METHOD AND APPARATUS FOR ENCODING FEEDBACK SIGNAL The present application is a divisional application from Australian patent Application No. 2009342391, the entire disclosure of which is incorporated herein by reference. FIELD OF THE INVENTION 5 The present invention relates to the field of communication technologies, and in particular, to a method and apparatus for encoding feedback signals. BACKGROUND OF THE INVENTION In a physical layer hybrid automatic repeat request (HARQ) procedure, a User Equipment (UE) monitors a High Speed-Shared Control Channel (HS-SCCH). If no data is received, the UE 0 has no action, which can be understood that: the UE does not transmit information to a base station (a Node B), and in this case, feedback information acquired by the Node B is Discontinuous Transmission (DTX) information. If data is received, data on a High Speed-Downlink Shared Channel (HS-DSCH) is detected according to control channel information. If the received data is correct, acknowledgement (ACK) information is transmitted to the Node B; if the received data is 5 incorrect, Negative acknowledgement (NACK) information is transmitted to the Node B. The DTX, ACK, and NACK information are uniformly referred to as hybrid automatic repeat request-acknowledgement (HARQ-ACK) information. After being encoded, the HARQ-ACK information is further transmitted to the Node B through an uplink High Speed-Dedicated Physical Control Channel (HS-DPCCH). The Node B receives and translates the feedback information. If the 20 feedback information is ACK, new data is transmitted; if the feedback information is NACK, the data is re-transmitted; if the feedback information is DTX, the new data is re-transmitted. In the Third Generation Partnership Project (3GPP) standards, a Dual Carrier-High Speed Downlink Packet Access (DC-HSDPA) technology is introduced for improving user experience. Based on the technology, several HARQ-ACK encoding solutions are provided in the prior art, and 25 are specifically illustrated as follows. In the Release 5 (R5) version of 3GPP TS25.212, a single-carrier encoding solution is provided. In this case, a total of three feedback signals are required to be transmitted, namely, ACK, NACK, and DTX, in which ACK and NACK are required to use codewords, as shown in Table 1-1: 1 Table 1-1 Single-Carrier HARQ-ACK Encoding Solution ACK 1 1 1 1 1 1 1 1 1 1 NACK 0 0 0 0 0 0 0 0 0 0 In the Release 8 (R8) version of the 3GPP TS25.212, a dual-carrier encoding solution is provided, and the solution requires nine feedback signals, in which eight codewords are used (DTX 5 does not use any codeword), as shown in Table 1-2: Table 1-2 Dual-Carrier HARQ-ACK Encoding Solution The UE only detects data block on a primary carrier. ACK 1 1 1 1 1 1 1 1 1 1 NACK 0 0 0 0 0 0 0 0 0 0 The UE only detects a data block on an secondary carrier. ACK 1 1 1 1 1 0 0 0 0 0 NACK 0 0 0 0 0 1 1 1 1 1 The UE detects data blocks on both of primary and secondary carriers. Primary carrier Secondary carrier feedback signal feedback signal ACK ACK 1 0 1 0 1 0 1 0 1 0 ACK NACK 1 1 0 0 1 1 0 0 1 1 NACK ACK 0 0 1 1 0 0 1 1 0 0 NACK NACK 0 1 0 1 0 1 0 1 0 1 Currently, researches about Ternary Cell (TC) technologies have not been started yet, and the inventors find by studying the prior art that: if the prior art is adopted to solve the feedback problem 0 in TC, the most direct method is to adopt three code channels, each carrier uses one code channel, and then the encoding solution as shown in Table 1-1 is adopted; or two code channels are adopted. One carrier uses the encoding solution as shown in Table 1-1, and the other two carriers use the encoding solution as shown in Table 1-2. Disadvantages of the two methods lie in that, excessive power is required to be consumed, the generally consumed power is 2 to 3 times of that for the 15 single carrier, and a system Cubic Metric (CM) value is increased, thus affecting the system performance. SUMMARY OF THE INVENTION The present invention is direct to methods and apparatuses for encoding feedback signals to implement that feedback signals of three carriers are encoded with a single code channel. 20 According to one aspect of the present invention, a method for encoding feedback signals is 2 provided. The method may include: encoding feedback signals of three carriers to output a bit sequence; and transmitting the bit sequence on an uplink HS-DPCCH, in which the encoding the feedback signals of the three carriers includes: mapping the feedback signals 5 of the three carriers into a codeword selected from a codebook, in which the codebook comprises codewords G1 to G16 and H1 to H10, in which code distance relationships of the codewords in the codebook are as shown in Table 1-3: Table 1-3 GI G2 G3 G4 G5 G6 G7 G8 G9 GO Gil Gi2 G13 G14 G15 GI HI H2 H3 H4 H5 H6 H7 H8 H9 HIO GI 0 6 6 6 4 6 4 6 4 6 6 6 4 4 4 10 4 4 4 4 6 4 6 4 6 G2 6 [ 6 6 6 4 4 6 4 6 6 6 4 6 4 4 4 0 4 4 4 6 6 4 6 4 G3 6 60 6 4 6 6 4 44 6 6 4 4 6 4 4 410 4 4 4 6 4 G4 6 6 6 0 4 6 4 6 6 4 6 6 4 4 4 6 4 4 106 4 6 4 6 G5 6 6 4 4 0 4 6 6 6 6 6 4 6 6 4 4 4466i064444 G6 4 5 6 6 4 0 6 6 6 6 6 4 4 6 6 6 6 4 4 6 10 4 4 4 4 G7 6 5 6 4 6 6 0 4 64 6 4 6 4 6 4 4 6 4 6 4 106 4 4 G8 4 6 4 6 6 6 4 0 64 6 4 4 6 4 6 6 4 6 4 4 6 0 4 4 G9 6 4 4 6 6 6 6 6 4 6 4 6 4 4 6 4 6 6 4 4 4 4 4 10 6 31( 4 6 6 4 6 6 6 6 4 0 6 4 4 6 6 4 6 4 4 6 4 4 4 4 6 10 GII 6 6 6 6 6 6 6 6 6 6 0 6 6 6 6 6 4 4 4 4 4 4 4 4 4 4 G12 6 6 66 4 4 4 4 4 4 6 0 6 6 6 6 4 4 4 4 6 6 6 6 6 G3 6 4 4 4 6 4 6 4 6 4 6 6 0 6 6 6 4 6 6 6 4 6 4 6 4 6 31 6 4 4 4 6 4 4 6 4 6 6 6 0 6 6 6 4 6 6 6 6 4 G15 4 4 6 4 4 6 6 4 4 6 6 6 6 0 6 6 6 4 6 6 4 4 6 6 4 316 4 h 4 6 4 6 4 6 6 4666660666464644 6 H 10 4 4 4 4 6 4 64 6 4 4 6 6 6 0 6 6 6 6 4 6 4 6 4 H2, 4 4 4 4 6 6 4 6 4 4 4 6 4 6 6 6 0 6 6 6 4 4 6 4 6 H3 4 4 10 4 6 4 4 6 6 4 4 4 6 6 4 6 6 6 0 6 4 6 6 4 4 6 H4 4 4 4 10 6 4 6 4 4 6 4 4 6 6 6 4 6 6 6 0 4 6 4 6 6 4 H5 4 4 6 6 10 6 4 4 4 4 4 6 4 4 6 6 6 6 4 4 0 4 6 6 6 6 H6 6 6 446 0444 4 4 6 6 6 4 4 4 4 6 6 4 0 6 6 6 H7 4 4 6 4 4 10 6 4 4 6 4 6 4 6 6 4 6 4 6 6 0 4 6 6 H8 6 6 444 6 10 4 4 4 6 6 4 6 4 4 6 4 6 6 6 4 0 6 6 aH9 4 6 6 4 4 4 4 4 10 6 4 6 4 6 6 4 6 4 4 6 6 6 6 0 4 -I16 64T44io1 44 6 46 6 6604 A value in Table 1-3 represents a code distance between two codewords. 10 Furthermore, the mapping the feedback signals of the three carriers into the codeword may comprise: mapping a feedback signal DTX-NACK-DTX into G8; mapping a feedback signal DTX-ACK-DTX into H8; mapping a feedback signal NACK-DTX-DTX into H3; mapping a feedback signal NACK-NACK-DTX into H7; mapping a feedback signal NACK-ACK-DTX into 15 H9; mapping a feedback signal ACK-DTX-DTX into G3; mapping a feedback signal ACK-NACK-DTX into G4; mapping a feedback signal ACK-ACK-DTX into H6; 3 mapping a feedback signal DTX-DTX-NACK into Hi; mapping a feedback signal DTX-NACK-NACK into G6; mapping a feedback signal DTX-ACK-NACK into G10; mapping a feedback signal NACK-DTX-NACK into G2; mapping a feedback signal NACK-NACK-NACK into H2; mapping a feedback signal NACK-ACK-NACK into G16; mapping a feedback signal 5 ACK-DTX-NACK into G12; mapping a feedback signal ACK-NACK-NACK into G15; mapping a feedback signal ACK-ACK-NACK into G5; and mapping a feedback signal DTX-DTX-ACK into Gi; mapping a feedback signal DTX-NACK-ACK into G14; mapping a feedback signal DTX-ACK-ACK into G7; mapping a feedback signal NACK-DTX-ACK into H4; mapping a feedback signal NACK-NACK-ACK into 0 H5; mapping a feedback signal NACK-ACK-ACK into Gl; mapping a feedback signal ACK-DTX-ACK into H10; mapping a feedback signal ACK-NACK-ACK into G9; and mapping a feedback signal ACK-ACK-ACK into G13. Furthermore, a mapping relationship between the codeword and the bit sequence is as shown in Table 1-3.1: 5 Table 1-3.1 Codeword Bit sequence GI 1 0 0 0 1 0 1 0 1 0 G2 0 0 1 1 1 0 0 0 0 1 G3 1 1 1 1 1 1 1 1 1 1 G4 1 0 1 0 0 1 0 1 0 0 G5 1 1 1 1 0 0 0 1 1 0 G6 1 1 1 0 0 1 1 0 0 1 G7 0 0 1 0 0 1 0 0 1 1 G8 0 0 1 1 0 0 1 1 0 0 G9 0 1 1 0 1 0 1 1 0 1 G1O 0 1 1 1 1 1 0 0 1 0 Gil 0 1 0 1 0 1 1 0 0 0 G12 0 1 0 0 0 0 0 1 1 1 G13 1 0 0 1 1 1 0 1 0 1 G14 0 0 1 0 1 1 1 1 1 0 G15 1 1 1 0 1 0 0 0 0 0 G16 1 0 1 1 0 0 1 0 1 1 HI 0 1 1 1 0 1 0 1 0 1 H2 1 1 0 0 0 1 1 1 1 0 H3 0 0 0 0 0 0 0 0 0 0 H4 0 1 0 1 1 0 1 0 1 1 H5 0 0 0 0 1 1 1 0 0 1 H6 0 0 0 1 1 0 0 1 1 0 H7 1 1 0 1 1 0 1 1 0 0 H8 1 1 0 0 1 1 0 0 1 1 H9 1 0 0 1 0 1 0 0 1 0 HIO 1 0 0 0 0 0 1 1 0 1 According to another aspect of the present invention, a method for encoding feedback signals is provided. The method may include: encoding feedback signals of three carriers to output a bit sequence; and 4 transmitting the bit sequence on an uplink HS-DPCCH, in which the encoding the feedback signals of the three carriers includes: mapping the feedback signals of the three carriers into a codeword selected from a