Patent Publication Number: US-7907570-B2

Title: HSDPA CQI, ACK, NACK power offset known in node B in SRNC

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 10/434,413 filed May 8, 2003 now U.S. Pat. No. 7,343,172, from which priority is claimed under 35 USC § 119 to U.S. Provisional Application Ser. No. 60/379,917 filed May 9, 2002 
    
    
     BACKGROUND OF THE INVENTION 
     As an enhancement to the release99/release4 (rel99/rel4) downlink shared channel (DSCH) concept in the third generation partnership project (3GPP) shown in  FIG. 1(   a ) it has been agreed to add a so-called High Speed Downlink Packet Access (HSDPA) concept as a part of the 3GPP rel5 universal terrestrial radio access network (UTRAN) architecture as shown in  FIG. 1(   b ). In  FIG. 1(   a ) the DSCH is transmitted on a downlink Physical Downlink Shared CHannel (PDSCH)  10 . In principle, the new HSDPA concept of  FIG. 1(   b ) is an enhancement, because the leading idea in 3GPP has been to make HSDPA as an evolution from the shared channel concept not as a revolution. Therefore the defined solutions should resemble as much as possible the solutions which have already been defined for the shared channels. The basic idea behind the HSDPA is to offer a shared high speed channel with a higher data rate and a quick retransmission mechanism (i.e. with HARQ (=Hybrid Automatic Repeat Request)) from Node B. As can be seen by comparing  FIG. 1(   b ) to  FIG. 1(   a ), the Node B is given more intelligence for the purpose of handling retransmissions and scheduling functions, thus reducing the round trip delay between the mobile device and the RNC formerly handling retransmissions in  FIG. 1(   a ). This makes retransmission combining feasible in the mobile device. In place of the variable spreading factor and fast power control used for the DSCH of  FIG. 1(   a ), the HS-DSCH of  FIG. 1(   b ) uses adaptive modulation and coding (AMC) in addition to the HARQ. A much smaller transmission time interval (TTI) of two milliseconds is also used instead of the 10 or 20 milliseconds of the DSCH. Also, the media access control (MAC) is located in the node B instead of the RNC. The AMC part of HSDPA utilizes adaptation of code rate, the modulation scheme, the number of multi-codes employed, as well as the transmit power per code. Even though many parameters are defined in the Radio Network Subsystem Application Part (RNSAP; see 3GPP TS25.423 v5.0.0) and Node B Application Part (NBAP; see 3GPP TS25.433 v5.0.0) to support HSDPA, the HSDPA discussion is on-going in 3GPP and many useful parameters are being added. 
     The user equipment is able to send a channel quality indicator (CQI) on the uplink HS-DPCCH (high speed dedicated physical control channel). It indicates the selected transport format resource combination (TFRC) and multi-code number currently supported by the UE. 
       FIG. 2  shows a radio protocol architecture for HSDPA taken from FIG. 5.1-1 of 3GPP TS 25.308 v5.2.0 (March 2002). According to that specification, the new functionalities of hybrid ARQ and HSDPA scheduling are included in the MAC layer. In the UTRAN these functions are included in a new entity called MAC-hs located as shown in the Node B in  FIG. 2 . The transport channel that the HSDPA functionality will use is called HS-DSCH (High Speed Downlink Shared Channel) and is controlled by the MAC-hs. The MAC protocol configuration shown is one of two possible configurations on the UTRAN side presented in the aforementioned specification. The illustrated configuration is provided with MAC-c/sh. In this case, the MAC-hs in Node B is located below MAC-c/sh in the RNC. MAC-c/sh provides functions to HSDPA already included for DSCH in the Release &#39;99. The HS-DSCH FP (frame protocol) will handle the data transport from SRNC to CRNC (if the lur interface is involved) and between CRNC and the Node B. Another configuration without MAC-c/sh is possible. In that case (see FIG. 5.1-2 of the aforementioned specification, the CRNC does not have any user plane function for the HS-DSCH. MAC-d in SRNC is located directly above MAC-hs in Node B, i.e. in the HS-DSCH user plane the SRNC is directly connected to the Node B, thus bypassing the CRNC. Both configurations are transparent to both the UE and Node B.  FIG. 2  hereof shows the respective radio interface protocol architecture with termination points. The same architecture supports both FDD and TDD modes of operation, though some details of the associated signaling for HS-DSCH are different. 
