KR20090011117A - Method for tracking block error rate in a base station of a mobile communication systme using high speed downlink packet access protocol - Google Patents

Abstract

A method for tracking a block error rate(BLER) in a base station of a mobile communication system using the high speed downlink packet access(HSDPA) method is provided to save the transmission power by increasing the BLER in case of a cell in which the number of data calls is small, and increase the QoS of transmission data by lowering the BLER in case of a hot spot. A window size is set up, and a target BLER is set up according to the transmission power(Pp) which a base station uses(S802). The transmission power(Pp) is measured, and then is compared with the maximum power(Pmax) which the base station can use for the transmission. If the transmission power(Pp) is bigger than 0.7Pmax, a target block error rate(tBLET) is set up as a value bigger that 10%. If the transmission power(Pp) is smaller than 0.3Pmax, the target block error rate is set up as a value(Tl) smaller than 10%. In case of being 0.3Pmax<=Pp<=0.7Pmax, the target block error rate is set up as 0.1 which is the same value as the standard of 3GPP TS25.214.

Description

A method for tracking block error rate in a base station of a mobile communication system using a high speed forward packet access method.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of tracking a block error rate (BLER) in a base station of a mobile communication system using a high speed downlink packet access (HSDPA), particularly in a cell having a small data call. The present invention relates to a method of dynamically operating a block error rate by reducing the BLER to save transmission power by increasing the power consumption, or in the case of a hot spot or a hot spot where the base station does not use much power, thereby improving the quality of service of the transmission data.

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. As a result, it is aimed at providing a more improved mobile communication service. For the standardization of UMTS, in December 1998, ETSI in Europe, ARIB / TmaxC in Japan, T1 in the US and TmaxA in Korea were referred to as the Third Generation Partnership Project (hereinafter referred to as "3GPP"). The detailed specification of UMTS is being prepared so far.

In 3GPP, UMTS standardization work is divided into 5 Technical Specification Groups (hereinafter referred to as "TSG") in order to develop UMTS quickly and efficiently. Doing. Each TSG is responsible for the development, approval, and management of standards within the relevant areas, among which the Radio Access Network ("RAN") group (TSG-RAN) uses WCDMA access technology in UMTS. We will develop a specification for UMTS wireless network (Universal Mobile Telecommunications Network Terrestrial Radio Access Network (hereinafter referred to as "UTRAN")).

The TSG-RAN Group is again made up of a Plenary Group and four Working Groups. Working Group 1: WG1 develops a specification for the physical layer (first layer), and Working Group 2: WG2 is the data link layer (second layer) and network layer ( 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 determines the performance of radio link performance. Related requirements and requirements for radio resource management are discussed.

1 is a diagram showing the structure of 3GPP UTRAN. As shown, UTRAN 110 is composed of one or more Radio Network Sub-systems (hereinafter referred to as "RNS") 120,130, each of the RNS (120,130) and one RNC (121,131) It consists of one or more base stations (Node Bs) 122, 123, 132, 133 managed by the RNCs 121, 131. The RNC (121, 131) is connected to the Mobile Switching Center (MSC) (141) for circuit switched communication with the GSM network, the SGSN (Serving GPRS Support Node) for packet switched communication with the GPRS (General PACKet Radio Service) network 142 is connected.

In addition, the base station (Node B) 122, 123, 132, 133 is managed by the RNC (121, 131) and receives information sent from the physical layer of the terminal 150 in the uplink, the access point of the UTRAN to the terminal in the downlink The data is transmitted to the terminal 150 as an access point. 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 responsible for 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 protocol structure of a radio access interface between a UE and a UTRAN based on the 3GPP radio access network standard. The radio access interface protocol of FIG. 2 consists of a physical layer (PHY), a data link layer, and a network layer vertically, and horizontally controls a control plane for transmitting control signals and a user for transmitting data information. It is divided into 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, such as network interface and call maintenance and management, is transmitted.

The protocol layers of FIG. 2 correspond to the lower three layers of the Open System Interface (OSI) reference model, which is well known in communication systems.

