Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W56/00—Synchronisation arrangements

Definitions

• the present invention relates to a method for high speed downlink packet access
• HSDPA high-speed data user equipments
• TD-SCDMA time division multiple access
• TD-SCDMA time division multiple access
• HSDPA High Speed Downlink Packet Access
• AMC Adaptive Modulation and Coding
• HARQ Hybrid Automatic Retransmission Request
• HSDPA technology further incorporates a Media
• MAC-hs Access Control-High Speed Downlink Packet Access entity
• the MAC-hs entity is located in a Node B, such that the control of the information retransmission that would otherwise have to be made on the network side can be carried out in the Node B directly. Still further,
• HSDPA technology has introduced a High Speed Downlink Shared Channel (HS-DSCH) for transmitting user data, and introduced, in a physical layer, a High Speed Shared Control Channel for the HS-DSCH (HS-SCCH) and a High Speed Shared Information Channel for the HS-DSCH (HS-SICH), thereby being capable of implementing directly and rapidly information communication between a UE and the Node B.
• HSDPA technology requires an attendant dedicated channel (A-DCH) for transmitting signaling information and maintaining synchronization of a uplink when data are transmitted via the HS-DSCH.
• A-DCH dedicated channel
• HSDPA technology the introduction of additional channel HS-SCCH ,
• HSDPA technology was originally developed for providing high speed data services for a small number of UEs, there exists an earnest need for improving the HSDPA technology with more and more low- and medium-speed services such as VoIP popping out.
• the purpose of the present invention is to provide a method for implementing HSDPA (MU-HSDPA, Multi-User HSDPA) for a large number of low- and medium-speed data UEs over a single carrier frequency in a time division synchronous code division multiple access system.
• the method of the present invention effectively reduces system signaling overhead due to HSDPA, and increases the number of on-line
• each carrier frequency may support at least 48 Erlangs.
• the present invention provides a method for HSDPA for a large number of low- and medium-speed data UEs over a single carrier frequency in a time division synchronous code division multiple access system.
• the method is adapted for use in a mobile communication system consisting of a base station and a UE.
• the base station includes a media access control-high speed downlink packet access entity (MAC-hs).
• MAC-hs media access control-high speed downlink packet access entity
• a single carrier or multiple carriers is/are used for data transmission between the base station and the UE.
• the HSDPA is introduced in 3GPP Release 5 Specification in which HSDPA UEs maintain downlink synchronization and transmit RRC messages over the A-DCH channels.
• the method comprise the following steps: adding a common synchronization signaling channel (CSSCH) over which SS signaling of all UEs are to be transmitted; channel-coding to the SS signaling to be carried over the common synchronization signaling channel; transmitting the channel-coded SS signaling over the common synchronization signaling channel instead of transmitting the channel-coded SS signaling over attendant dedicated channels (A-DCHs) as defined in 3 G 3GPP Release 5 Specification, and transmitting the RRC messages over HS-DSCH channels instead of transmitting the RRC messages over the A-DCHs as defined in 3 G 3GPP Release 5 Specification.
• a network assigns a synchronization number to each UE when the UE establishes a connection, and informs the UE of the synchronization number by sending a RRC Connection Setup message.
• the UE receives the synchronization number and reads SS signaling for the UE from a respective code block carried over the CSSCH channel in each subsequent sub-frame.
• a CSSCH channel is introduced in an embodiment of the invention. Therefore, HSDPA UEs no longer maintain the downlink synchronization by the SS signaling over the A-DCHs, rather, the SS signaling of all
• the UEs are altogether transmitted over the CSSCH channel.
• the RRC messages are transmitted over the HS-DSCH channels (in 3 G 3GPP Release 5 Specification, RRC messages are transmitted over the A-DCHs).
• a channel coding is applied to SS signaling carried over the common synchronization signaling channel.
• a modulation indication channel is added in 3G 3GPP Release 5 Specification.
• the modulation indication channel is used for indicating which UEs are transmitting data in a current sub-frame and in which mode the HS-SCCH channels of these UEs are modulated.
• Feedback information corresponding to a HS-SCCH such as ACK/NAK and CQI information, is sent via the shim layer between a physical layer and a MAC layer instead of via a HS-SICH.
• a HS-SCCH signaling format as defined in 3GPP Release 5 Specification is compressed. Based on service rates and decisions of whether or not data packets are retransmitted, the data packets are divided into three types: a low-speed newly transmitted data packet with rate less than 16Kbps, a high-speed newly transmitted data packet and a retransmitted data packet.