       FIG. 3  (see FIG. 6.2.2-1 of 3GPP TS 25.308 v5.2.0) shows UTRAN side MAC architecture/MAC-c/sh details. The data for the HS-DSCH is subject to flow control between the serving and the drift RNC. A new flow control function is included to support the data transfer between MAC-d and MAC-hs. 
       FIG. 4  shows UTRAN side MAC architecture/MAC-hs details (see FIG. 6.2.3-1 of 3GPP TS 25.308 v5.2.0). According to section 6.2.3 of the aforementioned specification, the MAC-hs is responsible for handling the data transmitted on the HS-DSCH. Furthermore it is its responsibility to manage the physical resources allocated to HSDPA. MAC-hs receives configuration parameters from the RRC layer via the MAC-Control SAP. There shall be priority handling per MAC-d PDU in the MAC-hs. The MAC-hs is comprised of four different functional entities: 
     Flow Control: 
     This is the companion flow control function to the flow control function in the MAC-c/sh in case of Configuration with MAC-c/sh and MAC-d in case of Configuration without MAC-c/sh. Both entities together provide a controlled data flow between the MAC-c/sh and the MAC-hs (Configuration with MAC-c/sh) or the MAC-d and MAC-hs (Configuration without MAC-c/sh) taking the transmission capabilities of the air interface into account in a dynamic manner. This function is intended to limit layer  2  signaling latency and reduce discarded and retransmitted data as a result of HS-DSCH congestion. Flow control is provided independently by priority class for each MAC-d flow. 
     Scheduling/Priority Handling: 
     This function manages HS-DSCH resources between HARQ entities and data flows according to their priority class. Based on status reports from associated uplink signaling either new transmission or retransmission is determined. Further it sets the priority class identifier and TSN for each new data block being serviced. To maintain proper transmission priority a new transmission can be initiated on a HARQ process at any time. The TSN is unique to each priority class within a HS-DSCH, and is incremented for each new data block. It is not permitted to schedule new transmissions, including retransmissions originating in the RLC layer, within the same TTI, along with retransmissions originating from the HARQ layer. 
     HARQ: 
     One HARQ entity handles the hybrid ARQ functionality for one user. One HARQ entity is capable of supporting multiple instances (HARQ process) of stop and wait HARQ protocols. There shall be one HARQ process per TTI. 
     TFC Selection: 
     Selection of an appropriate transport format and resource combination for the data to be transmitted on HS-DSCH. 
       FIG. 1(   c ) shows further details of the proposed UTRAN side overall MAC architecture including the new MAC-hs. MAC-hs provides the essential functionalities to support HSDPA. MAC-hs has the scheduling function as well as HARQ. 
     Currently in 3GPP, the SRNC is supposed to send the CQI Power Offset, ACK Power Offset and NACK Power Offset to the UE via RRC layer messages. The Power Offsets will be defined as relative to the DPCCH pilot bit. Then the UE will use these Power Offsets as follows: 
     When an uplink HS-DPCCH is active, the relative power offset Δ HS-DPCCH  between the DPCCH and the HS-DPCCH for each HS-DPCCH slot shall be set as follows: 
     For HS-DPCCH Slots Carrying HARQ Acknowledgement: 
     
