Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0056—Systems characterized by the type of code used
  • H04L1/007—Unequal error protection
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
  • H04B7/2628—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
  • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
  • H04L1/0026—Transmission of channel quality indication
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
  • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
  • H04L1/0028—Formatting
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0072—Error control for data other than payload data, e.g. control data
  • H04L1/0073—Special arrangements for feedback channel
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/08—Arrangements for detecting or preventing errors in the information received by repeating transmission, e.g. Verdan system
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0056—Systems characterized by the type of code used
  • H04L1/0057—Block codes

Definitions

• the present invention relates to a wireless communication system and, more particularly, to a reliable uplink channel quality information (CQI) coding method for HS-DPCCH in HSDPA system for 3GPP.
• CQI channel quality information
• the UMTS Universal Mobile Telecommunications System
• GSM Global System for Mobile communications
• WCDMA Wideband Code Division Multiple Access
• IMT-2000 systems third generation mobile communication systems
• ARIB/TTC of Japan a group of standard developing organizations including ETSI of Europe, ARIB/TTC of Japan, T1 of U.S., and TTA of Korea established the Third Generation Partnership Project (3GPP).
• 3GPP Third Generation Partnership Project
• TSGs Technical Specification Groups
• Each TSG is in charge of approving, developing and managing specifications related to a pertinent area.
• RAN Radio Access Network
• UE User Equipment
• UTRAN UMTS terrestrial radio access network
• the TSG-RAN group consists of one plenary group and four working groups.
• WG1 (Working Group 1) has been developing specifications for a physical layer (Layer 1), and WG2 has been specifying functions of a data link layer (Layer 2) between UE and UTRAN.
• WG3 has been developing specifications for interfaces among Node Bs (the Node B is a kind of base station in the wireless communications), Radio Network Controllers (RNCs) and the core network.
• RNCs Radio Network Controllers
• FIG. 1 illustrates a structure of the UTRAN defined in 3GPP. As depicted in FIG.
• the UTRAN 110 includes at least one or more radio network sub-systems (RNSs) 120 and 130, and each RNS includes one RNC and at least one or more Node Bs.
• RNSs radio network sub-systems
• Node B 122 is managed by RNC 121 , and receives information transmitted from the physical layer of the UE 150 through an uplink channel and transmits a data to the UE 150 through a downlink channel.
• the Node B is considered to work as an access point of the UTRAN from the UE point of view.
• the RNCs 121 and 131 perform functions of allocation and management of radio resources of the UMTS and are connected to a suitable core network element depending on types of services provided to users.
• the RNCs 121 and 131 are connected to a mobile switching center (MSC) 141 for a circuit-switched communication such as a voice call service, and are connected to a SGSN (Serving GPRS Support).
• MSC mobile switching center
• SGSN Serving GPRS Support
• Node 142 for a packet switched communication such as a radio Internet service.
• the RNC in charge of a direct management of the Node B is called a Control RNC (CRNC) and the CRNC manages common radio resources.
• CRNC Control RNC
• the RNC that manages dedicated radio resources for a specific UE is called a Serving RNC (SRNC).
• SRNC Serving RNC
• the CRNC and the SRNC can be co-located in the same physical node. However, if the UE has been moved to an area of a new RNC that is different from SRNC, the CRNC and the SRNC may be located at physically different places.
• RNC is called a lub interface
• an interface between RNCs is called an lur interface
• an interface between the RNC and the core network is called an lu.
• High Speed Data Packet Access is standardization work within the 3GPP for realizing high speed, high-quality wireless data packet services.
• various advanced technologies such as
• AMC Adaptive Modulation and Coding
• HARQ Hybrid Automatic Repeat Request
• FCS Fast Cell Selection
• MIMO Multiple Input Multiple Out
• AMC link adaptation
• UEs in unfavorable positions i.e., close to the cell boundary
• the main benefits of AMC are the higher data rate available for UEs in favorable positions which in turn increases the average throughput of the cell and the reduced interference variation due to link adaptation based on variations in the modulation/coding scheme instead of variations in transmit power.
• ARQ process should be performed along up to the upper layer of the UE and the node B, while in the HSDPA, ARQ process is conducted within the physical layer.
• the key characteristic of the HARQ is to transmit the un-transmitted portion of the encoded block when the NACK (No Acknowledgement) is received from the receiver, which enables the receiver to combine each portion of received codewords into the new codewords with the lower coding rate so as to obtain much coding gain.
• n-channel HARQ Another feature of the n-channel HARQ is that a plurality of packets can be transmitted on n channels even when an ACK/NACK (Acknowledgement/No acknowledgement) is not received unlike in the typically Stop and Wait ARQ which allows the node B to transmit the next packet only when the ACK signal is received from the receiver or to retransmit the previous packet when the NACK signal is received.