codebook, in which the codebook comprises codewords Al to A6, B1 to B6, C1 to C6, and D1 to D6, in which code distance relationships of the 5 codewords in the codebook are as shown in Table 1-4: Table 1-4 Al A2 A3 A4 A5 A6 BI B2 B3 B4 B5 B6 C1 C2 C3 C4 C5 C6 D1 D2 D3 D4 D5 D6 A1 0 6 6 6 6 6 10 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A2 6 0 6 6 6 6 4 10 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A3 6 6 0 6 6 6 4 4 10 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A4 6 6 60 6 4 4 4 10 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A5 6 6 6 6 0 6 4 4 4 4 10 4 5 5 5 5 5 5 5 5 5 5 5 5 A6 6 6 6 6 6 0 4 4 4 4 4 10 5 5 5 5 5 5 5 5 5 5 5 5 B1 10 4 4 4 4 4 0 6 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B2 4 10 4 4 4 4 6 0 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B3 4 4 10 4 4 4 6 6 0 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B4 4 4 4 10 4 4 6 6 6 0 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B5 4 4 4 4 10 4 6 6 6 6 0 6 5 5 5 5 5 5 5 5 5 5 5 5 B6 4 4 4 4 4 10 6 6 6 6 6 0 5 5 5 5 5 5 5 5 5 5 5 5 CI 5 5 5 5 5 5 5 5 5 5 5 0 6 6 6 6 6 10 4 4 4 4 4 C2 5 5 5 5 5 5 5 5 5 5 5 5 6 0 6 6 6 6 4 10 4 4 4 4 C3 5 5 5 5 5 5 5 5 5 5 5 5 6 6 0 6 6 6 4 4 10 4 4 4 C4 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 0 6 6 4 4 4 10 4 4 C5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 0 6 4 4 4 4 10 4 C6 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 0 4 4 4 4 4 10 D1 5 5 5 5 5 5 5 5 5 5 5 5 10 4 4 4 4 4 0 6 6 6 6 6 D2 5 5 5 5 5 5 5 5 5 5 5 5 4 10 4 4 4 4 6 0 6 6 6 6 D3 5 5 5 5 5 5 5 5 5 5 5 5 4 4 10 4 4 4 6 6 0 6 6 6 D4 5 5 5 5 5 5 5 5 5 5 5 5 4 4 4 10 4 4 6 6 6 0 6 6 D5 5 5 5 5 5 5 5 5 5 5 5 5 4 4 4 4 10 4 6 6 6 6 0 6 D6 5 5 55 5 5 5 5 5 5 5 4 4 4 4 4 10 66 6 6 6 0 where a value in Table 1-4 represents a code distance between corresponding codewords. Furthermore, the mapping the feedback signals of the three carriers into the codeword may comprise: 10 mapping a feedback signal DTX-NACK-DTX into Dl; mapping a feedback signal DTX-ACK-DTX into Cl; mapping a feedback signal NACK-DTX-DTX into B1; mapping a feedback signal NACK-NACK-DTX into C2; mapping a feedback signal NACK-ACK-DTX into A2; mapping a feedback signal ACK-DTX-DTX into Al; mapping a feedback signal ACK-NACK-DTX into B2; mapping a feedback signal ACK-ACK-DTX into D2; 15 mapping a feedback signal DTX-DTX-NACK into A3; mapping a feedback signal DTX-NACK-NACK into C2; mapping a feedback signal DTX-ACK-NACK into C5; mapping a feedback signal NACK-DTX-NACK into D6; mapping a feedback signal NACK-NACK-NACK into C2; mapping a feedback signal NACK-ACK-NACK into A5; mapping a feedback signal 5 ACK-DTX-NACK into D4; mapping a feedback signal ACK-NACK-NACK into A4; mapping a feedback signal ACK-ACK-NACK into B6; and mapping a feedback signal DTX-DTX-ACK into B3; mapping a feedback signal DTX-NACK-ACK into C3; mapping a feedback signal DTX-ACK-ACK into C4; mapping a 5 feedback signal NACK-DTX-ACK into D5; mapping a feedback signal NACK-NACK-ACK into A6; mapping a feedback signal NACK-ACK-ACK into B4; mapping a feedback signal ACK-DTX-ACK into D3; mapping a feedback signal ACK-NACK-ACK into B5; and mapping a feedback signal ACK-ACK-ACK into C6. Alternatively, the mapping the feedback signals of the three carriers into the codeword may 0 comprise: mapping a feedback signal DTX-NACK-DTX into Dl; mapping a feedback signal DTX-ACK-DTX into Cl; mapping a feedback signal NACK-DTX-DTX into B1; mapping a feedback signal NACK-NACK-DTX into C2; mapping a feedback signal NACK-ACK-DTX into A2; mapping a feedback signal ACK-DTX-DTX into Al; mapping a feedback signal 5 ACK-NACK-DTX into B2; mapping a feedback signal ACK-ACK-DTX into D2; mapping a feedback signal DTX-DTX-NACK into A3; mapping a feedback signal DTX-NACK-NACK into C5; mapping a feedback signal DTX-ACK-NACK into C4; mapping a feedback signal NACK-DTX-NACK into C2; mapping a feedback signal NACK-NACK-NACK into C2; mapping a feedback signal NACK-ACK-NACK into A5; mapping a feedback signal 0 ACK-DTX-NACK into D3; mapping a feedback signal ACK-NACK-NACK into A4; mapping a feedback signal ACK-ACK-NACK into B6; and mapping a feedback signal DTX-DTX-ACK into B3; mapping a feedback signal DTX-NACK-ACK into B4; mapping a feedback signal DTX-ACK-ACK into D5; mapping a feedback signal NACK-DTX-ACK into C3; mapping a feedback signal NACK-NACK-ACK into 25 D4; mapping a feedback signal NACK-ACK-ACK into D6; mapping a feedback signal ACK-DTX-ACK into B5; mapping a feedback signal ACK-NACK-ACK into A6; and mapping a feedback signal ACK-ACK-ACK into C6. Alternatively, the mapping the feedback signals of the three carriers into the codeword may comprise: 30 mapping a feedback signal DTX-NACK-DTX into Dl; mapping a feedback signal DTX-ACK-DTX into Cl; mapping a feedback signal NACK-DTX-DTX into B1; mapping a feedback signal NACK-NACK-DTX into C2; mapping a feedback signal NACK-ACK-DTX into C5; mapping a feedback signal ACK-DTX-DTX into Al; mapping a feedback signal ACK-NACK-DTX into A4; mapping a feedback signal ACK-ACK-DTX into D3; 6 mapping a feedback signal DTX-DTX-NACK into A3; mapping a feedback signal DTX-NACK-NACK into A2; mapping a feedback signal DTX-ACK-NACK into C4; mapping a feedback signal NACK-DTX-NACK into C2; mapping a feedback signal NACK-NACK-NACK into C2; mapping a feedback signal NACK-ACK-NACK into A5; mapping a feedback signal 5 ACK-DTX-NACK into D3; mapping a feedback signal ACK-NACK-NACK into B2; mapping a feedback signal ACK-ACK-NACK into B6; and mapping a feedback signal DTX-DTX-ACK into B3; mapping a feedback signal DTX-NACK-ACK into B4; mapping a feedback signal DTX-ACK-ACK into D4; mapping a feedback signal NACK-DTX-ACK into D4; mapping a feedback signal NACK-NACK-ACK into 0 C3; mapping a feedback signal NACK-ACK-ACK into D6; mapping a feedback signal ACK-DTX-ACK into B5; mapping a feedback signal ACK-NACK-ACK into A6; and mapping a feedback signal ACK-ACK-ACK into C6. Furthermore, a mapping relationship between the codeword and the bit sequence is as shown in Table 1-4.1: 5 Table 1-4.1 Codeword Bit sequence Al 1 1 1 1 1 1 1 1 1 1 A2 0 0 1 1 0 0 1 1 0 0 A3 1 1 0 0 0 1 1 0 0 0 A4 1 0 0 1 0 0 0 0 1 1 A5 0 1 0 0 1 0 0 1 1 0 A6 0 0 1 0 1 1 0 0 0 1 BI 0 0 0 0 0 0 0 0 0 0 B2 1 1 0 0 1 1 0 0 1 1 B3 0 0 1 1 1 0 0 1 1 1 B4 0 1 1 0 1 1 1 1 0 0 B5 1 0 1 1 0 1 1 0 0 1 B6 1 1 0 1 0 0 1 1 1 0 C1 1 1 1 1 1 0 0 0 0 0 C2 0 1 0 1 0 1 0 1 0 1 C3 0 1 1 0 0 0 1 0 1 1 C4 1 0 1 0 0 1 0 1 1 0 C5 0 0 0 1 1 1 1 0 1 0 C6 1 0 0 0 1 0 1 1 0 1 D1 0 0 0 0 0 1 1 1 1 1 D2 1 0 1 0 1 0 1 0 1 0 D3 1 0 0 1 1 1 0 1 0 0 D4 0 1 0 1 1 0 1 0 0 1 D5 1 1 1 0 0 0 0 1 0 1 D6 0 1 1 1 0 1 0 0 1 0 According to further another aspect of the present invention, a method for encoding feedback signals is provided. The method may include: encoding feedback signals of three carriers; and transmitting a bit sequence encoded and output on an uplink HS-DPCCH, in which 7 the encoding the feedback signals of the three carriers includes: mapping the feedback signals of the three carriers into a codeword selected from a codebook, in which the codebook comprises codewords Al to A6, B1 to B6, C1 to C6, D1 to D6, El, and Fl, in which code distance relationships of the codewords in the codebook are as shown in Table 1-5: 5 Table 1-5 Al A2 A3 A4 A5 A6 BI B2 B3 B4 B5 B6 Cl C2 C3 C4 C5 C6 D1 D2 D3 D4 D5 D6 El F1 A1 0 6 6 6 6 610 4 4 4 45 5 5 5 5 5555564 A2 6 0 6 6 66 4 10 4 4 5 5 5 5 5 5 5 5 5 5 5 6 4 A3 6 6 0 6 66 4 4 104 4 5 5 5 5 5 5 5 5 5 5 5 6 4 A4 6 6 6 0 6 6 4 4 4 10 4 4 5 5 5 5 5 5 5 5 5 5 5 5 4 6 A5 6 6 6 6 0 6 4 4 4 10 4 5 5 5 5 5 5 5 5 5 5 5 4 6 A6 6 6 66 6 0 4 4 4 4 4 10 5 5 5 5 5 5 5 5 5 5 5 5 4 6 B 10 4 4 4 4 4 0 6 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 4 6 B2 4 10 4 4 44 6 0 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 4 6 B34 4 10 4 4 4 6 6 0 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 4 6 B4 4 4 4 10 4 6 6 6 0 6 6 5 5 5 5 5 5 5 5 5 5 5 5 6 4 B5 4 4 4 10 4 6 6 6 6 0 6 5 5 5 5 5 5 5 5 5 5 5 6 4 B6 4 4 44 4 10 6 6 6 6 6 0 5 5 5 5 5 5 5 5 51515 5 6 4 C 5 5 5 5 5 5 5 55 5 0 6 6 6 6 6 10 4 4 4 4 4 7 3 C2 5 5 5 5 5 5 5 5 5 5 5 6 0 6 6 6 6 4 10 4 4 4 4 7 3 C3 5 5 5 5 5 5 5 55 5 6 6 0 6 6 6 4 410 4 4 4 3 7 C4 5 5 5 5 5 5 5 5 5 5 5 6 6 6 0 6 6 4 4 4 10 4 4 7 3 C 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 0 6 4 4 44,10 4 3 7 C6 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 0 4 4 4 4 4 10 3 7 Dl 5 5 5 5 5 5 5 5 5 5 5 10 4 4 4 4 4 0 6 6 6 6 6 3 7 D2 5 5 5 5 5 5 5 5 5 5 5 4 10 4 4 4 4 6 0 6 6 6 6 3 7 D3 5 5 5 5 5 5 5 5 5 5 5 4 4 10 4 4 4 6 6 0 6 6 6 7 3 D4 5 5 5 5 515 5 5 5 5 5 5 4 4 4 10 4 4 6 6 6 0 6 6 3 7 D55 5 5 5 5 1 5 5 5 5 5 5 4 4 4 4 104 6 6 6 0 6 7 3 D6 5 5 5 5 5 5 5 5 5 5 5 4 4 4 4 410 6 6 6 6 0 7 3 E 6 6 4 4 4 4 4 4 6 6 6 7 7 3 7 3 3 3 3 7 3 7 7 0 10 F1 4 4 4 6 6 1 6 6 6 6 4 4 3 