• the HS-SCCH signaling for the three types of date packets are compressed respectively, and thus the compressed HS-SCCH signaling for all data other than retransmitted data can be transmitted over one SF 16 code channel.
• Feedback information corresponding to a HS-SCCH such as ACK/NAK and CQI information, is sent via the shim layer between a physical layer and a MAC layer instead of via a HS-SICH.
• MICH Modulation Indication Bitmap
• UEI UE Indicator
• RTN Re-Transmit Number
• MICH Modulation Indication Bitmap
• UEI UE Indicator
• RTN Re-Transmit Number
• MICH modulation indication channel
• a MICH burst is composed of 32-bit information.
• the MICH channel is formatted as shown in Fig. 1, and will be described hereinafter in details in conjunction with embodiments.
• the HS-SCCH channel indicated by the MICH channel is always situated in time slot 6 of the same sub-frame, and the HS-DSCH channel identified by the HS-SCCH signaling is situated in the downlink time slot prior to time slot 6 of the next sub-frame.
• the timing sequence regarding the MICH, HS-SCCH and HS-DSCH channel is shown in Fig. 2.
• Fig. 2 exemplifies three service time slots for both a uplink and a downlink.
• the HS-DSCH channel indicated by the HS-SCCH channel in sub-frame n is located in time slot 4 and time slot 5 of sub-frame n+1.
• CSSCH Common Synchronization Signaling Channel
• A-DCHs are cancelled from the 3GPP Release 5 Specification.
• the A-DCHs are generally used to transmit RRC signaling and physical layer SS signaling.
• RRC messages are seldom transmitted. From the view of code resources, it is a great waste of resources to reserve separately a code channel for a RRC message.
• A-DCHs are cancelled.
• a RRC message is transmitted from a UE over the HS-DCSH channel corresponding to the UE.
• the SS signaling from various UEs are transmitted together over the CSSCH channel.
• a special transmission block is used for transmitting feedback information corresponding to a HS-SCCH.
• the feedback information includes HARQ-Id, ACK/NAK and Quantity Indicator.
• the formats of the transmission block will be described hereinafter in details in conjunction with embodiments.
• a HS-SCCH signaling format as defined in 3GPP Release 5 Specification is compressed and all data packets are divided into three types: a low-speed newly transmitted data packet with rate less than 16Kbps, a high-speed newly transmitted data packet and a retransmitted data packet, based on a service rate and a decision of whether or not the data packets are retransmitted.
• the three types of packets have respective HS-SCCH signal formats.
• the HS-SCCH signaling formats compressed will be described hereinafter in details in conjunction with embodiments.
• all sub-frames are divided into four groups of sub-frames based on a remainder of a sub-frame number of a sub-frame mod 4.
• the network assigns one or more identification pairs I to the UE based on a service rate of the UE.
• various UEs are identified by the identification pairs I of the UEs instead of 16 bit UE-IDs in HS-SCCH signaling, and information associated with the UEs is obtained from the MICH channel.
• the present invention has achieved the following advantageous effect:
• the SS signaling in various physical channels are concentrated in the CSSCH channel and moreover are subjected to channel coding before transmission. This greatly reduces bit error rate when the signal-noise ratio is low. If a UE detects any bit error but cannot correct it when the signal-noise ratio is relatively low, the SS signaling of the corresponding sub-frame is discarded, such that failed synchronization caused by an incorrect SS signaling is avoided.
• a code channel to be occupied by the HS-DSPCH channel is pre-configured.
• a single carrier frequency is used to plan the network.
• code resources can not be shared between voice services and HSDPA data services.
• the code resources for voice services is insufficient, a call loss may occur even though the transmission rate of HSDPA data services is relatively low, because no code resource is shared between voice services and HSDPA services.
• low-speed voice services can be transmitted with HSDPA by VoIP, that is, voice services and data services may share the code resources.
• transmission rates for various services may be dynamically adjusted.
• Data services can have their transmission rates adjusted; voice services may have their channel codes adjusted by adjusting the coding rate of AMR. Therefore, when a service (e.g., voice switching), to which a higher priority is given, is requested, that service with a higher priority may occupy the bandwidth and channel code of the service with a lower priority, thereby reducing possibility in call loss and handover call drop.