• the node B of HSDPA can transmit a plurality of next packets successively even if it does not receive the ACK/NACK for the previous transmitted packet, thereby increasing channel usage efficiency.
• Combining AMC and HARQ leads to maximize transmission efficiency-AMC provides the coarse data rate selection, while HARQ provides fine data rate adjustment based on channel conditions.
• FCS is conceptually similar to Site Selection Diversity Transmission (SSDT).
• SSDT Site Selection Diversity Transmission
• the UE indicates the best cell which should serve it on the downlink, through uplink signaling.
• multiple cells may be members of the active set, only one of them transmits at a certain time, potentially decreasing interference and increasing system capacity. Determination of the best cell may not only be based on radio propagation conditions but also available resources such as power and code space for the cells in the active set.
• MIMO is one of the diversity techniques based on the use of multiple downlink transmit/receiver antennas. MIMO processing employs multiple antennas at both the base station transmitter and terminal receiver, providing several advantages over transmit diversity techniques with multiple antennas only at the transmitter and over conventional single antenna systems. Due to the introductions of these new schemes, new control signals are configured between the UE and the node B in HSDPA.
• HS-DPCCH is a modification to UL DPCCH for supporting HSDPA.
• FIG. 2 shows a frame structure for uplink HS-DPCCH associated with HS-DSCH transmission.
• the HS-DPCCH carries uplink feedback signaling consisted of HARQ-ACK/NACK and channel-quality indicator (CQI).
• Each subframe of length 2ms (3 x 2560 chips) consists of 3 slots, each of length 2560 chips.
• the HARQ-ACK/NACK is carried in the first slot of the HS-DPCCH subframe and the CQI is carried in the second and third slot of the HS-DPCCH subframe.
• the UE is to provide node B with information about the downlink channel quality, i.e., CQI.
• CQI channel quality
• a number of uplink CQI coding methods have been proposed and most proposals assume that the CQI is to be coded into 20 channel bits.
• the CQI coding methods are based on the Transmit Format Combination Indicator (TFCI) coding method of 3GPP specification.
• FIG. 3a shows a (16, 5) TFCI encoder, which is similar to the (32, 10) TFCI encoder in FIG. 3b except that five information bits are used so as to generate (16, 5) TFCI codeword.
• the basis sequences for (16, 5) TFCI code are shown in table 1a and the basis sequences for (32, 10) TFCI code are illustrated in table 1 b.
• the basis sequences for (16, 5) TFCI in Table 1a are included in the basis sequences for (32, 10) TFCI in Table 1 b if the information bits are limited to the first 5 bits and the some 16 output bits are selected from 32 output bits. The common part between two basis sequences is highlighted by shadow in table 1b.
• the CQI coding method is based on the conventional TFCI coding method. The CQI requires 5 information bits and 20 coded bits, i.e. (20, 5) CQI code. Therefore, the (16, 5) TFCI code and (32, 10) TFCI coding method should be modified to fit the required number of bits for CQI coding.
• the (16, 5) TFCI code should be extended to (20, 5) CQI code by adding each basis sequence by 4 bits.
• the (32, 10) TFCI code can be used to generate (20, 5) CQI code through two steps. First, the (32, 10) TFCI code should be expurgated to the (32, 5) modified TFCI code by deleting last 5 basis sequences. Hereinafter the (32, 5) modified TFCI code by deleting last 5 basis sequences is referred to (32, 5) expurgated TFCI code. Secondly, the (32, 5) expurgated TFCI code should be punctured and repeated to meet the (20, 5) CQI code.
• the basis sequences for the (32, 5) expurgated TFCI code are as follows in table 1c.
• the common part of basis sequences between (16, 5) TFCI code and (32, 5) expurgated TFCI code is shadowed.
• the table 1c also include the basis sequences for (16, 5) TFCI code, i.e. table 1a. It means that the generating method based on the (32, 10) TFCI code can be represented by another form of generating method based on the (16, 5) TFCI code, vice versa.
• FIG. 4 illustrates an encoder for generating an extended (16, 5) TFCI code.
• (16, 5) TFCI code is reused with each codeword extended with the four least reliable information bits for (20, 5) CQI code.
• This CQI coding scheme is designed so as to have the optimal minimum distance.
• FIG. 5a illustrates an encoder for generating punctured (32, 5) expurgated TFCI code.
• (32, 5) expurgated TFCI code with puncturing 12 symbols is proposed.
• the puncturing pattern and used basis sequences are as in FIG. 5b.