3 7, 3 7 7 7 7 3 7 3 3 10, 0 where a value in Table 1-5 represents a code distance between two codewords. Furthermore, the mapping the feedback signals of the three carriers into the codeword may comprise: mapping a feedback signal DTX-NACK-DTX into Dl; mapping a feedback signal 10 DTX-ACK-DTX into Cl; mapping a feedback signal NACK-DTX-DTX into B1; mapping a feedback signal NACK-NACK-DTX into C2; mapping a feedback signal NACK-ACK-DTX into A2; mapping a feedback signal ACK-DTX-DTX into Al; mapping a feedback signal ACK-NACK-DTX into B2; mapping a feedback signal ACK-ACK-DTX into D2; mapping a feedback signal DTX-DTX-NACK into B3; mapping a feedback signal 15 DTX-NACK-NACK into El; mapping a feedback signal DTX-ACK-NACK into C6; mapping a feedback signal NACK-DTX-NACK into D3; mapping a feedback signal NACK-NACK-NACK into Fl; mapping a feedback signal NACK-ACK-NACK into A5; mapping a feedback signal 8 ACK-DTX-NACK into D6; mapping a feedback signal ACK-NACK-NACK into A6; mapping a feedback signal ACK-ACK-NACK into B4; and mapping a feedback signal DTX-DTX-ACK into A3; mapping a feedback signal DTX-NACK-ACK into C3; mapping a feedback signal DTX-ACK-ACK into D5; mapping a 5 feedback signal NACK-DTX-ACK into C4; mapping a feedback signal NACK-NACK-ACK into C5; mapping a feedback signal NACK-ACK-ACK into D4; mapping a feedback signal ACK-DTX-ACK into B5; mapping a feedback signal ACK-NACK-ACK into A4; and mapping a feedback signal ACK-ACK-ACK into B6. Alternatively, the mapping the feedback signals of the three carriers into the codeword may 0 comprise: mapping a feedback signal DTX-NACK-DTX into A2; mapping a feedback signal DTX-ACK-DTX into B2; mapping a feedback signal NACK-DTX-DTX into B 1; mapping a feedback signal NACK-NACK-DTX into El; mapping a feedback signal NACK-ACK-DTX into D2; mapping a feedback signal ACK-DTX-DTX into Al; mapping a feedback signal 5 ACK-NACK-DTX into C5; mapping a feedback signal ACK-ACK-DTX into B4; mapping a feedback signal DTX-DTX-NACK into A3; mapping a feedback signal DTX-NACK-NACK into Fl; mapping a feedback signal DTX-ACK-NACK into Cl; mapping a feedback signal NACK-DTX-NACK into C2; mapping a feedback signal NACK-NACK-NACK into C6; mapping a feedback signal NACK-ACK-NACK into D5; mapping a feedback signal 0 ACK-DTX-NACK into C4; mapping a feedback signal ACK-NACK-NACK into A6; mapping a feedback signal ACK-ACK-NACK into D3; and mapping a feedback signal DTX-DTX-ACK into B3; mapping a feedback signal DTX-NACK-ACK into C3; mapping a feedback signal DTX-ACK-ACK into B6; mapping a feedback signal NACK-DTX-ACK into B5; mapping a feedback signal NACK-NACK-ACK into 25 D4; mapping a feedback signal NACK-ACK-ACK into A4; mapping a feedback signal ACK-DTX-ACK into D6; mapping a feedback signal ACK-NACK-ACK into Dl; and mapping a feedback signal ACK-ACK-ACK into A5. Furthermore, a mapping relationship between the codeword and the bit sequence is as shown in Table 1-5.1: 30 Table 1-5.1 Codeword Bit sequence Al 1 1 1 1 1 1 1 1 1 1 A2 0 0 1 1 0 0 1 1 0 0 A3 1 1 0 0 0 1 1 0 0 0 A4 1 0 0 1 0 0 0 0 1 1 A5 0 1 0 0 1 0 0 1 1 0 A6 0 0 1 0 1 1 0 0 0 1 9 BI 0 0 0 0 0 0 0 0 0 0 B2 1 1 0 0 1 1 0 0 1 1 B3 0 0 1 1 1 0 0 1 1 1 B4 0 1 1 0 1 1 1 1 0 0 B5 1 0 1 1 0 1 1 0 0 1 B6 1 1 0 1 0 0 1 1 1 0 C1 1 1 1 1 1 0 0 0 0 0 C2 0 1 0 1 0 1 0 1 0 1 C3 0 1 1 0 0 0 1 0 1 1 C4 1 0 1 0 0 1 0 1 1 0 C5 0 0 0 1 1 1 1 0 1 0 C6 1 0 0 0 1 0 1 1 0 1 D1 0 0 0 0 0 1 1 1 1 1 D2 1 0 1 0 1 0 1 0 1 0 D3 1 0 0 1 1 1 0 1 0 0 D4 0 1 0 1 1 0 1 0 0 1 D5 1 1 1 0 0 0 0 1 0 1 D6 0 1 1 1 0 1 0 0 1 0 El 0 0 0 0 1 0 1 0 1 1 F1 1 1 1 1 0 1 0 1 0 0 According to still further another aspect of the present invention, a method for encoding feedback signals is provided. The method may include: encoding feedback signals of three carriers to output a bit sequence; and transmitting the bit sequence on an uplink HS-DPCCH, in which 5 the encoding the feedback signals of the three carriers includes: mapping the feedback signals of the three carriers into a codeword selected from a codebook, in which the codebook comprises codewords Al to A6, B1 to B6, C1 to C6, D1 to D6, El, and Fl, in which code distance relationships of the codewords in the codebook are as shown in Table 1-6: Table 1-6 AlA2A3 A4A5A6B1B2B3B4 5 B6C1 C2C3 C4C5C6D1 2D3D4D5D6E2F2 A10 6 6 6 6 6 104 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 3 A26 0 6 6 6 6 4 10 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 A36 6 6 6 6 4 10 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 A46 6 6 0 6 6 4 4 10 4 5 5 5 5 5 5 5 5 5 5 5 5 3 7 A56 6 6 6 6 4 4 10 4 5 5 5 5 5 5 5 5 5 5 5 5 3 A66 6 6 6 6 0 4 4 10 5 5 5 5 5 5 5 5 5 5 5 5 3 7 B110 4 4 4 6 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 3 7 B24 10 4 4 6 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 5 5 B34 4 10 4 4 6 6 0 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 5 5 B44 4 10 4 6 6 6 0 6 6 5 5 5 5 5 5 5 5 5 5 5 5 3 B54 4 4 10 4 6 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 3 7 B64 4 4 10 6 6 6 6 6 0 5 5 5 5 5 5 5 5 5 5 5 5 3 C15 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 10 4 4 6 4 C2 5 5 5 5 5 5 5 5 5 5 5 5 6 0 6 6 6 6 4 10 4 4 8 C3 5 5 5 5 5 5 5 5 5 5 5 5 6 6 0.6 6 6 4 10 4 4 6 4 C45 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 4 10 4 6 4 10 C55 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 4 4 10 6 C65 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 0 4 4 4 10 6 4 D15 5 5 5 5 5 5 5 5 5 5 5 104 4 4 4 0 6 6 6 6 6 6 D25 5 5 5 5 5 5 5 5 5 5 5 10 4 4 6 6 6 6 6 8 2 D35 5 5 5 5 5 5 5 5 5 5 5 4 10 4 4 6 6 6 6 6 D45 5 5 5 5 5 5 5 5 5 5 5 4 4 10 4 4 6 6 6 0 6 6 6 D55 5 5 5 5 5 5 5 5 5 5 5 4 4 10 4 6 6 6 6 0 6 6 4 D65 5 5 5 5 5 5 5 5 5 5 5 4 4 106 6 6 6 6 6 E27 5 5 3 3 3 5 5 7 3 7 6 2 6 6 6 4 8 4 6 10 F2 3 5 5 7 3 7 5 5 3 3 8 4 6 4 6 6 6 4 6 10 0 where a value in Table 1-6 represents a code distance between two codewords. Furthermore, the mapping the feedback signals of the three carriers into the codeword may comprise: mapping a feedback signal DTX-NACK-DTX into Dl; mapping a feedback signal 5 DTX-ACK-DTX into Cl; mapping a feedback signal NACK-DTX-DTX into B1; mapping a feedback signal NACK-NACK-DTX into C2; mapping a feedback signal NACK-ACK-DTX into A2; mapping a feedback signal ACK-DTX-DTX into Al; mapping a feedback signal ACK-NACK-DTX into B2; mapping a feedback signal ACK-ACK-DTX into D2; mapping a feedback signal DTX-DTX-NACK into B6; mapping a feedback signal 0 DTX-NACK-NACK into C5; mapping a feedback signal DTX-ACK-NACK into C6; mapping a feedback signal NACK-DTX-NACK into D4; mapping a feedback signal NACK-NACK-NACK into E2; mapping a feedback signal NACK-ACK-NACK into A3; mapping a feedback signal ACK-DTX-NACK into D3; mapping a feedback signal ACK-NACK-NACK into A5; mapping a feedback signal ACK-ACK-NACK into F2; and 5 mapping a feedback signal DTX-DTX-ACK into A6; mapping a feedback signal DTX-NACK-ACK into C4; mapping a feedback signal DTX-ACK-ACK into C3; mapping a feedback signal NACK-DTX-ACK into D5; mapping a feedback signal NACK-NACK-ACK into A4; mapping a feedback signal NACK-ACK-ACK into B5; mapping a feedback signal ACK-DTX-ACK into D6; mapping a feedback signal ACK-NACK-ACK into B3; and mapping a 20 feedback signal ACK-ACK-ACK into B4. Furthermore, a mapping relationship between the codeword and the bit sequence is as shown in Table 1-6.1: Table 1-6.1 Codeword Bit sequence Al 1 1 1 1 1 1 1 1 1 A2 0 0 1 1 0 0 1 1 0 0 A3 1 1 0 0 0 1 1 0 0 0 A4 1 0 0 1 0 0 0 0 1 1 A5 0 1 0 0 1 0 0 1 1 0 11 A6 0 0 1 0 1 1 0 0 0 1 BI 0 0 0 0 0 0 0 0 0 0 B2 1 1 0 0 1 1 0 0 1 1 B3 0 0 1 1 1 0 0 1 1 1 B4 0 1 1 0 1 1 1 1 0 0 B5 1 0 1 1 0 1 1 0 0 1 B6 1 1 0 1 0 0 1 1 1 0 C1 1 1 1 1 1 0 0 0 0 0 C2 0 1 0 1 0 1 0 1 0 1 C3 0 1 1 0 0 0 1 0 1 1 C4 1 0 1 0 0 1 0 1 1 0 C5 0 0 0 1 1 1 1 0 1 0 C6 1 0 0 0 1 0 1 1 0 1 D1 0 0 0 0 0 1 1 1 1 1 D2 1 0 1 0 1 0 1 0 1 0 D3 1 0 0 1 1 1 0 1 0 0 D4 0 1 0 1 1 0 1 0 0 1 D5 1 1 1 0 0 0 0 1 0 1 D6 0 1 1 1 0 1 0 0 1 0 E2 0 0 0 1 0 1 0 0 0 1 F2 1 1 1 0 1 0 1 1 1 0 According to still further another aspect of the present invention, an apparatus for encoding feedback signal is provided. The apparatus may include: an encoder, configured to encode feedback signals of three carriers to output a bit sequence; and 5 a transmitter, configured to transmit the bit sequence encoded on an uplink HS-DPCCH, in which the encoder is further configured to map the feedback signals of the three carriers into a codewords selected from a codebook, in which the codebook comprises codewords G1 to G16 and H1 to H10, and code distance relationships of the codewords in the codebook are as shown in Table 10 1-3. According to still further another aspect of the present invention, an apparatus for encoding feedback signal is provided. The apparatus may include: an encoder, configured to encode feedback