KR20010073237A - optimal method for transmitting TFCI - Google Patents

Abstract

PURPOSE: A method for transmitting an optimum TFCI(Transport Format Combination Indicator) is provided to enable a transmitting party to optimize the pattern of a transmission format information bit for encoding, and to enable a receiving party to decode the TFCI by a simple procedure. CONSTITUTION: Predetermined number of bits in transmission format information bits are shifted, and a corresponding coding is performed according to the bit number of the transmission format information bits. A codeword by the coding is punctured in a fixed bit position, and inserted in each slot of a wireless frame to be distributed, for transmission. The transmitted codeword is received. An optional bit value is applied to the punctured bit position in the received codeword, for de-puncturing. The de-punctured codeword is decoded, to restore an original transmission format information bit.

Description

Optimal method for transmitting TFCI

The present invention relates to the next generation mobile communication, and more particularly, to a method for receiving and decoding TFCI encoded and inserted for each time slot of a radio frame in a mobile communication system using a W-CDMA scheme.

In general, the Third Generation Partnership Project (3GPP) describes definitions and explanations of uplink and downlink physical channels.

Dedicated Physical Channels (DPCHs) of physical channels generally consist of three hierarchical structures: superframes, radio frames, and timeslots. The structure of the dedicated physical channel (DPCH) is shown.

There are two types of Dedicated Physical Channels (DPCHs), which are Dedicated Physical Data Channels (hereinafter referred to as DPDCHs) for delivering dedicated data and Dedicated Physical Control Channels for delivering control information. Physical Control Channel (hereinafter, abbreviated as DPCCH).

1 is a diagram illustrating a structure of an uplink dedicated physical channel (DPCH) according to a 3GPP radio access network (RAN) standard, and FIG. 2 is a diagram illustrating a structure of a downlink dedicated physical channel.

In FIG. 1 and FIG. 2, the DPCCH includes a TFCI field for each time slot constituting a radio frame. In each radio frame, TFCI bits of 10 bits or less are coded and inserted. In other words, transmission format information is coded and inserted into each radio frame.

The following describes the coding of TFCI bits according to the existing 3GPP standard.

The number of bits of TFCI varies from a minimum of 1 bit to a maximum of 10 bits, and the number of bits is determined at the start of a call by signal processing of a higher layer.

These TFCIs are applied with different coding schemes depending on the number of bits determined by higher layer signal processing. That is, when the TFCI bit is 6 bits or less, bi-orthogonal coding, which is the first Reed-muller coding, is applied. When the TFCI bit is 7 bits or more, the second read-muller coding is applied. Apply. In the second read-muller coding, the coded sub-code is punctured again to generate a 30-bit long codeword.

As an example of this, when the TFCI determined by the signal processing of the upper layer is 6 bits or less, the TFCI is output as a TFCI codeword through quadrature coding. For orthogonal coding, (32,6) coding is applied. For this, if the transmission format information bit for coding is less than 6 bits, the missing bit value is filled with the most significant bit (MSB) from "0". The padding procedure is first performed.

Since the orthogonal coded TFCI codeword is inserted into each time slot by 2 bits and then transmitted, the total length is fixed to 30 bits. Therefore, a 32-bit orthogonal coded TFCI codeword is punctured by 2 bits and then inserted into each time slot.

As an example, when the TFCI determined by the signal processing of the upper layer is 10 bits or less, the TFCI is output as a TFCI codeword through the second read-muller coding. The second lead-muller coding scheme (32, 10) coding is applied. For this, if the transmission format information bit for coding is less than 10 bits, padding that fills the missing bit value from the most significant bit (MSB) to " 0 " The padding process is done first.

The second read-muller coded TFCI codeword is called a sub-code, which generates a 30-bit long TFCI codeword after two bits are punctured. The channel coding procedure for this is shown in FIG. 3.

The 30-bit codeword generated in each of the above examples is divided into two bits and inserted into each time slot, and then transmitted. 4 is a diagram illustrating insertion of a general coded TFCI codeword into each timeslot.

FIG. 5 is a diagram illustrating an encoder structure for generating a (32,10) TFCI codeword by conventional second read-muller coding.

Referring to FIG. 5, an TFCI information bit that is variable from a minimum of 1 bit to a maximum of 10 bits is input to an encoder, and the input information bit is linearly combined with 10 basis sequences.