         
         Δ HS-DPCCH =Δ ACK  if the corresponding HARQ Acknowledgement is equal to 1 
         Δ HS-DPCCH =Δ NACK  if the corresponding HARQ Acknowledgement is equal to 0
 
For HS-DPCCH Slots Carrying CQI:
 
         Δ HS-DPCCH =Δ CQI  
 
The values for Δ ACK , Δ NACK  and Δ CQI  are set by higher layers (RRC message). The quantization of the power offset can be found in 3GPP TS 25.213 at Table 1A for instance.
 
       
    
     DISCLOSURE OF INVENTION 
     But in the current 3GPP specification, there is no means to deliver these Power Offsets to Node B. Referring to  FIGS. 1(   c ) and  FIG. 2 , the prior art Node B of  FIG. 1(   a ) did not have the MAC-hs or complementary HS-DSCH FP layers. If Node B were to know the CQI Power offset, which is an object of the present invention, the Node B receiver could utilize this value for scaling the CQI signal. Scaling the CQI signal is related to the signal level setting, and is used typically in a digital base band implementation, to avoid overflow (i.e. signaling saturation) or underflow (i.e. quantization noise). In ASIC and DSP SW implementations, word length constraints are applied and signals must be scaled accordingly to match with the processing word lengths. If the power offsets for multiple signals are not known by the Node B, as is the case now, signal levels would have to be detected or alternatively in a worst case the Node B receiver would have to be made available for a possible maximum range of each signal. Especially in this case, both fading on the radio path and adaptation POs extend the required range. Signaling to Node B removes the later proportion for the required range. Therefore, if Node B knows the CQI Power Offset then it simplifies receiver implementation (i.e. when measuring DPCCH power level, CQI power level can be calculated and Node B can adjust gains in the different parts of receiver in a simple manner). 
     If Node B knows the ACK Power Offset and the NACK Power Offset, Node B can utilize these values to detect the ACK/NACK signal. For the ACK and NACK detection, the Node B receiver must also detect the 3 rd  state, DTX (no signal). This requires setting signal detection thresholds. This detection will be more accurate when it is set based on signaled POs than when it is set based on measured offsets. 
     Since ACK/NACK is a level based detection, if Node B already knows the POs of ACK/NACK, it can detect the signal easily. 
     If Node B knows the CQI Power Offset it can calculate the CQI power with DPCCH power, Node B doesn&#39;t need to measure the offset individually. It can make Node B receiver implementation easier. 
     If Power Offsets are not given by signaling, Node B is required to measure these Power Offsets individually. This is similar with beta parameters, which are given for DPCCH and for DPDCH, to indicate power offset between those two dedicated physical channels. Of course, in these schemes, the Node B receiver must still detect the DPCCH level, which is the reference for all the Power Offsets, but it doesn&#39;t need to detect other signal levels (CQI&#39;s, ACKs &amp; NACKs) individually for all multiple signals and this reduces Node B work significantly. 
     Furthermore it is anticipated that giving Power Offsets to the Node B will make the standard further future-proof when supporting some interference cancelling methods. 
     Currently, no description can be found from 3GPP specifications or technical reports about this problem and how to solve it. Therefore, there is no prior art recognition of the problem and consequently no solution either. Without knowing the CQI Power Offset, ACK Power Offset and NACK Power Offset, the Node B receiver has to search the signal for whole possible ranges. 
     This invention introduces CQI Power Offset, ACK Power Offset and NACK Power Offset on RNSAP and NBAP signaling or HS-DSCH FP. 
     Since the object is for both the UE and Node B to know the same values, there are two possibilities during the RL setup phase:
     (1) SRNC decides the Power Offsets and includes them in the RL SETUP REQUEST message. SRNC also sends the same information to the UE with a proper RRC message.   (2) Node B decides the Power Offsets and includes them in the RL SETUP RESPONSE message. And the SRNC sends the same Power Offsets to the UE with the proper RRC message.
 
And, there are 3 possibilities to change the POs.
   1) SRNC decides to change the Power Offsets and include them in the RL RECONFIGURATION PREPARE message. SRNC also sends the same information to UE with proper RRC message.   2) SRNC decides to change the Power Offsets and include them in the RADIO INTERFACE PARAMETER UPDATE control frame (It should be noted that the name of the control frame can be different than that). SRNC also sends the same information to UE with proper RRC message.   3) Node B decides to change the Power Offsets. In this case there is no existing mechanism for Node B to initiate changing the Power Offsets during the connection and there may be a need to define a new procedure. Alternatively, it could be done in such a way that the SRNC initiates Power Offsets change procedure (e.g. SHO case) by sending an RL RECONFIGURATION PREPARE message with HO indication. Then Node B decides new Power Offsets and sends them back in an RL RECONFIGURATION READY message. SRNC also sends the same information to UE with proper RRC message. The RL RECONFIGURATION PREPARE and RL RECONFIGURATION message formats already exist and can be adapted to the purposes of the invention.   