signals of three carriers to output a bit sequence; a transmitter, configured to transmit the bit sequence on an uplink HS-DPCCH, in which 15 the encoder is further configured to map the feedback signals of the three carriers into a codeword selected from a codebook, in which the codebook comprises codewords Al to A6, B 1 to B6, C1 to C6, and D1 to D6, and code distance relationships of the codewords in the codebook are as shown in Table 1-4. According to still further another aspect of the present invention, an apparatus for encoding 20 feedback signals is provided. The apparatus may include: an encoder, configured to encode feedback signals of three carriers to output a bit sequence; 12 and a transmitter, configured to transmit the bit sequence on an uplink HS-DPCCH, in which the encoder is further configured to map the feedback signals of the three carriers into a codeword selected from a codebook, in which the codebook comprises codewords Al to A6, B 1 to 5 B6, C1 to C6, D1 to D6, El, and Fl, and code distance relationships of the codewords in the codebook are as shown in Table 1-5. According to still further another aspect of the present invention, an apparatus for encoding feedback signals is provided. The apparatus may include: an encoder, configured to encode feedback signals of three carriers to output a bit sequence; 0 and a transmitter, configured to transmit the bit sequence on an uplink HS-DPCCH, in which the encoder is further configured to map the feedback signals of the three carriers into a codeword selected from a codebook, in which the codebook comprises codewords Al to A6, B 1 to B6, C1 to C6, D1 to D6, El, and Fl, in which code distance relationships of the codewords in the 5 codebook are as shown in Table 1-6. The present invention provides methods for jointly encoding feedback signals of three carriers in TC mode. In the embodiments of the present invention, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. BRIEF DESCRIPTION OF THE DRAWINGS 0 FIG. 1 is a schematic structure of a HARQ-ACK joint encoder in TC mode according to an embodiment of the present invention; FIG. 2 is a flow chart of a method for encoding feedback signals according to another embodiment of the present invention; and FIG. 3 is a schematic structure of an apparatus for encoding feedback signals according to 25 further another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a schematic structure of a HARQ-ACK joint encoder in TC mode according to an embodiment of the present invention. In TC mode, a Node B transmits data to a UE on at most three carriers simultaneously, and after receiving at most three data blocks, the UE is required to transmit 30 feedback for receiving the data each, in which feedback information includes DTX, ACK, and NACK. The UE synthesizes the feedback information of the three carriers, namely, encodes the 13 feedback information into a 10-bit 0-1 sequence, and transmit to the Node B through a HS-DPCCH. The Node B selects a decode space to decode the feedback information according to the sending mode. As shown in FIG. 1, the input signals of the joint encoder are feedback signals for a UE 5 receiving data, i, j, and k are feedback signals for receiving data from three carriers. Values of i, j, and k may be DTX, ACK, or NACK. The output signal of the joint encoder is a 10-bit 0-1 sequence, represented with Xijk. Functions of the joint encoder are that the UE encodes feedback signals of at most three carriers, and transmits the outputted bit sequence on a HS-DPCCH. When the Node B applies three carriers to send data, seven data sending modes exist with 0 reference to Table 1-7. Table 1-7 Data Sending Mode With TC Carrier 1 Carrier 2 Carrier 3 Mode 1 On Off Off Mode 2 Off On Off Mode 3 Off Off On Mode 4 On On Off Mode 5 On Off On Mode 6 Off On On Mode 7 On On On In Table 1-7, "On" indicates that data is sent on the carrier, and "Off" indicates that data is not sent on the carrier or the carrier is deactivated. Each of the sending modes corresponds to a decoding space, with reference to Table 1-8. After 5 receiving the encoded feedback signals of the UE, the Node B may select a decoding space according to a sending mode, and decode the feedback signals in the decoding space. Table 1-8 Relationship Between Sending Modes And Decoding Spaces Sending Decoding Space Mode Mode 1 DTX, N-D-D, A-D-D Mode 2 DTX, D-N-D, D-A-D Mode 3 DTX, D-D-N, D-D-A Mode 4 DTX, D-N-D, D-A-D, N-D-D, A-D-D, N-N-D, A-N-D, N-A-D, A-A-D Mode 5 DTX, N-D-D, A-D-D, D-D-N, D-D-A, N-D-N, N-D-A, A-D-N, A-D-A Mode 6 DTX, D-N-D, D-A-D, D-D-N, D-D-A, D-N-N, D-N-A, D-A-N, D-A-A DTX, D-N-D, D-A-D, N-D-D, A-D-D, N-N-D, A-N-D, N-A-D, A-A-D, D-D-N, D-D-A, Mode 7 N-D-N, N-D-A, A-D-N, A-D-A, D-N-N, D-N-A, D-A-N, D-A-A, N-N-N, N-N-A, N-A-N, N-A-A, A-N-N, A-N-A, A-A-N, A-A-A In Table 1-8, for example, a feedback signal N-D-A is an abbreviation of NACK-DTX-ACK, which indicates that feedback information of Carrier 1 is NACK, feedback information of Carrier 2 14 is DTX, and feedback information of Carrier 3 is ACK. Other feedback signals are similar to this. Embodiment 1 of a method for encoding feedback signals FIG. 2 is a flow chart of a method for encoding feedback signals according to an embodiment of the present invention. As shown in FIG. 2, the method includes the following steps: 5 Step 101: encode feedback signals of three carriers to output a bit sequence. Step 102: transmit the bit sequence on a HS-DPCCH. The Step 101 may specifically include mapping the feedback signals of the three carriers into a codeword selected from a codebook. The codebook satisfies a particular code distance relationship, which may be acquired through computer searching or by using other methods. Under a condition 0 that a certain requirement (such as compatibility) is satisfied, a principle of selecting a codebook is that the smallest code distance is maximized, and the number of the smallest code distances is minimized. The codebook of this embodiment includes 26 codewords in total, and these codewords are selected from the codebook comprising codewords G1 to G16 and H1 to H10. For code distance 5 relationships between codewords, reference can be made to Table 1-9. Table 1-9 Code Distance Relationships Between Codewords GI G2 G3 G4 G5 G6 G7 G8 G9 G1O G11 G12 Gi3 G14 G5 GI6 HI H2 H3 H4 H5 H6 H7 H8 H9 HI GI 0 6 6 6 6 4 6 4 6 4 6 6 6 4 4 4 10 4 4 4 6 4 6 4 6 G2 6 0 6 6 64 6 4 6 6 6 4 6 4 4 4 10 4 4 46 6 46 4 G3 6 6 0 6 4 6 6 4 4 4 10 4 6 4 4 6 6 4 G4 6 6 6 0 4 6 4 6 6 4 6 6 4 4 6 4 4 4 0 6 4 6 4 4 6 G5 6 6 5 4 0 4 6 6 6 6 6 4 6 6 4 4 4 6 10 6 4 4 4 4 G6 4 4 6 4 0 6 6 6 6 6 4 4 4 6 6 6 4 4 6 10 4 4 4 G7 6 4 6 4 6 6 4 6 6 6 4 6 4 6 4 4 6 4 6 4 4 10 6 4 4 G8 4 6 6 6 6 4 0 6 6 6 4 4 6 4 6 6 4 6 4 4 4 6 0 44 G9 6 4 6 6 6 6 6 0 4 6 4 6 4 4 6 4 6 6 4 4 4 4 10 6 G1 4 6 64 6 6 6 6 4 0 6 4 4 6 6 4 6 4 4 6 4 4 4 6 10 G11 6 6 6 6 6 6 66 6 0 6 6 6 6 44444444 G12 6 6 6 4 4 4 4 4 4 6 0 6 6 6 6 4 4 4 4 6 6 6 6 6 6 3 6 4 4 4 6 4 6 4 6 4 6 6 0 6 6 6 4 6 6 6 4 6 4 6 4 6 14 4 6 4 4 6 4 4 6 4 6 6 6 6 0 6 6 6 4 6 6 4 6 6 4 64 G15 4 4 6 4 4 6 6 4 4 6 6 6 6 6 0 6 6 6 4 6 6 4 4 6 6 4 316 4 4 h 6 4 6 4 6 6 466 6 0 6 66 646 4 6 H 10 4 4 4 46 4 6 4 6 4 4 4 6 6 6 0 6 6 6 6 4 6 4 6 4 H2 4 10 4 4 46 6 4 6 4 4 4 6 4 6 6 6 0 6 6 6 4 4 6 4 6 H3 4 4 1 4 6 4 4 6 6 4 4 4 6 6 4 6 6 6 0 6 4 6 6 4 4 6 H4 4 4 7 10 6 4 6 4 4 6 4 4 6 6 6 4 6 6 6 0 4 6 4 6 6 4 H5 4 4 6 10 6 4 4 4 4 4 6 4 4 6 6 6 6 4 4 0 4 6 6 66 H6 6 6 4 6 10 4 4 4 4 4 6 6 6 4 4 4 4 6 6 4 0 6 6 66 H7 4 6 6 4 4io 6 4 4 4 6 4 6 4 6 6 4 6 4 6 6 0 4 6 6 H8 6 4 6 4 4 4 6 10 4 4 4 6 6 4 6 4 4 6 4 6 6 6 4 0 6 6 15 I 914 61 14 41 14 41116 14 16 14 16 16 14 1 61414 16 16 16 16 16 101 4 H106 446 4 414 1416110 14 16 1614 141614 161614 1616 161614 10 A value in Table 1-9 represents a code distance between two codewords, for example, the code distance between G1 and G2 is 6, the code distance between G1 and G6 is 4, and so on. Further, in step 101, for mapping the feedback signals into a codeword selected from the codebook, reference can be made to Table 1-10. 