The first layer L1 performs a role of a physical layer (PHY) for the wireless interface, and a transport channel with the upper medium access control layer (hereinafter, referred to as MAC) layer. Are connected via Data transmitted to the physical layer through a transport channel is transmitted to a receiver by applying 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 a WCDMA network. The second layer (L2) includes a MAC layer, a Radio Link Control (RLC) layer, a Packet Data Convergence Protocol (PDCP) layer, and a broadcast / multiple. It is divided into a broadcast control (Broadcast / Multicast Control: "BMC") layer.

The MAC layer delivers 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 for transmitting control plane information, and a traffic channel is used for transmitting user plane information. 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 for the transmission by the segmentation and concatenation function of the RLC SDUs transmitted from the upper layer, and performs an automatic repeat request for retransmission of the lost RLC PDU during transmission. ARQ) function can be performed. It operates in three ways: transparent mode, unacknowledged mode, and acknowledgment mode, depending on how the RLC SDU is processed from the upper layer.In the RLC layer, the RLC SDU or RLC descended from the upper layer. There is an RLC buffer for storing PDUs.

The PDCP layer sits on top of the RLC layer, making it suitable for data transmitted over a network protocol such as IPv4 or IPv6 to be transmitted at 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 makes it possible to transmit a message transmitted from a Cell Broadcast Center (CBS) 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.

The PDCP layer and the BMC layer are connected to the SGSN because they use a packet-switched method, 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 layer connected to the upper layer. In the case of belonging to the control plane corresponds to the case of receiving data from the radio resource control (hereinafter referred to as "RRC") layer, otherwise it corresponds to the user plane. In general, the user service transmission service of the user data provided to the upper layer by the second layer (L2) in the user plane is defined as a radio bearer (Radio Bearer: RB), the upper layer by the second layer (L2) in the control plane The transmission service of the control information provided as 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. The entities of the RLC layer and PDCP layer can perform independent functions within 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 2Mbps in indoor and pico-cell environments and 384kbps in typical wireless environments. 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, HSDPA system is expected to support up to 8 ~ 10Mbps speed in downlink, and provide shorter latency and improved capacity. To provide increased transmission speed and capacity, the HSDPA system uses Link AdaPmaxation (hereinafter referred to as "LA"), Hybrid Automatic Repeat request (hereinafter referred to as "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 are introduced.

The link adaptation technique (LA) uses a modulation and coding scheme ("MCS") according to the state of the channel. If the channel state is good, the link adaptation technique (LA) has a high level such as 16QAM and 64QAM. If a modulation method is used and 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 combines the data used and retransmitted in conjunction with the physical layer with previously received data to ensure a higher decoding success rate. 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, it is possible to greatly increase the transmission efficiency of the packet.

The FCS method is similar to the existing 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 occurs a lot. 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. A representative example is the 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 the 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.

Unlike the existing WCDMA system R'99 / R'4, the HS-DSCH has a short transmission time interval (TmaxI) (3 slots, 2 ms), and various modulation codes for high data rates. Supports a set of modulation codes (MCS), and by selecting an MCS that is most suitable for a channel situation, an optimal throughput can be raised. To this end, a hybrid ARQ (HARQ) technique, which combines an automatic repeat request (ARQ) technique and a channel coding technique, is adopted to ensure reliable transmission.

Control information is required for HS-DSCH, and this information is transmitted through a shared control channel (HS-SCCH) introduced in the HSDPA standard. A physical channel corresponding to the transport channel HS-DSCH is described as follows.

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 codes having a Spreading Factor (SF) of 16. The HS-DSCH subframe consists of three slots. The HS-PDSCH channel carries QPSK or 16QAM 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 16QAM. 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, which is a downlink shared control channel (HS-SCCH) and uplink HS- which are introduced in the HSDPA standard. It is transmitted through the High Speed Dedicated Physical Control Channel (DPCCH). 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 HARQ-ACK and CQI information. The uplink DPCCH includes TPC, Pilot, TFCI, and FBI information as in the existing system.

Control information transmitted on the downlink shared control channel can be largely 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 HARQ and CQI (Channel Quality Indicator, Channel Quality Indicator).

