KR100844333B1 - Optimization method on criterion to identify a primary cell for the enhanced DSCH power control in 3GPP system - Google Patents

Abstract

The present invention is to optimize the criterion for the primary cell of the base station transmitting the DSCH for the advanced downlink shared channel power control of the asynchronous standard system of the third generation mobile communication standardization group.

According to an embodiment of the present invention, in determining a primary cell using only SSDT uplink signaling in power control of an advanced downlink shared channel, a first condition having a magnitude of a signal received from a mobile station or greater than a predetermined value and the base station itself Identify a second condition in which the cell identifier code of is equal to the primary cell identifier code transmitted from the mobile station, and a third condition in which in the uplink compression mode the puncturing occurs less than or equal to three divided by the length of the cell identifier; In the 3GPP system, the base station determines itself as a primary cell when all of the first to third conditions are satisfied.

Description

 Optimization method on criterion to identify a primary cell for the enhanced DSCH power control in 3GPP system}

1 is a structure of a 3GPP UTRAN.

2 is a protocol structure of a radio access interface.

3 is a diagram illustrating a configuration of a downlink shared channel (DSCH).

4 is a diagram illustrating a configuration of a dedicated channel (DCH).

5 is a flowchart for determining non-primary cells and primary cells in the uplink in conventional SSDT signaling.

6 is a flowchart illustrating a method of optimizing a criterion of primary cell in advanced DSCH power control according to an embodiment of the present invention.

7 is a flowchart of a signaling procedure for DSCH TFCI power control for the present invention.

The present invention transmits a DSCH for power control of an advanced downlink shared channel (E-DSCH) of an asynchronous IMT-2000 standard (UMTS) system of a third generation mobile communication standardization group (3GPP). The present invention relates to a method for optimizing primary cell criterion for advanced downlink shared channel power control in a mobile communication system to optimize the primary cell's primary cell criterion.

UMTS (Universal Mobile Terrestrial System) is a third generation mobile communication system that evolved from the Global System for Mobile Communications (GSM) system, the European second generation mobile communication standard.The GSM Core Network and Wideband Code Division Multiple Access (WCDMA) It aims to provide better mobile communication service based on access technology.

Here, the first generation mobile communication refers to the analog method, the second generation mobile communication means the evolution to the digital method, and the third generation method is commonly called IMT-2000, which means a breakthrough in communication capability.

And in December 1998, for the international standardization work of UMTS, national or national standards-setting bodies such as ETSI in Europe, ARIB / TTC in Japan, T1 in the US and TTA in Korea were established by The Third Generation Partnership Project (hereinafter abbreviated as 3GPP) is formed, and through this 3GPP, the detailed specification of UMTS, the European IMT-2000 system, is defined.

In 3GPP, UMTS standardization work is referred to as 5 Technical Specification Groups (hereinafter referred to as TSG) in consideration of independence of network components and their operation for rapid and efficient technology development of UMTS. Divided into proceeds. 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) is a WCDMA access technology (asynchronous) in UMTS. Develop specifications for the functions, requirements, and interfaces of the UMTS Terrestrial Radio Access Network (hereinafter referred to as UTRAN), a new radio access network to support CDMA).

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 (Node Bs) 122, 123, 132, 133 managed by the RNCs 121, 131. The RNC 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 mobile station 150 in the uplink, and transmits data to the mobile station 150 in the downlink It is responsible for the access point of the UTRAN to the mobile station transmitting to the mobile station. 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. The place that manages dedicated radio resources assigned to each mobile station is called a serving RNC (SRNC). The control RNC and the responsible RNC may be the same, but when the mobile station 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.

Figure 2 shows the structure of the interface protocol of the 3GPP radio access network standard for the mobile station and the network to wirelessly connect over the air.

Referring to FIG. 2, the radio access interface protocol consists of a physical layer (PHY), a data link layer, and a network layer horizontally, and a control plane and data for vertically transmitting control signals. It is divided into a user plane for transmitting information. Here, the user plane is an area in which traffic information of the user is transmitted, such as voice or IP packet transmission, and the control plane is an area in which control information is transmitted, such as interface or network maintenance and management of a network.