5 Table 1-10 Mapping Solution Between Feedback Signals And Codewords Feedback Feedback Feedback signal of Carrier 2 signal of signal of DXNC C Carrier 3 Carrier 1 DTX NACK ACK DTX * G8 H8 DTX NACK H3 H7 H9 ACK G3 G4 H6 DTX HI G6 G1O NACK NACK G2 H2 G16 ACK G12 G15 G5 DTX GI G14 G7 ACK NACK H4 H5 G11 ACK HIO G9 G13 It can be seen from Table 1-10 that, in this embodiment, the feedback signal D-N-D is mapped into G8; the feedback signal D-A-D is mapped into H8; the feedback signal N-D-D is mapped into H3; the feedback signal N-N-D is mapped into H7; the feedback signal N-A-D is mapped into H9; the feedback signal A-D-D is mapped into G3; the feedback signal A-N-D is mapped into G4; the 10 feedback signal A-A-D is mapped into H6; the feedback signal D-D-N is mapped into Hi; the feedback signal D-N-N is mapped into G6; the feedback signal D-A-N is mapped into G10; the feedback signal N-D-N is mapped into G2; the feedback signal N-N-N is mapped into H2; the feedback signal N-A-N is mapped into G16; the feedback signal A-D-N is mapped into G12; the feedback signal A-N-N is mapped into G15; the feedback signal A-A-N is mapped into G5; the 15 feedback signal D-D-A is mapped into G1; the feedback signal D-N-A is mapped into G14; the feedback signal D-A-A is mapped into G7; the feedback signal N-D-A is mapped into H4; the feedback signal N-N-A is mapped into H5; the feedback signal N-A-A is mapped into Gl; the feedback signal A-D-A is mapped into H10; the feedback signal A-N-A is mapped into G9; and the feedback signal A-A-A is mapped into G13. 20 Still further, in this embodiment, codeword values, namely bit sequences, corresponding to each codeword are provided, and mapping relationships between codewords and bit sequences may 16 be referred to Table 1-11. As can be seen from Table 1-11, the codebook comprises 26 codeword values with the smallest code distance of 4. Table 1-11 Mapping Relationships Between Codewords And Bit Sequences Codeword Bit sequence GI 1 0 0 0 1 0 1 0 1 0 G2 0 0 1 1 1 0 0 0 0 1 G3 1 1 1 1 1 1 1 1 1 1 G4 1 0 1 0 0 1 0 1 0 0 G5 1 1 1 1 0 0 0 1 1 0 G6 1 1 1 0 0 1 1 0 0 1 G7 0 0 1 0 0 1 0 0 1 1 G8 0 0 1 1 0 0 1 1 0 0 G9 0 1 1 0 1 0 1 1 0 1 G1O 0 1 1 1 1 1 0 0 1 0 G11 0 1 0 1 0 1 1 0 0 0 G12 0 1 0 0 0 0 0 1 1 1 G13 1 0 0 1 1 1 0 1 0 1 G14 0 0 1 0 1 1 1 1 1 0 G15 1 1 1 0 1 0 0 0 0 0 G16 1 0 1 1 0 0 1 0 1 1 HI 0 1 1 1 0 1 0 1 0 1 H2 1 1 0 0 0 1 1 1 1 0 H3 0 0 0 0 0 0 0 0 0 0 H4 0 1 0 1 1 0 1 0 1 1 H5 0 0 0 0 1 1 1 0 0 1 H6 0 0 0 1 1 0 0 1 1 0 H7 1 1 0 1 1 0 1 1 0 0 H8 1 1 0 0 1 1 0 0 1 1 H9 1 0 0 1 0 1 0 0 1 0 HIO 1 0 0 0 0 0 1 1 0 1 Table 1-11 is a specific example. The present invention is not limited to merely the mapping 5 relationships shown in Table 1-11, and those mapping relationships obtained by performing simple transformation on the basis of Table 1-11 also falls within the scope of the present invention, such as random changing of a sequence between columns on the basis of Table 1-11, or negation of a certain column value. This embodiment provides a method for encoding feedback signals of three carriers in TC 10 mode. In this embodiment, a single code channel is applied, which not only reduces power overhead, increases system capacity, and improves system performance, but does not affect CM value. Furthermore, in this embodiment, codebook satisfying a particular code distance relationship is selected, and a mapping solution between feedback signals and codewords is provided, so that signal error detection costs (including Radio Link Control (RLC) re-transmission cost and physical 15 layer re-transmission cost) are minimized, thus improving data transmission efficiency. 17 Embodiment 2 of a method for encoding feedback signals The method of this embodiment includes: encoding feedback signals of three carriers to output a bit sequence, and transmitting the bit sequence on a HS-DPCCH. The encoding the feedback signals of the three carriers may specifically include: mapping the 5 feedback signals of the three carriers into a codeword selected from a codebook. The codebook satisfies a particular code distance relationship, which may be acquired through computer searching or by using other methods. Under a condition that a certain requirement (such as compatibility) is satisfied, a principle of selecting a codebook is that the smallest code distance is maximized, and the number of the smallest code distances is minimized. 0 Specifically, the codebook in this embodiment includes 24 codewords in total, and these codewords are selected from the codebook comprising codewords Al to A6, B1 to B6, C1 to C6, and D1 to D6. For code distance relationships between the codewords, reference can be made to Table 1-12. Table 1-12 Code Distance Relationships Between Codewords Al A2 A3 A4 A5 A6 BI B2 B3 B4 B5 B6 C1 C2 C3 C4 C5 C6 D1 D2 D3 D4 D5 D6 Al 0 6 6 6 6 6 10 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A2 6 0 6 6 6 6 4 10 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A3 6 6 0 6 6 6 4 4 10 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A4 6 6 6 0 6 6 4 4 4 10 4 4 5 5 5 5 5 5 5 5 5 5 5 5 A5 6 6 6 6 0 6 4 4 4 4 10 4 5 5 5 5 5 5 5 5 5 5 5 5 A6 6 6 6 6 6 0 4 4 4 4 4 10 5 5 5 5 5 5 5 5 5 5 5 5 BI 10 4 4 4 4 4 0 6 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B2 4 10 4 4 4 4 6 0 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B3 4 4 10 4 4 4 6 6 0 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B4 4 4 4 10 4 4 6 6 6 0 6 6 5 5 5 5 5 5 5 5 5 5 5 5 B5 4 4 4 4 10 4 6 6 6 6 0 6 5 5 5 5 5 5 5 5 5 5 5 5 B6 4 4 4 4 4 10 6 6 6 6 6 0 5 5 5 5 5 5 5 5 5 5 5 5 Cl 5 5 5 5 5 5 5 5 5 5 5 5 0 6 6 6 6 6 10 4 4 4 4 4 C2 5 5 5 5 5 5 5 5 5 5 5 5 6 0 6 6 6 6 4 10 4 4 4 4 C3 5 5 5 5 5 5 5 5 5 5 5 5 6 6 0 6 6 6 4 4 10 4 4 4 C4 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 0 6 6 4 4 4 10 4 4 C5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 0 6 4 4 4 4 10 4 18 C6 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 0 4 4 4 4 4 10 D1 5 5 5 5 5 5 5 5 5 5 5 5 10 4 4 4 4 4 0 6 6 6 6 6 D2 5 5 5 5 5 5 5 5 5 5 5 5 4 10 4 4 4 4 6 0 6 6 6 6 D3 5 5 5 5 5 5 5 5 5 5 5 5 4 4 10 4 4 4 6 6 0 6 6 6 D4 5 5 5 5 5 5 5 5 5 5 5 5 4 4 4 10 4 4 6 6 6 0 6 6 D5 5 5 5 5 5 5 5 5 5 5 5 5 4 4 4 4 10 4 6 6 6 6 0 6 D6 5 5 5 5 5 5 5 5 5 5 5 5 4 4 4 4 4 10 6 6 6 6 6 0 A value in Table 1-12 represents a code distance between two codewords, for example, the code distance between Al and Al is 0, the code distance between Al and A2 is 6, the code distance between Al and B1 is 10, and so on. Further, for the mapping a feedback signal into a codeword selected from the codebook, 5 reference can be made to Table 1-13. Table 1-13 Mapping Solution Between Feedback Signals And Codewords Carrier 2 Carrier 3 Carrier 1 DX NC C DTX NACK ACK DTX * D1 C1 DTX NACK B1 C2 A2 ACK Al B2 D2 DTX A3 C2 C5 NACK NACK D6 C2 A5 ACK D4 A4 B6 DTX B3 C3 C4 ACK NACK D5 A6 B4 ACK D3 B5 C6 It can be seen from Table 1-13 that, in this embodiment, the feedback signal D-N-D is mapped into Dl; the feedback signal D-A-D is mapped into Cl; the feedback signal N-D-D is mapped into B 1; the feedback signal N-N-D is mapped into C2; the feedback signal N-A-D is mapped into A2; 10 the feedback signal A-D-D is mapped into Al; the feedback signal A-N-D is mapped into B2; the feedback signal A-A-D is mapped into D2; the feedback signal D-D-N is mapped into A3; the feedback signal D-N-N is mapped into C2; the feedback signal D-A-N is mapped into C5; the feedback signal N-D-N is mapped into D6; the feedback signal N-N-N is mapped into C2; the feedback signal N-A-N is mapped into A5; the feedback signal A-D-N is mapped into D4; the 15 feedback signal A-N-N is mapped into A4; the feedback signal A-A-N is mapped into B6; the feedback signal D-D-A is mapped into B3; the feedback signal D-N-A is mapped into C3; the 19 feedback signal D-A-A is mapped into C4; the feedback signal N-D-A is mapped into D5; the feedback signal N-N-A is mapped into A6; the feedback signal N-A-A is mapped into B4; the feedback signal A-D-A is mapped into D3; the feedback signal A-N-A is mapped into B5; and the feedback signal A-A-A is mapped into C6. 5 Referring to Table 1-13, in this embodiment, some feedback signals are encoded into the same codeword, for example, the feedback signals N-N-D, D-N-N, and N-N-N are all encoded into C2. During decoding procedure, the Node B may select a decoding space according to a sending mode, and decodes the feedback signals in the decoding space, so that when the sending mode is Modes 1 to 6, a codeword transmitted in this embodiment is capable of being correctly decoded; when the 0 sending mode is Mode 7, and the Node B decodes a feedback signal to obtain a codeword C2, it is decided that the feedback signal is N-N-N. Still further, in this embodiment, codeword values, namely bit sequences, corresponding to each codeword are provided, and mapping relationships between codewords and bit sequences may be referred to Table 1-14. As can be seen from Table 1-14, the codebook comprises 24 codeword 5 values. Table 1-14 Mapping Relationships Between Codewords And Bit Sequences Codeword Bit sequence Al 1 1 1 1 1 1 1 1 1 1 A2 0 0 1 1 0 0 1 1 0 0 A3 1 1 0 0 0 1 1 0 0 0 A4 1 0 0 1 0 0 0 0 1 1 A5 0 1 0 0 1 0 0 1 1 0 A6 0 0 1 0 1 1 0 0 0 1 BI 0 0 0 0 0 0 0 0 0 0 B2 1 1 0 0 1 1 0 0 1 1 B3 0 0 1 1 1 0 0 1 1 1 B4 0 1 1 0 1 1 1 1 0 0 B5 1 0 1 1 0 1 1 0 0 1 B6 1 1 0 1 0 0 1 1 1 0 C1 1 1 1 1 1 0 0 0 0 0 C2 0 1 0 1 0 1 0 1 0 1 C3 0 1 1 0 0 0 1 0 1 1 C4 1 0 1 0 0 1 0 1 1 0 C5 0 0 0 1 1 1 1 0 1 0 C6 1 0 0 0 1 0 1 1 0 1 D1 0 0 0 0 0 1 1 1 1 1 D2 1 0 1 0 1 0 1 0 1 0 D3 1 0 0 1 1 1 0 1 0 0 D4 0 1 0 1 1 0 1 0 0 1 D5 1 1 1 0 0 0 0 1 0 1 D6 0 1 1 1 0 1 0 0 1 0 Table 1-14 is a specific example. The present invention is not limited to merely the mapping 20 relationships shown in Table 1-14, and those mapping relationships obtained by performing simple transformation on the basis of Table 1-14 also falls within the scope of the present invention, such as random changing of a sequence between columns on the basis of Table 1-14, or negation of a certain column value. 