• a service e.g., voice switching
• the uplink and downlink time slots of TD-SCDMA are configurable. However, to avoid interferences between a uplink and a downlink, a switching point between the uplink and downlink in two adjacent co-frequency cells must be configured to be the same. Since the uplink and downlink rates for pure voice services are symmetrical but the uplink and downlink rates for data services are asymmetrical, it is therefore difficult to set the same switching point between a uplink and a downlink for all co-frequency cells.
• various low-, medium- and high-speed services over a plurality of channels may be simultaneously carried over a single carrier frequency. Due to a transmission for integrated data services and voice services, a reasonable proportion between uplink and downlink transmission rates may be achieved to facilitate a more flexible uplink and downlink configuration of time slots.
• HSDPA may be used for supporting voice services by VoIP and thus implements transition from all CS domains to PS domains over the air interface. Thereafter, a core network will no longer maintain the equipment for CS domain to reduce the operation and maintenance cost.
• Fig. 1 shows an encoding format of a MICH channel.
• Fig. 2 shows a timing sequence of a MICH channel, HS-SCCH channel and HS-DSCH channel.
• Fig. 3 is Format 1 of a shim layer added between a physical layer and a MAC layer.
• Fig. 4 is Format 2 of a shim layer added between a physical layer and a MAC layer.
• Fig. 5 shows an allocation of the HS-DSCH code channels. Each code channel is identified with a UE ID, which is calculated according to an equation 4*g+u. The active UEs in the current sub-frame are those indicated as 25, 27, 28, 31, 35, 36, and retransmitting UEs are those indicated as 1, 4 and 13.
• SSl and SS2 represent the CSSCH channel. Sign '-' indicates that the code channel carries no data.
• MICH modulation indication channel
• the modulation indication channel always occupying a code in time slot 0 with
• all modulation indication channels are assigned to a main carrier frequency.
• the modulation indication channel carries a 32-bit burst as shown in Fig. 1, which is transmitted in a wireless sub-frame after being subject to the following steps: CRC coding step: encoding information with 8-bit CRC coding;
• Convolution coding step encoding information with 1/2 convolution coding with length-9 so that the data length of the encoded data extends to 96 bits;
• Rate matching step subjecting the encoded data to a 8-bit punching process, because a data burst includes 88 bits;
• Interleaving step performing interleaving process using an interleaver with "11 rows x 8 columns".
• the 32-bit information carried over the modulation indication channel includes Modulation Indication Bitmap (MIB), UE Indicator (UEI) and Re-Transmit Number (RTN).
• MIB Modulation Indication Bitmap
• UEI UE Indicator
• RTN Re-Transmit Number
• MIB domain contains 16 bits for indicating the modulation modes of 16 SF 16 codes in time slot 6 of the current sub-frame. "0" represents QPSK, and "1" represents 16QAM. A UE can know the modulation mode of each of code channels in time slot 6 by reading the MEB domain of the modulation indication channel, and can thus correctly decode the data carried in time slot 6.
• UEI is a 12-bit bitmap for indicating which UEs are in an active state in the current sub-frame (i.e., data is being transmitted in the current TTI).
• all of sub-frames are divided into four groups of sub-frames based on the remainder of sub-frame number mod 4.
• the group number g of a sub-frame ranges [0, 3] and the in-group UE ID u ranges [1, 12].
• the network assigns one or more identification pairs I to the UE based on the service rate of the UE.
• the UE determines its own information of interest in the MICH channel based on its own identification pair I.
• UE ED u equals to 3 signifies that the 3 rd bit from the left of UEI of the MICH channel is the indication bit of the UE. If this bit is 1, there is data newly transmitted to the UE in the current TTI, and the UE should read HS-SCCH signaling from a corresponding code channel of time slot 6 in the current sub-frame.
• the UEI also determines the position of the code channel occupied by the
• HS-SCCH signaling corresponding to the UE in time slot 6 If m bits counted from the 1 st bit from the left of UEI through u* bit are set to 1, the m* SF 16 code channel in time slot 6 is the one to carry the HS-SCCH signaling corresponding to the UE.
• MU-HSDPA follows the HARQ mechanism of HSDPA. When it is necessary to retransmit data of a UE, it is necessary as well to transmit a related HS-SCCH signaling in time slot 6.
• MU-HSDPA is designed to include two Retransmit Sets. If the in-group UE ID u is an odd number, the UE corresponds to Retransmit Set I. If the in-group UE DD u is an even number, the UE corresponds to Retransmit Set II. RTN-I and RTN-II are used to indicate how many UEs in each Retransmit Set are retransmitting data in the current TTI.