The frame of the HS-DPCCH is divided into 5 subframes of 2ms in length, and one subframe consists of 3 slots. Ack / Nack information for HARQ 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 transmits the downlink HS- by the HARQ mechanism. Informs the Ack or Nack information about 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, it is possible to support several users at the same time, the control information for this (control information) uses a shared control channel (shared control channel) assigned to each user.

Power control of this common control channel is performed according to a TPC command transmitted 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.

When the UE receives the forward channel signal, the UE measures channel quality (CQ) for the received forward channel signal and reports the measured channel quality to the base station. Then, the base station receives the channel quality information from the UE and determines the MCS level of the High Speed Downlink Shared Channel (HS-DSCH) in which data is transmitted to the actual UE according to the channel quality. A transport format and resource related information (TFRI) is generated. For example, if the base station sees and receives the channel quality from the UE and the channel is in good condition, the modulation method may select a modulation method that increases the bit rate but decreases the bit error rate, such as quadrature amplitude modulation (QAM). On the contrary, when the channel condition is poor, a modulation method such as quadrature phase shift keying (QPSK) is selected.

Hereinafter, a method of generating a CQI by the UE according to the quality of a forward channel signal will be described.

First, the CQI is used by the base station to determine the MCS level of the HS-DSCH. The base station uses a high MCS level, i.e., a high transmission rate if the state of the forward channel is good, whereas the base station uses a high MCS level if the state of the forward channel is poor. This small, low MCS level is determined and the HS-DSCH is transmitted at the determined MCS level. Typically, channel quality is determined through measurements of the Carrier to Interference Ratio (C / I) of the Common Pilot Channel (CPICH) (hereinafter referred to as "CPICH"). You can decide. However, if the UE simply transmits only the channel state to the base station, diversity for the UE is not guaranteed. That is, even in the same channel state, if the performance of the UE is better, it may be able to support a higher level of MCS than the UE having a low performance. However, since the base station does not know the performance of the UE, the base station will determine the acceptable MCS level based on the UE having normal performance. Therefore, the UE preferably generates a CQI considering the UE's own performance.

In addition, as described above, the base station receives the CQI from the UE to determine the MCS level of the HS-DSCH, and if the base station unilaterally determines the MCS level for the HD-DSCH, it is impossible to consider the diversity of the UEs. In order to determine the MCS level in consideration of the diversity of UEs, UEs must inform UEs to consider their own performance. That is, the UE checks the current channel state by measuring C / I from the CPICH, and according to the checked channel state, the maximum acceptable transport format and resource combination (TFRC: Transport Format and Resource Combination (TFRC)) "TFRC" is determined as the CQI. The information included in the TFRC means a modulation scheme of a HS-DSCH channel, a transport block set (TBS) size, and the number of acceptable HS-DSCH channels. When the base station receives the TFRC considering the performance of the UE from the UE, it determines the TFRI to correspond to the received TFRC. TFRI means MCS level, HS-DSCH channelization code information, transmission format, etc. to be used in HS-DSCH. That is, the TFRC reports the maximum acceptable limit of the UE to the base station, and the base station determines the TFRI based on the capacity of the base station and the TFRC reported by the UE.

On the other hand, the standard of 3GPP TS25.214 specifies that the terminal generates a CQI considering 10% BLER and transmits it to the network. The CQI consists of 30 grades based on the Signal to Interference Ratio (SIR) and is defined by TS25.214. Accordingly, the network receiving the CQI from the terminal selectively schedules a TFRI (Transport Format & Radio Resource Indicator) according to the corresponding CQI and makes the BLER approximately 10%.

7 is a flowchart of a conventional BLER tracking method. First, when a window size is input (S702), a block error rate (BLER) is calculated by counting Ack / Nack sent from the UE for a transport block during the window size (S704). Next, the calculated block error rate is compared with 0.1 specified in TS25.214 (S708). If the BLER is less than 0.1, the power level is reduced or a larger sized transport block is selected (S710). If the BLER is equal to 0.1, it is maintained without changing power or TFRI (S712). If the BLER is greater than 0.1, the power level is increased or a smaller sized transport block is selected (S714). For example, if the window is 100, Ack or Nack is counted for 100 transport blocks scheduled in the network. At this time, if 98 Ack occurs, BLER is 2%, so lower the transmission power for the next data to be scheduled or set TFRI high so that more data can be sent and sent so that an error (that is, a Nack) occurs. do. Next, the flow returns to step S704 to check the number of Ack / Nack for the scheduling block.