5 In this embodiment, 26 feedback signals are encoded with 24 codewords, and when the sending mode is Mode 7, a decoding error may occur to the Node B, for example, the feedback signal N-N-D or D-N-N of the UE is decoded into N-N-N, such that a bit error rate is affected. However, since fewer codewords are adopted, the entire system performance can be improved. In a scenario of a higher requirement of the system performance, this embodiment has good 0 applicability. This embodiment provides a method for encoding feedback signals of three carriers in TC mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. Embodiment 3 of a method for encoding feedback signals 5 A difference between this embodiment and Embodiment 2 lies in a mapping solution between feedback signals and codewords. For the mapping solution of this embodiment, reference can be made to Table 1-15. It can be seen from Table 1-15 that, in this embodiment, the feedback signal D-N-D is mapped into Dl; the feedback signal D-A-D is mapped into Cl; the feedback signal N-D-D is mapped into 0 B 1; the feedback signal N-N-D is mapped into C2; the feedback signal N-A-D is mapped into A2; the feedback signal A-D-D is mapped into Al; the feedback signal A-N-D is mapped into B2; the feedback signal A-A-D is mapped into D2; the feedback signal D-D-N is mapped into A3; the feedback signal D-N-N is mapped into C5; the feedback signal D-A-N is mapped into C4; the feedback signal N-D-N is mapped into C2; the feedback signal N-N-N is mapped into C2; the 25 feedback signal N-A-N is mapped into A5; the feedback signal A-D-N is mapped into D3; the feedback signal A-N-N is mapped into A4; the feedback signal A-A-N is mapped into B6; the feedback signal D-D-A is mapped into B3; the feedback signal D-N-A is mapped into B4; the feedback signal D-A-A is mapped into D5; the feedback signal N-D-A is mapped into C3; the feedback signal N-N-A is mapped into D4; the feedback signal N-A-A is mapped into D6; the 30 feedback signal A-D-A is mapped into B5; the feedback signal A-N-A is mapped into A6; and the feedback signal A-A-A is mapped into C6. 21 Table 1-15 Mapping Solution Between Feedback Signals And Codewords Carrier 2 Carrier 3 Carrier 1 DX NC C DTX NACK ACK DTX * D1 C1 DTX NACK BI C2 A2 ACK Al B2 D2 DTX A3 C5 C4 NACK NACK C2 C2 A5 ACK D3 A4 B6 DTX B3 B4 D5 ACK NACK C3 D4 D6 ACK B5 A6 C6 Code distance relationships between codewords and mapping relationships between codewords and codeword values according to this embodiment may be the same as those in Embodiment 2, with reference to Tables 1-12 and 1-14. 5 Referring to Table 1-15, in this embodiment, also, some feedback signals are encoded into the same codeword, for example, the feedback signals N-N-D, N-D-N, and N-N-N are all encoded into C2. During decoding procedure, the Node B may select a decoding space according to a sending mode, and perform decoding procedure in the decoding space, so that when the sending mode is Modes 1 to 6, a codeword transmitted in this embodiment is capable of being correctly decoded; 0 while when the sending mode is Mode 7, and the Node B decodes a feedback signal to obtain a codeword C2, it is decided that the feedback signal is N-N-N. In this embodiment, 26 feedback signals are encoded with 24 codewords, and when the sending mode is Mode 7, a decoding error may occur to the Node B, for example, the feedback signal N-N-D or N-D-N of the UE is decoded into N-N-N, such that a bit error rate is affected. 15 However, since fewer codewords are adopted, the entire system performance can be improved. In a scenario of a higher requirement of the system performance, this embodiment has good applicability. This embodiment provides a method for encoding feedback signals of three carriers in TC mode. In this embodiment, a single code channel is applied, which not only reduces power overhead 20 and improves system performance, but does not affect CM value. Embodiment 4 of a method for encoding feedback signals A difference between this embodiment and Embodiment 2 lies in a mapping solution between feedback signals and codewords. For the mapping solution of this embodiment, reference can be 22 made to Table 1-16. Table 1-16 Mapping Solution Between Feedback signals And Codewords Carrier 2 Carrier 3 Carrier 1 DX NC C DTX NACK ACK DTX * D1 C1 DTX NACK BI C2 C5 ACK Al A4 D3 DTX A3 A2 C4 NACK NACK C2 C2 A5 ACK D3 B2 B6 DTX B3 B4 D4 ACK NACK D4 C3 D6 ACK B5 A6 C6 It can be seen from Table 1-16 that, the feedback signal D-N-D is mapped into Dl; the feedback signal D-A-D is mapped into Cl; the feedback signal N-D-D is mapped into B 1; the 5 feedback signal N-N-D is mapped into C2; the feedback signal N-A-D is mapped into C5; the feedback signal A-D-D is mapped into Al; the feedback signal A-N-D is mapped into A4; the feedback signal A-A-D is mapped into D3; the feedback signal D-D-N is mapped into A3; the feedback signal D-N-N is mapped into A2; the feedback signal D-A-N is mapped into C4; the feedback signal N-D-N is mapped into C2; the feedback signal N-N-N is mapped into C2; the 0 feedback signal N-A-N is mapped into A5; the feedback signal A-D-N is mapped into D3; the feedback signal A-N-N is mapped into B2; the feedback signal A-A-N is mapped into B6; the feedback signal D-D-A is mapped into B3; the feedback signal D-N-A is mapped into B4; the feedback signal D-A-A is mapped into D4; the feedback signal N-D-A is mapped into D4; the feedback signal N-N-A is mapped into C3; the feedback signal N-A-A is mapped into D6; the 15 feedback signal A-D-A is mapped into B5; the feedback signal A-N-A is mapped into A6; and the feedback signal A-A-A is mapped into C6. Code distance relationships between codewords and mapping relationships between codewords and codeword values according to this embodiment may be the same as those in Embodiment 2, with reference to Tables 1-12 and 1-14. 20 Referring to Table 1-16, in this embodiment, also, some feedback signals are encoded with the same codeword, for example, the feedback signals N-N-D, N-D-N, and N-N-N are all encoded into C2. During decoding procedure, the Node B may select a decoding space according to a sending mode, and perform decoding procedure in the decoding space, so that when the sending mode is Modes 1 to 6, a codeword transmitted in this embodiment is capable of being correctly decoded; 23 while when the sending mode is Mode 7, and the Node B decodes a feedback signal to obtain a codeword C2, it is decided that the feedback signal is N-N-N. In this embodiment, 26 feedback signals are encoded with 24 codewords, and when the sending mode is Mode 7, a decoding error may occur to the Node B, for example, the feedback 5 signal N-N-D or N-D-N of the UE is decoded into N-N-N, such that a bit error rate is affected. However, since fewer codewords are adopted, the entire system performance can be improved. In a scenario of a higher requirement of the system performance, this embodiment has good applicability. This embodiment provides a method for encoding feedback signals of three carriers in TC 0 mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. Embodiment 5 of a method for encoding feedback signals The method of this embodiment includes: encoding feedback signals of three carriers to output a bit sequence, and sending the bit sequence on a HS-DPCCH. 5 The encoding the feedback signals of the three carriers may specifically include: mapping the feedback signals of the three carriers into a codeword selected from a codebook. The codebook satisfies a particular code distance relationship, which may be acquired through computer searching or by using other methods. Under a condition that a certain requirement (such as compatibility) is satisfied, a principle of selecting a codebook is that the smallest code distance is maximized, and the 0 number of the smallest code distances is minimized. Specifically, the codebook selected in this embodiment includes 26 codewords in total, and these codewords are selected from the codebook comprising codewords Al to A6, B1 to B6, C1 to C6, D1 to D6, El, and Fl. For code distance relationships between the codewords, reference can be made to Tables 1-12 and 1-17. 