• the (20, 5) CQI coding scheme based on the (16, 5) TFCI code can be expressed as that based on the (32, 5) expurgated TFCI code, vice versa
• the extended (16, 5) TFCI code and the punctured (32, 5) expurgated TFCI code are commonly expressed as the basis sequences in table 2. It means that the (20,5) CQI coding scheme based on both the (16, 5) TFCI and (32, 5) expurgated TFCI code is to decide what the basis sequence pattern is in the blank in table 2.
• the basis sequence part which is the same as 3GPP technical specifications will be omitted for convenience.
• FIG. 6 illustrates another encoder for generating extended (16, 5)
• Mj, 4 is the most significant bit (MSB). This arrangement gives significant extra protection to the MSB, and a little more robustness to the next most significant bit.
• the conventional CQI coding schemes and their performances are varied according to the extended parts of basis sequence table. In this approach, to select optimum CQI coding scheme means just to find optimum extended part of the basis sequence table.
• the above CQI coding schemes are developed in consideration of BER performance and unequal error protection (RMS error reduction) but system throughput.
• the coding schemes have tradeoffs between BER and unequal error protection.
• the first and second CQI coding schemes are superior to that of the third one.
• the third CQI coding scheme is superior to those of the first and second ones.
• the present invention has been made in an effort to solve the above problem. It is an object of the present invention to provide a method for generating basis sequences for CQI coding capable of maximizing a system throughput.
• the channel quality information (CQI) coding method comprises (a) creating first basis sequences for generating (32, 5) expurgated TFCI code from (32, 10) TFCI code, (b) puncturing each of the (32, 5) expurgated TFCI codes in a predetermined bit pattern in order to maximize system throughput, (c) repeating a predetermined bit of each (32, 5) expurgated TFCI code for predetermined times in order to maximize system throughput, and (d) encoding 5 information bits into CQI codes using a second basis sequences generated through (b) and (c).
• Each (32, 5) expurgated TFCI code is punctured as many as 16 bits in order of 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, and 30 th bits, and a 31 st bit of the (32, 5) expurgated TFCI code is repeated 4 times.
• the first basis sequences are already shown in table 1c.
• the second basis sequences are as in following table:
• the channel quality information (CQI) coding method comprises inputting 5 information bits, generating 32 bit sub-codes with the information bits using a basis sequences, generating 20 bit codewords by puncturing 16 bits from each of the sub-codes in a predetermined bit pattern and repeating a predetermined bit of the sub-code.
• the sub-codes are punctured 16 bits in order of 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, and 30 th bits and 31 st bit is repeated 4 times.
• the resultant basis sequences are represented by
• Mi ,0 101010101010100000
• Mi, ! 01100110011001100000
• M i ⁇ 2 00011110000111100000
• M i ⁇ 3 00000001111111100000
• the channel quality information (CQI) coding method comprises (a) obtaining first basis sequences from (16, 5) TFCI code, (b) extending basis sequences to (20,5) CQI code in a predetermined pattern in order to maximize system throughput, (c) encoding 5 information bits into CQI codes using a second basis sequences generated through (a) and (b).
• the second extended basis sequences are the same as the upper table.
• the channel quality information (CQI) coding method comprises (a) encoding 5 information bits into (16, 5) TFCI codes using (16, 5) TFCI basis sequences (b) repeating the MSB of information bits 4 times in order to maximize system throughput.
• FIG. 1 is a conceptual view showing a structure of the UMTS radio access network (UTRAN);
• FIG. 2 is a drawing illustrating a frame structure for uplink HS- DPCCH associated with HS-DSCH transmission
• FIG. 3a is a schematic block diagram illustrating a (16, 5) TFCI encoder
• FIG. 3b is a schematic block diagram illustrating a (32, 10) TFCI encoder
• FIG. 4 is a schematic block diagram illustrating an encoder for generating a conventional (20, 5) CQI code based on the (16,5) TFCI code;
• FIG. 5a is a schematic block diagram illustrating an encoder for generating conventional (20, 5) CQI code based on the expurgated (32, 5) TFCI code;
• FIG. 5b is a table showing a puncturing pattern and used basis adapted to the encoder of FIG 5a;
• FIG. 6 a schematic block diagram illustrating another encoder for generating (20, 5) CQI code by extending (16, 5) TFCI code;
• FIG. 7a is a schematic block diagram illustrating an encoder for generating
• FIG. 7b is a table showing a puncturing pattern, repetition pattern, and used basis adapted to the encoder of FIG. 7a;
• FIG. 8a is a schematic block diagram illustrating an encoder for generating (20, 5) CQI code according to a second embodiment of the present invention
• FIG. 8b is a table showing a puncturing pattern, repetition pattern, and used basis adapted to the encoder of FIG. 8b;
• FIG. 9a is a schematic block diagram illustrating an encoder for generating (20, 5) CQI code according to a third embodiment of the present invention
• FIG. 9b is a table showing a puncturing pattern, repetition pattern, and used basis adapted to the encoder of FIG. 9a.