• the UEs in Retransmit Set I should read and find its own HS-SCCH signaling from the (M+l)" 1 to (M+Rl +Rl') 111 SF16 code channels in time slot 6, and the UEs in Retransmit Set II should read and find its own HS-SCCH signaling from the (M+Rl +Rl'+l)* to (M+Rl +Rl'+Rl+Rl'f SF16 code channels in time slot 6.
• R2 represents the number of retransmitting UEs in Retransmit Set II in the current sub-frame
• R2' represents the number of the UEs using QPSK in the R2 number of UEs.
• the HS-SCCH signaling corresponding to a retransmitting UE contains the UE-ID that can identify the UE.
• the newly transmitted data differs from the retransmitted data in that the newly transmitted data of the UE with the group number g of a sub-frame is sent only in the sub-frame No. 4n+g, whereas the retransmitted data may be sent in any sub-frame.
• CSSCH common synchronization signaling channel
• HSDPA UEs maintain downlink synchronization by the SS signaling in A-DCH channels.
• a physical channel common synchronization signaling channel is introduced in the present invention, whereby the SS signaling that would otherwise have to be transmitted over various A-DCH channels are transmitted together in the common synchronization signaling channel.
• a channel coding is applied to the SS signaling carried over the CSSCH channel.
• a number of coding modes can be used for the channel coding, and preferably a second order (32, 10) or (16, 5) Reed-Muller coding is used.
• the data format of the CSSCH channel will be described below, for example, in terms of a second order (16, 5) Reed-Muller coding.
• SS signaling sent in each TTI (5 ms) has three kinds of possibilities, i.e., "moving up 1/8 chip” (indicated by 'f), “moving back 1/8 chip” (indicated by 'J,') and "no adjusting” (indicated by '-').
• the relationship between a 5-bit code block and the synchronous adjustment signaling of the three UEs is shown in the table below:
• MU-HSDPA user data capacity per a single carrier frequency is a 48-Erlang. If (16, 5) second order Reed-Muller coding is used, 48 UEs are divided into 16 groups of UEs, each containing 3 UEs. The SS signaling of each group of UEs contains 5 bits, and changes to 16 bits after being subject to the (16, 5) second order Reed-Muller coding. Therefore, the SS signaling of 48 UEs demands in total up to 256 bits. All of these SS information may be carried by using three SF 16 code pairs.
• the network assigns a synchronization number to the UE, and informs the UE of the synchronization number by sending a RRC Connection Setup message.
• the UE reads its corresponding SS signaling from the respective code block carried over the CSSCH channel in each of subsequent sub-frames. For example, when the synchronization number assigned to a UE is 5, it means that the SS signaling of the UE is situated in the second group. The UE therefore reads only the second code block (each code block contains 16 bits) in the CSSCH channel at a time, wherein the second SS signaling in the code block is the SS signaling corresponding to the UE.
• the code channel occupied by the CSSCH may be set in service time slots (TS1-TS6) and is subject to a broadcast beamforming.
• the transmission power of the code channel is set at the time of establishing the cell and is not subject to a power control.
• each UE is provided with an attendant dedicated channel which is used for transmitting RRC signaling and SS signaling.
• an attendant dedicated channel which is used for transmitting RRC signaling and SS signaling.
• a RRC message is seldom transmitted. Therefore, from the view of code resources, it is a great waste of resources to reserve separately a code channel for a RRC message.
• the attendant dedicated channel is cancelled.
• the RRC message of a UE is transmitted in a shared channel corresponding to the UE.
• the SS signaling is sent in the common synchronization channel newly introduced.
• HS-SICH For HSDPA, there is an uplink HS-SICH channel for each HS-SCCH channel.
• the HS-SICH channel indicates whether and how the data transmitted over the HS-DSCH channel should be retransmitted.
• the HS-SICH channel carries information of 8 bits, 1 bit for ACK/NACK and 7 bits for CQI.
• the information of 8 bits occupies a code channel with SF 16, resulting in a great waste of resources.
• a shim layer is added between the physical layer and the MAC layer to transfer ACK/NACK and CQI.
• the shim layer has two formats. Format 1 : adding 4 bits before a MAC PDU, 3 bits for HARQ-ID and 1 bit for
• Format 2 adding 11 bits before a MAC PDU, 3 bits for HARQ-ID, 1 bit for ACK/NACK, and 7 bits for CQI (Channel Quality Indicator), as shown in Fig. 40.