However, such an operation saves transmission power by taking a large BLER in a cell with a small number of data calls, or lowers the BLER in an area or hot spot where the base station does not use much power, thereby improving the quality of service of the transmitted data. There is a problem that such dynamic operation is impossible.

Accordingly, the present invention saves transmission power by taking a large BLER in a base station of a mobile communication system using a high-speed forward packet access method, or in an area or hot spot where power consumption of the base station is not high. In this case, an object of the present invention is to provide a method for tracking a block error rate that enables dynamic operation such as lowering a BLER to improve a service quality of transmission data.

The present invention for achieving the above object is a method for tracking the block error rate in the base station of the mobile communication system using a high-speed forward packet access method, setting a target block error rate (BLock) according to the transmission power used by the base station Receiving the acknowledgment information of the mobile station for the predetermined number of transport blocks transmitted from the base station to the mobile station, calculating a block error rate for the corresponding channel, and transmitting a transmission parameter such that the calculated block error rate is equal to the target block error rate. It characterized in that it comprises a step of adjusting.

The present invention also provides a method for tracking a block error rate in a base station of a mobile communication system using a fast forward packet access method, the method comprising: setting a target block error rate (BLER) according to the number of calls serviced by the base station; Receiving the acknowledgment information of the mobile station for the predetermined number of transport blocks transmitted from the mobile station to calculate the block error rate for the corresponding channel, and adjusting the transmission parameter such that the calculated block error rate is equal to the target block error rate. It is another feature to include.

The present invention also provides a method for tracking a block error rate in a base station of a mobile communication system using a fast forward packet access method, the method comprising: setting a target block error rate (BLER) according to a type of service provided by the base station; Receiving the acknowledgment information of the mobile station for the predetermined number of transport blocks transmitted from the base station to calculate a block error rate for the corresponding channel, and adjusting the transmission parameter such that the calculated block error rate is equal to the target block error rate. It is another feature to include a.

According to the present invention, it is possible to dynamically operate the network by a very easy method of adjusting the target block error rate. In other words, a cell with few data calls sets the target block error rate a little higher and operates with a power margin, and sets a target block error rate a little lower for a cell using less base station power to increase the quality of service (QoS) for the data. In addition, according to the present invention the operator can operate the network in consideration of the performance deviation of the terminal.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

8 is a flowchart of a method for tracking a block error rate at a base station of a mobile communication system using a high speed forward packet access scheme according to the present invention.

First, the window size is set, and a target block error rate (BLER) is set according to the transmission power currently used by the base station (S802). A first embodiment of a method of setting a target block error rate is shown in FIG.

As shown, the base station measures the transmission power Pp currently used (S902) and compares it with the maximum power Pmax that the base station can use for transmission (S904). As a result of the comparison, if the transmission power Pp currently used by the base station is greater than 0.7Pmax, the target block error rate tBLET is set to a value Th greater than 10% (S906), and the transmission power currently used by the base station ( If Pp) is smaller than 0.3Pmax, the target block error rate tBLET is set to a value Tl smaller than 10% (S910). When 0.3Pmax≤Pp≤0.7Pmax, the target block error rate is set to the same value as that of the standard of 3GPP TS25.214 (that is, 0.1) (S908). Here, the values 0.3Pmax and 0.7Pmax, which are the setting criteria of the target block error rate, are just one example for explanation and may be variously changed according to a system.

Next, the mobile station receives acknowledgment information (i.e., Ack / Nack) for the transport block during the window size transmitted from the base station to the mobile station, and calculates a block error rate (cBLET) for the corresponding channel (S804). Next, the transmission parameter is adjusted so that the block error rate calculated in step S804 is equal to the target block error rate set in step S803 (S806).