     Once Node B has the CQI Power Offset, ACK Power Offset and NACK Power Offset, it will apply CQI Power Offset for CQI slot scaling and ACK Power Offset and NACK Power Offset for ACK and NACK slot detection. 
     These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 : UTRAN side overall MAC architecture showing the defined HSDPA network architecture in 3GPP. The figure shows a new MAC-hs entity, which is connected, to the MAC-c/sh through lub-interface. The used transport channel under MAC-hs are HS-DSCH, which corresponds in rel99 shared channel concept DSCH transport channel. 
         FIG. 2 : Radio Interface Protocol Architecture of HSDPA. The defined protocol stack defines the HS-DSCH FP protocol to provide the HSDPA FP data frames through lub-interface. 
         FIG. 3 : UTRAN side MAC architecture/MAC-c/sh details. 
         FIG. 4 : UTRAN side MAC architecture/MAC-hs details. 
         FIG. 5 : In case SRNC sets CQI PO, ACK PO and NACK PO—RL Setup Phase. 
         FIG. 6 : In case Node B sets CQI PO, ACK PO and NACK PO—RL Setup Phase. 
         FIG. 7   a:  In case SRNC decides to change the values of CQI PO, ACK PO and NACK PO—Using Control Plane protocol. 
         FIG. 7   b:  In case SRNC decides to change the values of CQI PO, ACK PO and NACK PO—Using User Plane protocol. 
         FIG. 8 : In case SRNC decides to change the values of CQI PO, ACK PO and NACK PO—Using User Plane protocol—Frame structure. 
         FIG. 9 : In case Node B sets CQI PO, ACK PO and NACK PO—RL Setup Phase. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Abbreviations 
     
         
         CRNC Control RNC (network element) 
         DPCCH Dedicated Physical Control Channel 
         DPCH Dedicated Physical Channel 
         DPDCH Dedicated Physical Data Channel 
         DSCH Downlink Shared Channel (transport channel) 
         FDD Frequency Division Duplex (operation mode) 
         FP Frame Protocol 
         HARQ Hybrid Automatic Repeat Request (function) 
         HO Hand Over 
         HS-DSCH High Speed-Dedicated Shared Channel (transport channel) 
         HS-PDSCH Physical Downlink Shared Channel 
         HS-SCCH Shared Control Channel for HS-DSCH 
         HS-SICH Shared Info Channel for HS-DSCH 
         HSDPA High Speed Downlink Packet Access (concept) 
         MAC Medium Access Controller (protocol layer) 
         MCS Modulation and Coding Scheme 
         NBAP Node B Application Part 
         PDSCH Physical Downlink Shared Channel 
         PO Power Offset 
         RL Radio Link 
         RLC Radio Link Control (protocol layer) 
         RNC Radio Resource Controller (network element) 
         RNSAP Radio Network Subsystem Application Part 
         UE User Equipment (user device) 
       
    
     The power of the HS-DPCCH is set as a power offset (PO). These POs can be defined as POs of the DPCH. In detail, they can be defined as PO relative to DPCCH pilot field. In addition, to guarantee full cell-coverage a CQI repetition scheme can be used whereby periodic CQI&#39;s are sent in the uplink HS-DPCCH. Node B then sends user data on the HS-DSCH according to its own schedule to the users using time and/or code multiplexing to better utilize the available resources also considering UE capability. The Node B prenotifies the UEs of the transport format and resource combination (TFRC), the multi-code set, as well as the HARQ process control on the HS-SCCH two slots in advance of the HS-DSCH. After receiving the user data on HS-DSCH, the UE sends a CQI and/or ACK/NACK on the uplink HS-DPCCH as a feedback signal after a verification time of several slots. Considering the foregoing, especially the new HSDPA-RRM entities (HRQ, packet scheduling, link adaptation) in the Node B, it will be advantageous for the Node B to know the CQI power offset and the POs of ACK/NACK as givens determined either by itself or by the RNSAP/NBAP of the RNC. 
     As described in the  FIG. 5 and 6 , during the RL Setup phase, there are 2 possibilities for accomplishing this end from the outset:
     (1) SRNC decides CQI PO, ACK PO and NACK PO   (2) Node B decides CQI PO, ACK PO and NACK PO   