• FIG. 7a is a block diagram illustrating an encoder for generating (20, 5) code according to a first embodiment of the present invention and FIG. 7b is a table for illustrating how the encoder of FIG. 7a generate the (20, 5) code.
• the encoder linearly combines the information bits with basis sequences so as to generate a (32, 5) expurgated TFCI code.
• the expurgated TFCI code of 32 bit length is punctured by 13 bits in a puncturing pattern (0, 2, 4, 5, 6, 8, 9, 10, 11 , 12, 13, 14, and 30 th bits) and the 31 st bit is repeated one time such that the code word of 20 bit length is obtained.
• the basis sequences are M
• the basis sequences generated according to the first embodiment are as following in table 4. In other aspect of the first embodiment is to construct basis sequences by extending from (16, 5) TFCI code to the basis sequence of table 4. ⁇ table 4>
• FIG. 8a is a block diagram illustrating an encoder for generating (20, 5) code according to a second embodiment of the present invention and FIG. 8b is a table for illustrating how the encoder of FIG. 8a generate the (20, 5) code.
• the encoder linearly combines 5 inputted information bits with basis sequences so as to generate a (32, 5) expurgated TFCI code.
• the expurgated TFCI code of 32 bit length is punctured by 14 bits in a puncturing pattern (0, 1 , 2, 4, 5, 6, 8, 9, 10, 11 , 12, 13, 14, and 30 th bits) and the 31 st bit is repeated two times such that the code word of 20 bit length is obtained.
• the basis sequences generated according to the second embodiment of the present invention are as following in table 5. In other aspect of the second embodiment is to construct basis sequences by extending from (16, 5) TFCI code to the basis sequence of table 5. ⁇ table 5>
• FIG 9a is a block diagram illustrating an encoder for generating (20, 5) code according to a third embodiment of the present invention
• FIG. 9b is a table for illustrating how the encoder of FIG. 9a generate the (20, 5) code.
• the encoder linearly combines 5 inputted information bits with basis sequences so as to generate a (32, 5) expurgated TFCI code.
• the expurgated TFCI code of 32 bit length is punctured by 16 bits in a puncturing pattern (0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, and 30 th bits) in order to maximize the system throughput and the 31 st bit is repeated 4 times in order to maximize the system throughput such that the code word of 20 bit length is obtained.
• the basis sequences generated according to the third embodiment of the present invention are as following in table 6. ⁇ table 6>
• the channel quality information (CQI) coding method comprises (a) obtaining first basis sequences from (16, 5) TFCI code, (b) extending basis sequences to (20, 5) CQI code in a predetermined pattern in order to maximize system throughput, (c) encoding 5 information bits into CQI codes using a second basis sequences generated through (a) and (b).
• the second extended basis sequences are the same as table 6.
• the channel quality information (CQI) coding method comprises (a) encoding 5 information bits into (16, 5) TFCI codes using (16, 5) TFCI basis sequences (b) repeating the MSB of information bits 4 times.
• the CQI coding schemes of the embodiments and the conventional ones were simulated and compared with respect to BER, RMS error, and system throughput for selecting optimum CQI coding scheme. Since there is a trade-off between BER and RMS error, the system throughput is considered as a criterion.
• the conventional CQI coding schemes characterized in table 2 and table 3 are referred as C1 and C2.
• the performance gap between the worst and the best is approximately 0.5 dB at BER 10 "5 .
• the root- mean-square (RMS) error as the criterion is introduced.
• the RMS error means the root mean square of difference between transmitted codewords and received codewords.
• the order of the RMS error reduction performance is as follows. Embodiment 3 > C2 > embodiment 2 > embodiment 1 > C1
• the performance gap between the worst and the best is approximately 1.5 at -3dB EbNo/Slot.
• the system throughput is calculated using simplified system level simulation. And the conventional analytic system level simulator and uplink
• the throughput of BER performance is as follows.
• Embodiment 3 > C2 > embodiment 2 > embodiment 1 > C1 ( ⁇ r better ,,, worse - )
• the performance gap between the worst and the best is approximately 79kbps at 3dB.
• the CQI coding schemes are classified with respect to the extended parts of the basis sequence tables and the system throughput is introduced as a criterion for evaluating the CQI coding schemes because there is a trade-off between BER and RMS error. Moreover, during the system throughput simulation, both BER and RMS error effect are already considered together. Also, since HSDPA system has been designed in order to increase the system throughput, the third embodiment of the present invention, which shows the best system throughput in the simulation, can be the optimum CQI coding scheme for HS-DPCCH.

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