• HARQ-ID and ACQI in these formats are defined similarly as in 3GPP Release 5 Specifications.
• the shim layer is located only in a uplink data DCH.
• a UE utilizes the TFCI in a uplink DPCH to indicate whether the shim layer is included in the uplink data DCH, and what format of the shim layer is, if any.
• Node B sends the MAC PDU to
• the HS-SCCH as a shared channel must be modulated with QPSK mode.
• Each HS-SCCH channel occupies two SF 16 code channels for its lengthy coding format.
• the downlink signaling transmitted over the HS-SCCH channel is changed from a common channel signaling to a channel associated signaling.
• the downlink SH-SCCH signaling and the downlink data are modulated in the same manner which is determined by a UE by reading the MIB signaling of the MICH channel.
• the HS-SCCH signaling of each UE forms a signaling code block.
• all HS-SCCH signaling code blocks are always situated in time slot 6. The UE first determines, based on the UEI in the MICH channel and the current sub-frame number, whether there is data newly transmitted to itself in the current sub-frame.
• the UE determines, based on the UEI in the MICH channel, the code channel occupied by its own HS-SCCH signaling in time slot 6, and moreover determines, based on the MIB in the MICH channel, the modulation mode of the code channel. Upon completing the above determinations, the UE may interpret its own HS-SCCH signaling from the code channel. If the UE is waiting for retransmission of data, in addition to the newly transmitted data of interest, the UE further pay attention to the data retransmitted. All UEs may be divided into two Retransmit Sets based on whether the assigned in-group UE ID is an odd or even number.
• the UE When receiving the retransmitted data, the UE first determine, based on the MIB, UEI, RTN-I and RTN-II in the MICH, the modulation mode of its HS-SCCH signaling and the range of its code channel, interprets the HS-SCCH signaling from a corresponding position, and determines its own HS-SCCH signaling based on the UE-ID in HS-SCCH signaling.
• the original HS-SCCH signaling format is compressed.
• either signaling of newly transmitted data or signaling of retransmitted data takes the same format in HS-SCCH channel.
• the signaling has the following three different formats: low-speed (less than 16Kbps) newly transmitted data service format, high-speed newly transmitted data service format and retransmitted data service format based on the service transmission rate and whether or not the data concerned is retransmitted.
• No UE-ID is included in the low-speed newly transmitted data service format and the high-speed newly transmitted data service format.
• a UE determines, based on its own identification pair I and the UEI signaling in the MICH, whether the current sub-frame contains its own HS-SCCH, and where its own HS-SCCH is located in time slot 6.
• a corresponding UE is determined based on the UE-ID in HS-SCCH signaling.
• the code channel of HS-SCCH signaling is always situated in a lower code channel position of time slot 6, while the user data are arranged in an upper code channel position of time slot 6 and in the downlink time slots, excluding time slot 6, of the subsequent sub-frames.
• the user data are distributed in various time slots in a serpentine manner (as shown in Fig. 5) to equalize the power of each time slot and reduce interference.
• a UE judges the position of its data in the sub-frame based on the "resource allocation" domain.
• the newly transmitted low-speed data service, the newly transmitted high-speed data service and the retransmitted data service respectively have differently formatted "resource allocation domain":
• the 7-bit Start Point is used to indicate the initial code channel position of the user data in a sub-frame.
• the 3-bit length is used to indicate the number of the code channels occupied consecutively by the data of the UE.
• RRC-included ID indicates whether or not RRC signaling information is included in the transmitted data.
• Transmission combination format/transmission block size
• this parameter When a low-speed newly transmitted data (mainly new voice service) is transmitted, this parameter contains 4 bits for indicating the transmission combination format. This parameter may support 8 coding rates from AMR4.7 Kbps to AMR 12.2 Kbps. When new data service and retransmission service are transmitted, this parameter contains 6-bit information for indicating the transmission block size.
• This parameter is the same as that of 3GPP Release 5 HSDPA, i.e., 3-bit.
• This parameter is the same as that of 3GPP Release 5 HSDPA, i.e., 3 -bit.
• This parameter is the same as that of 3GPP Release 5 HSDPA, i.e., 2-bit.

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• 2007
  • 2007-04-06 CN CNB2007100213173A patent/CN100521688C/zh not_active Expired - Fee Related
• 2008
  • 2008-04-07 WO PCT/CN2008/000696 patent/WO2008122206A1/en active Application Filing

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