The protocol layers of FIG. 2 are based on the lower three layers of the seven-layer Open System Interface (OSI) reference model, which are well known in a communication system. The first layer (L1), the second layer (L2), It may be divided into a third layer (L3).

The first layer L1 serves as a physical layer (PHY) for the air interface, and a transport channel with a medium access control layer (hereinafter referred to as MAC) layer on the upper layer. It is connected through the channels and transmits the data delivered to the physical layer through the transport channel to the receiver using various coding and modulation methods suitable for the wireless environment.

The transport channel existing between the physical layer (PHY) and the MAC layer is a dedicated transport channel and a common transport depending on whether the mobile station is exclusively available or shared by multiple mobile stations. It is divided into channels (Common Transport Channel).

The second layer L2 serves as a data link layer, and allows various mobile stations 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.

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 for transmitting control plane information and a traffic channel is used for transmitting user plane information.

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 the lost RLC PDU 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 to a mobile station. In general, BMC transmits data through an RLC layer operating in an unresponsive mode.

For reference, since the PDCP layer and the BMC layer transmit only user data, they are located only in the user plane. 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, 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 mobile station 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 radio carrier setup (RB setup) refers to a process of defining characteristics of a protocol layer and a channel necessary for providing 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.

On the other hand, there is only one dedicated transport channel (DCH), but the common transport channel (Common Transport Channel) is divided into several types, of which the channel for transmitting unpredictable data There is a downlink shared channel (hereinafter referred to as DSCH).

FIG. 3 is a diagram illustrating a configuration of a downlink shared channel (DSCH). The downlink shared channel (DSCH) includes a 10 ms radio frame, which can be shared and used by different users in each frame. . This may be possible by several users being assigned one node per frame from a channelization code for the downlink shared channel (DSCH).

On the other hand, although the downlink shared channel (DSCH) is shared by multiple users, a code with a constant data rate at a particular moment can be used by only one user. Therefore, the downlink shared channel DSCH occupied by a specific mobile station MS is controlled by the mobile station occupying the channel.

Multiple users can be shared by multiple users by assigning one node per frame in the root channelization code for the DSCH. That is, the DSCH is a code multiplexing and time multiplexing channel shared by multiple users. Therefore, power control is performed by a user who occupies a DSCH occupied by a specific mobile station (MS).

Here, in W-CDMA, users are identified by a root channelization code. For example, when spreading factor (SF) = 4/8/15/32/64, each channelization code is 4/8/16/32/64. exist. The channelization code of the high spreading element is made from the channelization code of the low spreading element, wherein the channelization code of the low spreading element is called mother code and the root channelization code of the smallest spreading element among the mother codes It is called. That is, setting a root channelization code for the DSCH can allocate a channelization code having a high spreading factor therefrom.

In general, the downlink shared channel (DSCH) may operate in association with a dedicated channel (DCH). That is, the mobile station occupying the downlink shared channel (DSCH) necessarily has a dedicated channel (DCH). Referring to general power control, the mobile station (MS) measures the power of the dedicated channel (DCH) transmitted from the base station, and generates a transmit power control (TPC) command therefrom and transmits it to the base station. Then, the base station updates the power of the dedicated channel (DCH) based on the transmission power control command. In addition, the base station may update the power of the downlink shared channel (DSCH) by using the updated dedicated channel (DCH) power.

As such, the power of the dedicated channel (DCH) and the power of the downlink shared channel (DSCH) operate in conjunction. That is, as described above, the downlink shared channel (DSCH), which is a 3GPP downlink channel, is a joint channel used by several users by dividing time and codes. The downlink shared channel (DSCH) may or may not exist in time for one user. On the other hand, per user using the downlink shared channel (DSCH) in order to periodically transmit the pilot field (Filot Field) required for fast power control and to send control information of the downlink shared channel (DSCH) One dedicated channel (DCH) is used in combination, which is referred to as an associated dedicated channel (DCH). Accordingly, the downlink shared channel (DSCH) can communicate with each user in association with the associated dedicated channel allocated to each user.

