it is greater than or equal to the threshold, the controller switches and performs power control using CQI (S286). The used power control is performed (S280). That is, when the required HS-SCCH transmission power is less than or equal to the threshold set by the base station, the HS-SCCH power control method using only the TPC is applied.

As described above, according to the transmission power control method of the high speed downlink packet access system according to the present invention, in addition to the uplink TPC, channel measurement information transmitted through the uplink HS-DPCCH, that is, downlink HS- using the channel quality indicator By providing the power control scheme of the SCCH, the base station performs the HS-SCCH power control in response to the change in the radio channel more appropriately, thereby reducing the base station power allocated to the HS-SCCH.

Claims (18)

A mobile communication base station having a downlink shared control channel shared by a plurality of terminals, Receiving channel state measurement information for a downlink channel wirelessly connected to the base station and the terminal from the terminal; Calculating an output power of a downlink shared control channel from the channel state measurement information; Transmitting a signal through the downlink shared control channel at the calculated output power. The method of claim 1, And the channel state measurement information is a channel quality indicator. The method of claim 2, The calculating of the output power of the downlink shared control channel may be performed using a value obtained by averaging a plurality of channel quality indicators reported at predetermined periods. The method of claim 2, Computing the output power of the downlink shared control channel is calculated based on the indication value of the channel quality indicator reported in a certain period, and the calculated output power value in proportion to the TPC value reported by the terminal between the period. Transmitting power control method, characterized in that for changing. The method of claim 1, The downlink shared control channel is a transmission power control method, characterized in that the HS-SCCH of the HSDPA system. Calculating HS-SCCH output power of a specific slot every predetermined period using the CQI information of the previous subframe; After increasing the time slot, determining, according to the power increase / decrease command of the uplink transmission power control, the power of the next slot with the power increased or decreased by a gain corresponding to the power of the current slot. A transmission power control method of a link packet access system. The method of claim 6, HS-SCCH output power determination of the slot performs output power control using CQI in one or a plurality of subframes, and output power control using uplink transmission power control in a slot unit of one or a plurality of subframes. A transmission power control method of a high speed downlink packet access system, characterized in that. The method of claim 6, The output power control cycle of the HS-SCCH using the CQI is a cycle in which the CQI is reported, the transmission power control method of the high-speed downlink packet access system. The method of claim 6, The output power control cycle of the HS-SCCH using the CQI is a cycle in which several CQIs are reported. Performing power control of the HS-SCCH using uplink transmission power control; Detecting whether a specific mobile station is in soft handover, and then switching to power control of the HS-SCCH of the mobile station by using channel measurement information of a predetermined period reported by the mobile station when in a soft handover state; And a method of controlling power using a TPC in the case of non-soft handover. The method of claim 10, And a period in which a channel quality indicator is reported or a number of periods in which a channel quality indicator is reported. The method of claim 10, Power control of the HS-SCCH using the channel measurement information may include extracting an SIR value of a CPICH channel using channel measurement information reported by a mobile station; Calculating an HS-SCCH output power from the CPICH SIR value; And calculating a final HS-SCCH output power by adding a power margin to the calculated HS-SCCH output power. Performing HS-SCCH power control using uplink transmission power control; Receiving configuration information of radio link radio links set for the mobile station from the radio network controller, and then checking whether the mobile station has a soft handover state or whether a radio link has been added; Receiving a CQI reported for each subframe of a certain period when there is soft handover or addition of a radio link as a result of the checking; Extracting the CPICH SIR value measured by the mobile station from the reported CQI, and then calculating the HS-SCCH output power; And calculating a final HS-SCCH output power by adding a power margin to the calculated HS-SCCH output control. The method of claim 13, Performing a power control using an uplink TPC when the mobile station is not in the soft handover state or the number of the radio links is changed to 1 as a result of the confirmation of the soft handover state or the addition of the radio link. A transmission power control method of a high speed downlink packet access system. The method of claim 13, And a wireless network controller controls performance of power control using a TPC and power control using a CQI to a base station. Instructing, by the radio network controller, the base station to control the type of power control of the mobile station; And switching to a corresponding power control of the HS-SCCH according to a method corresponding to the power control type, and performing power control. The method of claim 16, The power control method of notifying the base station is classified into a power control method using an uplink TPC and a power control method using a CQI. Performing transmission power control of the HS-SCCH using the uplink TPC; Detecting the required power of the HS-SCCH of the corresponding mobile station by a required power value of the radio network controller or an internal measurement of the base station, and then switching to and performing power control using the CQI if the detected required power is greater than or equal to a threshold; And switching to and performing power control using a TPC when the detected HS-SCCH required power is less than or equal to a threshold.