If the transmission parameter to be adjusted is the magnitude of the transmission power, step S806 of adjusting the transmission parameter is shown in FIG. As shown, first, the block error rate cBLET calculated in step S804 is compared with the target block error rate tBLET set in step S802 (S1002). As a result of the comparison, when the calculated block error rate cBLET is smaller than the target block error rate tBLET, the size of the transmission power is reduced (S1004), and when the calculated block error rate cBLET is equal to the target block error rate tBLET, The magnitude of power is maintained (S1006), and if the calculated block error rate cBLET is greater than the target block error rate tBLET, the magnitude of the transmission power is increased (S1008).

If the adjusted transmission parameter is a Quality of Service (QoS) of transmission data, step S806 of adjusting the transmission parameter is shown in FIG. First, the block error rate cBLET calculated in step S804 is compared with the target block error rate tBLET set in step S802 (S1102). As a result of the comparison, the service quality is increased when the calculated block error rate cBLET is smaller than the target block error rate tBLET (S1104), and the service quality is maintained when the calculated block error rate cBLET is equal to the target block error rate tBLET. If the calculated block error rate cBLET is greater than the target block error rate tBLET, the service quality is lowered (S1108).

If the transmission parameter to be adjusted is the size of the transport block, step S806 of adjusting the transmission parameter is shown in FIG. As shown, first, the block error rate cBLET calculated in step S804 is compared with the target block error rate tBLET set in step S802 (S1202). As a result of the comparison, when the calculated block error rate cBLET is smaller than the target block error rate tBLET, the size of the transport block is increased (S1204), and when the calculated block error rate cBLET is equal to the target block error rate tBLET, The size is maintained (S1206), and if the calculated block error rate cBLET is larger than the target block error rate tBLET, the size of the transport block is reduced (S1208).

FIG. 13 is a flowchart for explaining a second embodiment of the target block error rate setting step S802 shown in FIG.

As shown, the base station measures the number Np of calls currently being served (S1302), and compares it with the lower limit Nl and the upper limit Nh (S1304). As a result of the comparison, if the number of calls Np currently being served by the base station is smaller than the lower limit Nl, the target block error rate tBLET is set to a value Th greater than 10% (S1306). If the number Np of calls currently being served by the base station is greater than the upper limit value Nh, the target block error rate tBLET is set to a value Tl smaller than 10% in consideration of the urban center area (S1310). When Nl≤Np≤Nh, the target block error rate is set to the same value as that of the standard of 3GPP TS25.214 (that is, 0.1) (S1308).

FIG. 14 is a flowchart for explaining a third embodiment of the target block error rate setting step S802 shown in FIG.

As shown, first, the type of service currently provided by the base station is determined (S1402). As a result of the determination, when the service provided by the base station is sensitive to delay such as a voice call and a video call, the target block error rate tBLET is set to a value Tl smaller than 10% (S1404 and S1406). If the service type is insensitive to delays such as wireless Internet, data provision, short message service (SMS) and multimedia message service (MMS), the target block error rate tBLET is set to a value Th greater than 10% (S1404). , S1408). Otherwise, the target block error rate is set to the same value as that of the standard of 3GPP TS25.214 (that is, 0.1) (S1404 and S1410).

According to the present invention, for example, in the case of a cell with a low data call such as a power area, the BLER is taken large to save transmission power, or in the case of a hot spot or a hot spot where the base station does not use much power, Dynamic operation such as lowering of service quality of transmission data is possible. In particular, regardless of the CQI level raised by the terminal or the level of the CQI due to the deviation of the terminal has the advantage of reducing the deviation of the terminal by adjusting the CQI to match the BLER in the network.

The foregoing embodiments are given as specific examples so that those skilled in the art (hereinafter, referred to as "ordinary skill") can easily understand and implement the present invention, and limit the scope of the present invention. I do not want to. Therefore, those skilled in the art should note that various modifications or changes can be made to these embodiments within the scope of the present invention. The scope of the invention is defined in principle by the claims that follow.

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

2 is a structural diagram of a radio access interface protocol of a 3GPP system;

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

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

5 is a diagram illustrating a frame structure of an uplink HS-DPCCH of an HSDPA system in a 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 conventional BLER tracking method.