4 is a diagram illustrating a configuration of a dedicated channel (DCH). Referring to FIG. 4, the dedicated channel DCH includes a radio frame having a frame period T _f of 10 ms, and includes 15 slots Slot # 0 to Slot # 14 for each radio frame. Here, one slot length (T _slot) is 2560 chips. In addition, the Dedicated Channel (DCH) is alternately interposed between a Dedicated Physical Data CHannel (DPDCH) and a Dedicated Physical Control CHannel (DPCCH). The dedicated channel DCH may carry N _data1 bits of data Data1 on the first physical data channel in order from the left, and TPC (N _TPC bits) and TFCI (N _TFCI bits) on the first physical control channel. . In addition, the next physical data channel may carry N _data2 bits of data Data2, and the second physical control channel may carry N _pilot bits of pilot signals. Here, the TFCI field contains information on a channel currently being transmitted. For example, the TFCI field may transmit information on the amount of data transmitted in the current radio frame, a coding method, and the like.

The dedicated channel (DCH) performs soft handover, while the DSCH channel does not perform soft handover. Thus, when the DCH is in soft handover state and the DSCH is transmitted from only one base station, different power control is required. That is, the TPC is generated by summing the powers from the various base stations, but since the DSCH channel is transmitted from one base station, power control of the DSCH cannot be accurately performed through the power control by the TPC. For this reason, another power control method should be applied to the DSCH channel.

When data of a user is simultaneously transmitted to one user through a dedicated channel (DCH) and a downlink shared channel (DSCH), the information on the dedicated channel (DCH) and the downlink shared channel ( DSCH) information should be transmitted at the same time. To this end, the TFCI field divides the bits included in the TFCI field transmitted per slot into two, one half may be used for a dedicated channel (DCH) and the other half for a downlink shared channel (DSCH).

Two methods may exist as a method for transmitting information about a dedicated channel (DCH) and a downlink shared channel (DSCH). That is, in the first method, TFCI information (TFCI1) for the dedicated channel (DCH) and TFCI information (TFCI2) for the downlink shared channel (DSCH) are one codeword based on one order (second order reed muller coding). (code word) is formed and transmitted. This is called Logical Split Mode. In the second method, TFCI information (TFCI1) for the dedicated channel (DCH) and TFCI information (TFCI2) for the downlink shared channel (DSCH) are different from each other through the first order reed muller coding. In this case, the bits of two codewords thus formed are mixed and transmitted. This is called Hard Split Mode. Here, the second method may transmit the TFCI field even when a dedicated channel (DCH) is transmitted by a different radio network controller (RNC). That is, TFCI information (TFCI2) for the downlink shared channel (DSCH) is transmitted only in a part of base stations in the entire radio link.

The transmit power control (TPC) command is a command for power control of an uplink channel, which can be used to change the power of the uplink (or reverse). The power of the channel may be measured using a pilot.

On the other hand, the scheme currently employed in the 3GPP system operates the SSDT signaling only on the uplink, and the mobile station determines the primary cell and transmits a corresponding cell ID code. The base station transmitting the DSCH then decodes the cell identifier code to determine whether it is a primary cell or a non-primary cell. In this case, the non-primary cell is determined as shown in FIG. 5.

1) The magnitude of the signal received by the base station from the mobile station must be greater than or equal to a certain value Qth. 2) Its cell identifier code must be different from the primary cell code sent from the mobile station. 3) In the case of uplink compressed mode, an appropriate level of puncturing should occur. The appropriate puncturing level should be below (int) Nid / 3. Nid is the length of the cell indicator code. Int is an integer.

Only when all three conditions are satisfied, the base station determines the non-primary cell and the rest is determined to be the primary cell. This is due to the technical characteristics of SSDT. That is, in SSDT, a dedicated physical channel (DPDCH) is transmitted only to a base station determined as a primary cell. When the base station to be determined as a primary cell occurs due to a poor channel condition, an active set (active set) is transmitted. In this case, all the base stations within the packet are determined to be non-primary cells, and thus, data transmission may not occur. In order to avoid this situation, if the above three conditions are satisfied, the non-primary cell is judged as a non-primary cell, and the data is not transmitted.