25 Table 1-17 Code Distance Relationships Between Codewords Al A2 A3 A4 A5 A6 B1 B2 B3 B4 B5 B6 C1 C2 C3 C4 C5 C6 D1 D2 D3 D4 D5 D6 El F1 El 6 6 6 4 4 4 4 4 4 6 6 6 7 7 3 7 3 3 3 3 7 3 7 7 0 10 F1 4 4 4 6 6 6 6 6 6 4 4 4 3 3 7 3 7 77 7 3 7 3 3 10 0 Further, for the mapping a feedback signal into a codeword selected from the codebook, reference can be made to Table 1-18. 24 Table 1-18 Mapping Solution Between Feedback Signals And Codewords Carrier 2 Carrier 3 Carrier 1 DX NC C DTX NACK ACK DTX * D1 C1 DTX NACK BI C2 A2 ACK Al B2 D2 DTX B3 El C4 NACK NACK D3 F1 A5 ACK D4 A6 B4 DTX A3 C3 D6 ACK NACK C5 C6 D5 ACK B5 A4 B6 It can be seen from Table 1-18 that, in this embodiment, the feedback signal D-N-D is mapped into Dl; the feedback signal D-A-D is mapped into Cl; the feedback signal N-D-D is mapped into B 1; the feedback signal N-N-D is mapped into C2; the feedback signal N-A-D is mapped into A2; 5 the feedback signal A-D-D is mapped into Al; the feedback signal A-N-D is mapped into B2; the feedback signal A-A-D is mapped into D2; the feedback signal D-D-N is mapped into B3; the feedback signal D-N-N is mapped into El; the feedback signal D-A-N is mapped into C6; the feedback signal N-D-N is mapped into D3; the feedback signal N-N-N is mapped into Fl; the feedback signal N-A-N is mapped into A5; the feedback signal A-D-N is mapped into D6; the 0 feedback signal A-N-N is mapped into A6; the feedback signal A-A-N is mapped into B4; the feedback signal D-D-A is mapped into A3; the feedback signal D-N-A is mapped into C3; the feedback signal D-A-A is mapped into D5; the feedback signal N-D-A is mapped into C4; the feedback signal N-N-A is mapped into C5; the feedback signal N-A-A is mapped into D4; the feedback signal A-D-A is mapped into B5; the feedback signal A-N-A is mapped into A4; and the 15 feedback signal A-A-A is mapped into B6. Still further, in this embodiment, codeword values corresponding to each codeword are provided, and the codeword values are bit sequences which may be referred to Table 1-19. As can be seen from Table 1-19, the codebook comprises the 26 codeword values with the smallest code distance of 3. 20 Table 1-19 Mapping Relationships Between Codewords And Bit Sequences Codeword Bit sequence Al 1 1 1 1 1 1 1 1 1 1 A2 0 0 1 1 0 0 1 1 0 0 A3 1 1 0 0 0 1 1 0 0 0 A4 1 0 0 1 0 0 0 0 1 1 25 A5 0 1 0 0 1 0 0 1 1 0 A6 0 0 1 0 1 1 0 0 0 1 B1 0 0 0 0 0 0 0 0 0 0 B2 1 1 0 0 1 1 0 0 1 1 B3 0 0 1 1 1 0 0 1 1 1 B4 0 1 1 0 1 1 1 1 0 0 B5 1 0 1 1 0 1 1 0 0 1 B6 1 1 0 1 0 0 1 1 1 0 C1 1 1 1 1 1 0 0 0 0 0 C2 0 1 0 1 0 1 0 1 0 1 C3 0 1 1 0 0 0 1 0 1 1 C4 1 0 1 0 0 1 0 1 1 0 C5 0 0 0 1 1 1 1 0 1 0 C6 1 0 0 0 1 0 1 1 0 1 D1 0 0 0 0 0 1 1 1 1 1 D2 1 0 1 0 1 0 1 0 1 0 D3 1 0 0 1 1 1 0 1 0 0 D4 0 1 0 1 1 0 1 0 0 1 D5 1 1 1 0 0 0 0 1 0 1 D6 0 1 1 1 0 1 0 0 1 0 El 0 0 0 0 1 0 1 0 1 1 F1 1 1 1 1 0 1 0 1 0 0 Table 1-19 is a specific example. The present invention is not limited to merely the mapping relationships shown in Table 1-19, and those mapping relationships obtained by performing simple transformation on the basis of Table 1-19 also falls within the scope of the present invention, such as random changing of a sequence between columns on the basis of Table 1-19, or negation of a 5 certain column value. This embodiment provides a method for encoding feedback signals of three carriers in TC mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. Embodiment 6 of a method for encoding feedback signals 10 A difference between this embodiment and Embodiment 5 lies in a mapping solution between feedback signals and codewords. For the mapping solution of this embodiment, reference can be made to Table 1-20. Table 1-20 Mapping Solution Between Feedback Signals And Codewords Carrier 3 Carrier 1 Carrier 2 DTX NACK ACK DTX * A2 B2 DTX NACK BI El D2 ACK Al C5 B4 NACK DTX A3 F1 C1 26 NACK C2 C6 D5 ACK C4 A6 D3 DTX B3 C3 B6 ACK NACK B5 D4 A4 ACK D6 D1 A5 It can be seen from Table 1-20 that, in this embodiment, the feedback signal D-N-D is mapped into A2; the feedback signal D-A-D is mapped into B2; the feedback signal N-D-D is mapped into B 1; the feedback signal N-N-D is mapped into E1; the feedback signal N-A-D is mapped into D2; the feedback signal A-D-D is mapped into Al; the feedback signal A-N-D is mapped into C5; the 5 feedback signal A-A-D is mapped into B4; the feedback signal D-D-N is mapped into A3; the feedback signal D-N-N is mapped into Fl; the feedback signal D-A-N is mapped into C1; the feedback signal N-D-N is mapped into C2; the feedback signal N-N-N is mapped into C6; the feedback signal N-A-N is mapped into D5; the feedback signal A-D-N is mapped into C4; the feedback signal A-N-N is mapped into A6; the feedback signal A-A-N is mapped into D3; the 0 feedback signal D-D-A is mapped into B3; the feedback signal D-N-A is mapped into C3; the feedback signal D-A-A is mapped into B6; the feedback signal N-D-A is mapped into B5; the feedback signal N-N-A is mapped into D4; the feedback signal N-A-A is mapped into A4; the feedback signal A-D-A is mapped into D6; the feedback signal A-N-A is mapped into D1; and the feedback signal A-A-A is mapped into A5. 5 Code distance relationships between codewords and mapping relationships between codewords and codeword values according to this embodiment may be the same as those in Embodiment 5 of the method for encoding feedback signals, with reference to Tables 1-12 and 1-17. This embodiment provides a method for encoding feedback signals of three carriers in TC mode. In this embodiment, a single code channel is applied, which not only reduces power overhead 20 and improves system performance, but does not affect CM value. Embodiment 7 of a method for encoding feedback signals The method of this embodiment includes: encoding feedback signals of three carriers to output a bit sequence, and transmitting the bit sequence on a HS-DPCCH. The encoding the feedback signals of the three carriers may specifically include: mapping the 25 feedback signals of the three carriers into a codeword selected from a codebook. The codebook satisfies a particular code distance relationship, which may be acquired through computer searching or by using other methods. Under a condition that a certain requirement (such as compatibility) is satisfied, a principle of selecting a codebook is that the smallest code distance is maximized, and the number of the smallest code distances is minimized. 27 Specifically, the codebook selected in this embodiment includes 26 codewords in total, and these codewords are selected from the codebook comprising codewords Al to A6, B1 to B6, C1 to C6, D1 to D6, El, and Fl. For code distance relationships between the codewords, reference can be made to Table 1-21. 5 Table 1-21 Code Distance Relationships Between Codewords Al A2 A3 A4 A5 A6 BI B2 B3 B4 B5 B6 C1 C2 C3 C4 C5 C6 D1 D2 D3 D4 D5 D6 E2 F2 Al 0 6 6 6 6 610 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 7 3 A2 6 0 6 6 6 6 4 10 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 A3 6 6 0 6 6 6 4 4 10 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 A4 6 6 6 0 6 6 4 4 4 10 4 4 5 5 5 5 5 5 5 5 5 5 5 5 3 7 A5 6 6 6 6 0 6 4 4 4 4 10 4 5 5 5 5 5 5 5 5 5 5 5 5 7 3 A6 6 6 6 6 6 0 4 4 4 4 4 10 5 5 5 5 5 5 5 5 5 5 5 5 3 7 BI 10 4 4 4 4 4 0 6 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 3 7 B2 4 10 4 4 4 4 6 0 6 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 5 5 B3 4 4 10 4 4 4 6 6 0 6 6 6 5 5 5 5 5 5 5 5 5 5 5 5 5 B4 4 4 4 10 4 4 6 6 6 0 6 6 5 5 5 5 5 5 5 5 5 5 5 5 7 3 B5 4 4 4 4 10 4 6 6 6 6 0 6 5 5 5 5 5 5 5 5 5 5 5 5 3 7 B6 4 4 4 4 4 10 6 6 6 6 6 0 5 5 5 5 5 5 5 5 5 5 5 5 7 3 C1 5 5 5 5 5 5 5 5 5 5 5 5 0 6 6 6 6 6 10 4 4 4 4 4 6 4 C2 5 5 5 5 5 5 5 5 5 5 5 5 6 0 6 6 6 6 4 104 4 4 4 2 8 C3 5 5 5 5 5 5 5 5 5 5 5 5 6 6 0 6 6 6 4 4 10 4 4 4 6 4 C4 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 0 6 6 4 4 4 10 4 4 6 4 C5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 0 6 4 4 4 4 10 4 4 6 C6 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 0 4 4 4 4 4 10 6 4 D1 5 5 5 5 5 5 5 5 5 5 5 5 10 4 4 4 4 4 0 6 6 6 6 6 4 6 D2 5 5 5 5 5 5 5 5 5 5 5 5 4 10 4 4 4 4 6 0 6 6 6 6 8 2 D3 5 5 5 5 5 5 5 5 5 5 5 5 4 4 10 4 4 4 6 6 0 6 6 6 4 6 D4 5 5 5 5 5 5 5 5 5 5 5 5 4 4 4 10 4 4 6 6 6 0 6 6 4 6 D5 5 5555 5 4 4 4 4 10 4 6 6 6 6 0 6 6 4 D6 5 5 5 5 5 5 5 5 5 5 4 4 10 6 6 660 4 6 E2 7 5 5 3 7 3 3 5 5 7 3 7 6 2 6 6 4 6 4 8 4 4 6 4 0 10 F2 3557377 5 5 37 3 48 4464626 6 4100 Further, for the mapping a feedback signal into a codeword selected from the codebook, reference can be made to Table 1-22. Table 1-22 Mapping Solution Between Feedback Signals And Codewords Carrier 2 Carrier 3 Carrier 1 DX NC C DTX NACK ACK DTX * D1 C1 DTX NACK BI C2 A2 ACK Al B2 D2 DTX B6 C5 C6 NACK NACK D4 E2 A3 ACK D3 A5 F2 28 DTX A6 C4 C3 ACK NACK D5 A4 B5 ACK D6 B3 B4 It can be seen from Table 1-22 that, in this embodiment, the feedback signal D-N-D is mapped into Dl; the feedback signal D-A-D is mapped into Cl; the feedback signal N-D-D is mapped into B 1; the feedback signal N-N-D is mapped into C2; the feedback signal N-A-D is mapped into A2; the feedback signal A-D-D is mapped into Al; the feedback signal A-N-D is mapped into B2; the 5 feedback signal A-A-D is mapped into D2; the feedback signal D-D-N is mapped into B6; the feedback signal D-N-N is mapped into C5; the feedback signal D-A-N is mapped into C6; the feedback signal N-D-N is mapped into D4; the feedback signal N-N-N is mapped into E2; the feedback signal N-A-N is mapped into A3; the feedback signal A-D-N is mapped into D3; the feedback signal A-N-N is mapped into A5; the feedback signal A-A-N is mapped into F2; the 0 feedback signal D-D-A is mapped into A6; the feedback signal D-N-A is mapped into C4; the feedback signal D-A-A is mapped into C3; the feedback signal N-D-A is mapped into D5; the feedback signal N-N-A is mapped into A4; the feedback signal N-A-A is mapped into B5; the feedback signal A-D-A is mapped into D6; the feedback signal A-N-A is mapped into B3; and the feedback signal A-A-A is mapped into B4. 