     In the first case, since SRNC knows the SHO status of UE, based on the SHO situation it can decide the CQI PO, ACK PO and NACK PO. In this case SRNC will assign these POs in the RL Setup Request message during RL setup phase. SRNC will send the same values to UE using proper RRC message. 
     The signaling flow for this example is described in  FIG. 5 . In  FIG. 5 , a serving radio network controller (S-RNC)  500  provides an RL SETUP REQUEST message as a signal on a line  502  from a radio network subsystem application part (RNSAP)  504  to an RNSAP  506  of a drift radio network controller (D-RNC)  508 . The D-RNC  508  processes the RL SETUP REQUEST signal received on the line  502  and provides said RL SETUP REQUEST signal on a line  510  from a Node B application part (NBAP)  512  of the D-RNC  508  to an NBAP  514  of a Node B  516  under D-RNC  508 . The RL SETUP REQUEST signal on the line  502  and on the line  510  may include one or more power offset information elements including a CQI PO, an ACK PO and a NACK PO. In that case, the Node B  516  saves the POs for future use as indicated in a step  518 . The step  518  should therefore be viewed as also representative of a memory within said Node B. The NBAP of Node B  516  then sends an RL setup response message as a signal on a line  520  to the NBAP of the D-RNC  508 . The D-RNC  508  then sends the RL setup response signal on a line  522  from its RNSAP to the RNSAP of the S-RNC  500 . A radio resource control (RRC)  524  of the S-RNC  500  then informs a UE  526  with a proper RRC message signal on a line  528  which is received in the corresponding RRC  530  of the UE  526 . The RRC message includes the CQI PO, the ACK PO and the NACK PO for use by the UE in sending CQI&#39;s, NACK&#39;s and ACK&#39;s on the HS-DPCCH uplink to the Node B. Since the Node B has saved the POs for future use, and it therefore already knows these POs, it can use them in interpreting the CQI, ACK and NACK information sent by the UE to the Node B without having to be in the dark, so to speak. As can be seen by the illustration of  FIG. 1(   b ) as compared to that of  FIG. 1(   a ), the process is made more efficient. It should be realized that a given S-RNC  500  may be in direct communication with an associated Node B, and therefore the steps shown in  FIG. 5  could be carried out without using the D-RNC  508  as an intermediary. For the sake of completeness, however,  FIG. 5  shows the possibility of using a D-RNC intermediate between the S-RNC and the Node B. Consequently, the RL setup request signal on the line  502  can be sent directly to the Node B  516  or via the D-RNC  508 . Likewise, the signaling descriptions shown in  FIGS. 6 ,  7 A,  7 B and  9  should also be understood in this way for signals both in the direction from the S-RNC toward the Node B and in the reverse direction. 
     In the second case, referring now to  FIG. 6 , since Node B knows HSDPA related resource status and can be considered to have better knowledge of HSDPA, it can decide the CQI PO, ACK PO and NACK PO. But in this case Node B doesn&#39;t know whether it is in an HO situation or not. Therefore the SRNC has to give the HO Indication. As described in  FIG. 6 , in an RL Setup Request message is sent by an S-RNC  600  by its RNSAP on a line  602  to an RNSAP  604  of a D-RNC  606  and includes an HO Indication. An NBAP  608  of the D-RNC  606  provides an RL SETUP REQUEST message as a signal with the HO indication on a line  610  to an NBAP  612  of a Node B  614  of the D-RNC  606 . The Node B  614  then decides the POs based on the HO indication and its own measurements and consequent decisions and saves the POs for future use as indicated in a step  616 . After that, the NBAP of the Node B  614  sends an RL setup response message as a signal with the decided PO information elements on a line  618  to the NBAP of the D-RNC  606 . The RNSAP of the D-RNC  606  then sends the RL setup response message on a signal line  620  to the RNSAP of the S-RNC  600 . An RRC  622  of the S-RNC  600  then informs a UE  624  by means of a proper RRC primitive message on a signal line  626  including the CQI, ACK and NACK PO information elements to an RRC  628  of the UE  624 . The UE then uses the PO information in setting the powers of the various CQI, ACK or NACK slots of its HS-DPCCH. 