In the case of advanced downlink shared channel (E-DSCH) power control, only SSDT uplink signaling is used. Only the base station transmitting the DSCH in the active set decodes the SSDT identifier code so that the primary / non The primary will be determined. At this time, the other base station in the active set does not activate the SSDT. The base station determined as primary using only SSDT uplink signaling transmits the transmit power by subtracting the transmit power of the DSCH by the power offset corresponding to the primary cell. This is the power control obtained as a result of identifying the goodness of the channel state with that determined by the primary cell.

However, in the case of the high DSCH power control in the related art, only the SSDT uplink signaling is used to determine whether the primary / non-primary cell is used. However, since the criteria for determining the primary cell of the SSDT are used as it is, the DSCH performance may be degraded. .

That is, as mentioned above, there are two main cases in which the base station determines itself as the primary cell. The first is a case where the primary channel is judged to be a primary cell because the actual channel condition is good, and the second is a case where the primary channel is determined to eliminate the SSDT itself problem due to the poor reliability of the SSDT identifier code decoding due to the poor real channel situation. In the first case, the power can be efficiently used while guaranteeing the performance of the DSCH. In the second case, there is a problem in that the performance of the DSCH may be degraded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and prevents the case where the base station is inferior in the condition that the base station judges itself as the primary cell in the advanced downlink unique channel power control, and thus determines the primary cell as the primary cell. A method for optimizing primary cell decision criteria for advanced downlink control channel power control in a 3GPP system is proposed to provide a primary cell decision criterion so that the power can be efficiently used while guaranteeing the performance of the downlink shared channel. The purpose is to provide.

In order to achieve the above object, in the 3GPP system according to the present invention, the method of optimizing the criterion of the primary cell for the advanced downlink control channel power control,

In determining a primary cell using only SSDT uplink signaling in power control of an advanced downlink shared channel, the first condition that a signal received from the mobile station has a predetermined value or more, and the cell identifier code of the base station itself are determined by the mobile station. In the uplink compression mode, a second condition equal to the primary cell identifier code transmitted in the second embodiment and a third condition in which puncturing occurs below a value of dividing the length of the cell identifier by three are identified. When all are satisfied, the base station determines itself as the primary cell.

Preferably, when determining the primary cell, if the base station does not satisfy at least one of the first to third conditions, the base station determines that it is a non-primary cell.

Preferably, the criterion for determining the primary cell may be applied to the TFCI power control in the DSCH hard split mode.

Preferably, when it is determined as the primary cell, a power offset value corresponding thereto is signaled from the radio network controller to the base station.

Referring to the accompanying drawings, a method for optimizing the determination criterion of the primary cell in the advanced downlink shared channel power control in the 3GPP system according to the embodiment of the present invention is as follows.

Referring to FIG. 6, in power control of an advanced downlink shared channel, a primary cell is determined using only SSDT uplink signaling.                     

The first condition for determining the primary cell is that the magnitude of the received signal received from the mobile station is greater than or equal to a certain value Qth. In case of SSDT, if the received signal size of mobile station is not more than appropriate level, an error occurs during decoding of SSDT identifier. In this case, since all base stations in the active set may be declared as non-primary, the received signal is in proper procedure. If not abnormal, it is always considered primary.

And, the second condition is that its cell identifier code must be the same as the primary cell identifier code transmitted from the mobile station.

The third condition is that in the case of uplink compressed mode, an appropriate level of puncturing should occur and for this purpose, the appropriate puncturing level should be an integer value of less than or equal to Nid / 3. Where Nid is the cell identifier code length. In the case of uplink compressed mode, puncturing occurs in dpch and puncturing occurs in SSDT identifier code. If the puncturing is not less than or equal to Nid / 3, the identifier code decoding becomes very poor and should be less than or equal to that. In the uplink compression mode, puncturing occurs in the DPCH, and then puncturing occurs in the SSDT identifier code, and if the puncturing is not less than Nid / 3, the id code decoding becomes very poor. It must have a value.