8 is a flowchart illustrating a tracking method of the present invention.

9 is a flowchart for explaining a first embodiment of the target block error rate setting step S802 shown in FIG.

FIG. 10 is a flowchart for explaining the first embodiment of the transmission parameter adjusting step S806 in the embodiment shown in FIG.

FIG. 11 is a flowchart for explaining a second embodiment of the transmission parameter adjusting step S806 in the embodiment shown in FIG.

12 is a flowchart for explaining a third embodiment of the transmission parameter adjusting step S806 in the embodiment shown in FIG.

FIG. 13 is a flowchart for explaining a second embodiment of the target block error rate setting step S802 shown in FIG.

FIG. 14 is a flowchart for explaining a third embodiment of the target block error rate setting step S802 shown in FIG.

Claims (13)

A method for tracking a block error rate in a base station of a mobile communication system using a fast forward packet access method, Setting a target block error rate (BLER) according to a transmission power currently used by the base station; Receiving block acknowledgment information of the mobile station for a predetermined number of transport blocks transmitted from the base station to calculate a block error rate for the corresponding channel; Adjusting a transmission parameter such that the calculated block error rate is equal to the target block error rate. And a block error rate tracking method. The method of claim 1, The setting of the target block error rate If the transmission power used by the base station is greater than a predetermined value, the target block error rate is set to be greater than 10%. If the transmission power used by the base station is smaller than a predetermined value, the target block error rate is set to be less than 10%. A block error rate tracking method. The method of claim 1, And wherein the transmission parameter is a magnitude of a transmission power. The method of claim 3, wherein Adjusting the transmission parameter If the calculated block error rate is less than the target block error rate, the magnitude of the transmit power is reduced. If the calculated block error rate is equal to the target block error rate, the magnitude of the transmit power is maintained. If the block error rate is greater than the block error rate tracking method, characterized in that for increasing the size of the transmission power. The method of claim 1, The transmission parameter is A method of tracking a block error rate, characterized in that it is a quality of service (QoS) of transmission data. The method of claim 5, wherein Adjusting the transmission parameter If the calculated block error rate is less than the target block error rate, the service quality is increased, and if the calculated block error rate is equal to the target block error rate, service quality is maintained, and if the calculated block error rate is greater than the target block error rate, service is provided. A method for tracking a block error rate, characterized by lowering the quality. The method of claim 1, The transmission parameter is A method for tracking a block error rate, characterized in that the size of the transport block. The method of claim 7, wherein Adjusting the transmission parameter If the calculated block error rate is less than the target block error rate, the size of the transport block is increased. If the calculated block error rate is the same as the target block error rate, the size of the transport block is maintained, and the calculated block error rate is the target. If the block error rate is larger than the block error rate tracking method, characterized in that for reducing the size of the transport block. A method for tracking a block error rate in a base station of a mobile communication system using a fast forward packet access method, Setting a target block error rate (BLER) according to the number of calls currently served by the base station; Receiving block acknowledgment information of the mobile station for a predetermined number of transport blocks transmitted from the base station to calculate a block error rate for the corresponding channel; Adjusting a transmission parameter such that the calculated block error rate is equal to the target block error rate. And a block error rate tracking method. The method of claim 9, The setting of the target block error rate The target block error rate is set to be greater than 10% if the number of calls serviced by the base station is smaller than a predetermined value, and the target block error rate is set to be less than 10% if the number of calls serviced by the base station is greater than a predetermined value. How to track block error rate. A method for tracking a block error rate in a base station of a mobile communication system using a fast forward packet access method, Setting a target block error rate (BLER) according to a type of service currently provided by the base station; Receiving block acknowledgment information of the mobile station for a predetermined number of transport blocks transmitted from the base station to calculate a block error rate for the corresponding channel; Adjusting a transmission parameter such that the calculated block error rate is equal to the target block error rate. And a block error rate tracking method. The method of claim 11, The setting of the target block error rate And if the service provided by the base station is a call, setting the target block error rate to less than 10%. The method of claim 11, The setting of the target block error rate And if the service provided by the base station is wireless Internet, setting the target block error rate to be greater than 10%.

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