5 Still further, in this embodiment, codeword values corresponding to each codeword are provided, and the codeword values are bit sequences which may be referred to Table 1-23. As can be seen from Table 1-23, the codebook comprises 26 codeword values. Table 1-23 Mapping Relationships Between Codewords And Bit Sequences Codeword Bit sequence Al 1 1 1 1 1 1 1 1 1 1 A2 0 0 1 1 0 0 1 1 0 0 A3 1 1 0 0 0 1 1 0 0 0 A4 1 0 0 1 0 0 0 0 1 1 A5 0 1 0 0 1 0 0 1 1 0 A6 0 0 1 0 1 1 0 0 0 1 B1 0 0 0 0 0 0 0 0 0 0 B2 1 1 0 0 1 1 0 0 1 1 B3 0 0 1 1 1 0 0 1 1 1 B4 0 1 1 0 1 1 1 1 0 0 B5 1 0 1 1 0 1 1 0 0 1 B6 1 1 0 1 0 0 1 1 1 0 C1 1 1 1 1 1 0 0 0 0 0 C2 0 1 0 1 0 1 0 1 0 1 C3 0 1 1 0 0 0 1 0 1 1 C4 1 0 1 0 0 1 0 1 1 0 C5 0 0 0 1 1 1 1 0 1 0 C6 1 0 0 0 1 0 1 1 0 1 D1 0 0 0 0 0 1 1 1 1 1 29 D2 1 0 1 0 1 0 1 0 1 0 D3 1 0 0 1 1 1 0 1 0 0 D4 0 1 0 1 1 0 1 0 0 1 D5 1 1 1 0 0 0 0 1 0 1 D6 0 1 1 1 0 1 0 0 1 0 E2 0 0 0 1 0 1 0 0 0 1 F2 1 1 1 0 1 0 1 1 1 0 Table 1-23 is a specific example. The present invention is not limited to merely the mapping relationships shown in Table 1-23, and those mapping relationships obtained by performing simple transformation on the basis of Table 1-23 also falls within the scope of the present invention, such as random changing of a sequence between columns on the basis of Table 1-23, or negation of a 5 certain column value. This embodiment provides a method for encoding feedback signals of three carriers in TC mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. In view of the foregoing, the present invention provides solutions for HARQ-ACK technology 0 in TC mode. According to the foregoing description, the present invention is further applicable to double code channels, which solves HARQ-ACK feedback problems of 4 carriers, 5 carriers, and 6 carriers. For ease of description, in the embodiments of the present invention, definitions of the following terms are specified as follows: 5 SC: an encoding solution for single-carrier, that is, the encoding solution corresponding to Table 1-1; DC: an encoding solution for dual-carrier, that is, the encoding solution corresponding to Table 1-2; TC: an encoding solution for ternary-carrier, that is, the encoding solution according to the 20 present invention; for 4 carriers: the TC encoding solution may be applied in a first code channel, and the SC encoding solution may be applied in a second code channel; for 5 carriers: the TC encoding solution may be applied in a first code channel, and the DC encoding solution may be applied in a second code channel; and for 6 carriers: the TC encoding solution may be applied in a first code channel, 25 and the TC encoding solution may also be applied in a second code channel. Embodiment 1 of an apparatus for encoding feedback signal FIG. 3 is a schematic structure of an apparatus for encoding feedback signal according to Embodiment 1 of the present invention. As shown in FIG. 3, the apparatus includes an encoder 1 30 and a transmitter 2. The encoder 1 is configured to encode feedback signals of three carriers to output a bit sequence, and the transmitter 2 is configured to transmit the bit sequence on a HS-DPCCH. In this embodiment, the encoder 1 is further configured to map the feedback signals of the 5 three carriers into a codeword. The codeword is selected from the codebook comprising codewords G1 to G16 and H1 to H10. For code distance relationships between the codewords in the codebook, reference can be made to Table 1-9. Specifically, in this embodiment, the encoder 1 may perform the encoding procedure according to the description in Embodiment 1 of method for encoding feedback signals aforementioned. 0 This embodiment provides an apparatus for encoding feedback signals of three carriers in TC mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. Embodiment 2 of an apparatus for encoding feedback signals The apparatus according to this embodiment may include an encoder and a transmitter. The 5 encoder is configured to encode feedback signals of three carriers to output a bit sequence, and the transmitter is configured to transmit the bit sequence on a HS-DPCCH. In this embodiment, the encoder is further configured to map the feedback signals of the three carriers into a codeword selected from a codebook. The codebook comprises codewords Al to A6, B1 to B6, C1 to C6, and D1 to D6. For code distance relationships between the codewords, 0 reference can be made to Table 1-12. Specifically, in this embodiment, the encoder 1 may perform the encoding procedure according to the description in Embodiment 2 to Embodiment 4 of the method for encoding feedback signals aforementioned. This embodiment provides an apparatus for encoding feedback signals of three carriers in TC 25 mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. Embodiment 3 of an apparatus for encoding feedback signals The apparatus according to this embodiment may include an encoder and a transmitter. The encoder is configured to encode feedback signals of three carriers to output a bit sequence, and 30 transmitter is configured to transmit the bit sequence on a HS-DPCCH. In this embodiment, the encoder is further configured to map the feedback signals of the three carriers into a codeword selected from a codebook. The codebook comprises codewords Al to A6, 31 B1 to B6, C1 to C6, D1 to D6, El, and Fl. For code distance relationships between the codewords in the codebook, reference can be made to Table 1-17. Specifically, in this embodiment, the encoder 1 may perform the encoding procedure according to the description in Embodiment 5 and Embodiment 6 of the method for encoding feedback 5 signals. This embodiment provides an apparatus for encoding feedback signals of three carriers in TC mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. Embodiment 4 of an apparatus for encoding feedback signals 0 The apparatus according to this embodiment may include an encoder and a transmitter. The encoder is configured to encode feedback signals of three carriers to output a bit sequence, and the transmitter is configured to transmit the bit sequence on a HS-DPCCH. In this embodiment, the encoder is configured to map the feedback signals of the three carriers into a codeword selected from a codebook. The codebook comprises codewords Al to A6, B 1 to B6, 5 C1 to C6, D1 to D6, El, and Fl. For code distance relationships between the codewords in the codebook, reference can be made to Table 1-21. Specifically, in this embodiment, encoder 1 may perform the encoding procedure according to the description in Embodiment 7 of the method encoding feedback signal. This embodiment provides an apparatus for encoding feedback signals of three carriers in TC 0 mode. In this embodiment, a single code channel is applied, which not only reduces power overhead and improves system performance, but does not affect CM value. A Person skilled in the art may understand that all or part of the steps of the method according to the embodiments of the present invention may be implemented by a computer program code instructing hardware. The computer program code may be stored in a computer readable storage 25 medium. When the computer program code runs in a computer unit, the steps of the method according to the embodiments of the present invention are performed. The storage medium may be any medium that is capable of storing program codes, such as a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk. It should be noted that the above embodiments are merely provided for elaborating the 30 technical solutions of the present invention, but not intended to limit the present invention. 32