Only when all three conditions are satisfied, the base station determines itself as a primary cell, and if the rest, that is, even one condition is not satisfied, it is determined as a non-primary cell.

Therefore, if only the base station transmitting the DSCH in the active set decodes the SSDT identifier code to determine the primary cell, the other base station in the active set does not activate the SSDT. Therefore, the base station determined as the primary cell using only SSDT uplink signaling subtracts the transmit power of the DSCH by a power offset corresponding to the primary cell. This is the result of identifying the primary cell and the goodness of the channel state.

The TFCI information (TFCI1) for the dedicated channel (DCH) and the TFCI information (TFCI2) for the downlink shared channel (DSCH) are formed through different codings, respectively. This is the case where bits of two codewords are mixed. This is called Hard Split Mode. Here, the second method may transmit the TFCI field even when a dedicated channel (DCH) is transmitted by a different radio network controller (RNC). That is, TFCI information (TFCI2) for the downlink shared channel (DSCH) is transmitted only in a part of base stations in the entire radio link.

Here, as a method for transmitting information about a dedicated channel (DCH) and a downlink shared channel (DSCH), the hard split mode may include TFCI information (TFCI1) and downlink shared channel (DSCH) for the dedicated channel (DCH). TFCI information (TFCI2) for is a case where different codewords are formed through respective codings (first order Reed Muller coding), and bits of the two codewords thus formed are mixed and transmitted. The power control of the DSCH hard split mode may be applied as a criterion for determining by using the above first to third conditions for the primary cell.                     

The transmit power control (TPC) command is a command for power control of an uplink channel, which can be used to change the power of the uplink (or reverse). The power of the channel may be measured using a pilot.

In addition, when it is determined as the primary cell, a corresponding power offset value is signaled from the radio network controller to the base station.

That is, when it is determined as a primary cell, the power offset value corresponding thereto is included in a control frame including an update message of radio link parameters during radio setup between the control station and the base station Node B as shown in FIG. 7. Signaled. It is always intended to use the TFCI power offset (PO) indicated in the NBAP and RNSAP messages of the control plane when initially setting up the radio link, regardless of the movement of the mobile station or the variation of the number of radio links transmitting TFCI2. If it is determined as a primary cell, the corresponding TFCI Power Offset value is transmitted using a Node B Application Part (NBAP) and a Radio Network Subsystem Application Part (RNSAP) signaling message in the control plane to transfer the corresponding TFCI Power Offset value between the control station and the base station or between the control stations. Sent during radio link setup.

As described above, in the 3GPP system according to the present invention, according to the primary cell determination criterion optimization method in the high-level downlink shared channel power control, the criterion for determining the primary cell is a criterion of receiving signal having a predetermined value or more and a cell identifier. When the primary cell identifier and the primary cell identifier are the same and puncturing that the length of the cell identifier code divided by 3 is satisfied, the primary cell is judged to be the primary cell, thereby enabling efficient power usage while maintaining the performance of the downlink shared channel. It's effective.

Claims (4)

In determining a primary cell using only SSDT uplink signaling in controlling power of an advanced downlink shared channel (E-DSCH), A first condition in which the magnitude of the signal received from the mobile station is equal to or greater than a certain value, a second condition in which the base station's own cell identifier code is the same as the primary cell identifier code transmitted from the mobile station, and puncturing in the uplink compression mode High level downlink control channel in 3GPP system, characterized in that the base station determines itself as the primary cell when all the first to third conditions are satisfied by checking the third condition occurring below the value of the cell identifier divided by three. A method of optimizing the criterion of the primary cell for power control. The 3GPP system of claim 1, wherein the base station determines itself as a non-primary cell when at least one of the first to third conditions is not satisfied when determining the primary cell. A method of optimizing judgment criteria of primary cells for link control channel power control. The method of claim 1, And a criterion for determining the primary cell may be applied to TFCI power control in a DSCH hard split mode. 3. The method of claim 1, And a power offset value corresponding to the determination of the primary cell is signaled from the radio network controller to the base station. 3.

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