     And if SRNC is the node to change the Power Offset values then it can use the Synchronized RL Reconfiguration Procedure as described in  FIG. 7   a  to change the POs, once established. One example of this case can be the soft handover (SHO) situation. In an RL Reconfiguration Preparation message on a signal line  7   a   2 , an RNSAP  7   a   4  of an SRNC  7   a   6  can include new CQI PO or/and ACK PO or/and NACK PO or/and and a Node B  7   a   8  shall apply these new values. And if Node B can use the values it will reply with an RL Reconfiguration Ready primitive message on a line  7   a   10  as a positive ACK. If Node B cannot use the values, then it will reply with RL Reconfiguration Failure message. In case of SRNC determination of Power Offsets, to change the POs, it is also possible to use a user plane Frame Protocol (FP) as described in  FIG. 7   b . In this case, in the FP, a proper control frame should be defined or used. For instance like in the DCH FP, it is desirable to define a Radio Interface Parameter Update control frame and deliver these POs in this control frame as shown for instance on a line  7   b   10  from an HS-DSCH FP  7   b   12  of an S-RNC  7   b   14 . An example of such a frame structure is depicted in  FIG. 8 . The name of the control frame or the order of the fields can of course be different than that shown in  FIG. 8 . The important point here is these Power Offsets can be delivered by a UP control frame. In  FIG. 8 , the flag points to whether the corresponding Power Offsets are valid data or not. In the example, Flag bit  1  indicates CQI PO, bit 2  ACK PO and bit 3  NACK PO. If the flag is  1  then the corresponding PO value is valid. Compared to using the control plane, using the user plane is a rather lighter solution. But in the case of using the user plane, the delivery cannot be guaranteed (No response message). Therefore repeatedly sending the same control frame multiple times can be an option. This can make Node B receive the POs with higher probability. 
     If Node B is the node to change these POs and Node B is the node to initiate a PO change procedure, a new message is needed to be defined from Node B to SRNC so that the new message can include new POs. After receiving new POs, SRNC will forward these new POs to the UE. But if Node B is the node to change these POs and SRNC is the node to initiate the PO change procedure (e.g. SRNC changes the POs during SHO), Synchronized RL Reconfiguration Procedure can be used as describe in  FIG. 9 . SRNC  900  sends the RL Reconfiguration Prepare message from an RNSAP  902  on a line  904  to an RNSAP  906  of a D-RNC  908  with HO Indicator, and then an NBAP  910  of a Node B  912  receives the HO indication on a line  914  from an NBAP  916  of the D-RNC  908  and decides  918  new POs and sends them back from the NBAP  910  to DRNC in an RL Reconfiguration Ready message  920 . After receiving same from the D-RNC RNSAP, the SRNC forward those POs to the UE on a line  930  using a proper RRC message. And this whole procedure can be implemented in FP (Frame Protocol). I.e., SRNC can give the HO indication by control frame in FP and Node B will provide CQI PO, ACK PO and NACK PO in a control frame in FP. And also Node B can provide CQI PO, ACK PO and NACK PO with this control frame without SRNC&#39;s request. 
     When HSDPA is implemented CQI Power Offset, ACK Power Offset and NACK Power Offset signaling will be implemented as defined in the specification. During HSDPA service, always UE and Node B shall have same Power Offset (CQI, ACK and NACK) values. Therefore whenever HSDPA is implemented, this feature should be implemented. 
     Although the invention has been shown and described with respect to a best mode embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions in the form and detail thereof may be made therein without departing from the spirit and scope of the invention.