In this case, the basic sequence used for the linear combination is a single code whose all bit values are "1" and (C _32,1 , C _32,2 , C _32,4 , C shown in Table 1 below). Orthogonal variable spreading factor (hereinafter, abbreviated as OVSF) codes represented by _32,8 , C _32,16 ) and (Mask1, Mask2, Mask3, Mask4) shown in Table 2 below. It consists of four mask codes.

C _32,1 00000000000000001111111111111111 C _32,2 00000000111111110000000011111111 C _32,4 00001111000011110000111100001111 C _32,8 00110011001100110011001100110011 C _32,16 01010101010101010101010101010101

Mask1 00101000011000111111000001110111 Mask2 00000001110011010110110111000111 Mask3 00001010111110010001101100101011 Mask4 00011100001101110010111101010001

In addition, the TFCI information bits linearly combined with the base sequence are represented by Equation 1 below.

, Where n ≤ 10

In Equation 1, a ₀ is the least significant bit (LSB) and a _n-1 is the most significant bit (MSB).

After that, the TFCI codeword having a 30-bit length is output by puncturing the first bit and the 17th bit in the (32,10) subcode generated by the linear combination.

At this time, the 30-bit length TFCI codeword is expressed as shown in Equation 2 below.

However, in the TFCI encoding described so far, the pattern of the transport format information bits input for encoding was not appropriate because of the padding procedure that is performed when the transport format information bits input for coding are less than 10 bits.

More specifically, when the transmission format information bit for coding is less than 10 bits, it is generalized that a padding procedure of filling a missing bit value from the most significant bit (MSB) to "0" is generalized. Although the receiver can decode the transmitted TFCI codeword by a simpler procedure, there is still a problem of undergoing a complicated decoding procedure.

In particular, conventionally, even if the input transmission format information bit is less than 6 bits, the orthogonal coding is always performed. Therefore, the receiver determines whether the OVSF code used for encoding is selected from the two OVSF code sets that are binary complementary to each other. Priority detection is required and hardware is always required accordingly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above. In the present invention, the transmission side of the next-generation mobile communication system using the W-CDMA scheme is optimized after encoding a pattern of transmission format information bits, and the reception side A simpler procedure provides an optimal TFCI transmission method suitable for decoding TFCI.

A feature of the optimal TFCI transmission method according to the present invention for achieving the above object is the step of performing a predetermined coding according to the number of bits of the transmission format information bits after shifting a predetermined number of bits of the transmission format information bits And puncturing the codeword by the coding at a predetermined bit position, inserting the codeword into respective slots of the radio frame, and receiving the transmitted codeword, and receiving the puncture from the received codeword. Depunching by substituting an arbitrary bit value at the punctured bit position, decoding the depunctured codeword, and restoring the original transport format information bit.

Preferably, after the puncturing, the binary bit value of the punctured codeword is converted into a bipolar bit value and then transmitted.

In addition, when the transmission format information bit is less than a specific bit length, a predetermined bit string is made through padding from the most significant bit by a bit short of the predetermined bit length, and then the barrel is shifted to the bit string. Perform OVSF coding on the columns.

In particular, when the number of bits of the transport format information bits is less than 5 bits, the depuncturing step assigns a high-level bias value to the punctured bit positions, and when the number of bits of the transport format information bits is 5 bits. A high level bias value and a bit blank are substituted into the punctured bit positions, and when the number of bits of the transport format information bits exceeds 5 bits, a bit blank is substituted into the punctured bit positions.

Another feature of the optimal TFCI transmission method according to the present invention for achieving the above object is a linear combination of the code format and the OVSF code of the basic sequence with the input transmission format information bits, and the linear combination Puncturing the codeword at a predetermined bit position, and inserting the codeword into the slots of the radio frame, transmitting the codeword, and receiving the transmitted codeword, and at the punctured bit position in the received codeword. Depuncturing by assigning an arbitrary bias value or bit blank, and decoding the depunctured codeword to recover the original transport format information bits.

1 is a diagram illustrating a structure of an uplink dedicated physical channel (DPCH) according to a 3GPP radio access network (RAN) standard

2 is a diagram illustrating a structure of a downlink dedicated physical channel (DPCH) according to a 3GPP radio access network (RAN) standard;

3 is a block diagram illustrating channel coding for general transport format information bits.

4 shows the insertion of a generic coded TFCI codeword into each timeslot.

FIG. 5 illustrates an encoder structure for generating a (32,10) TFCI codeword by conventional second read-muller coding. FIG.

6 illustrates a transport format information bit pattern applied to TFCI encoding of the present invention.

7 is a diagram showing the structure of a TFCI transmitting side to which a transport format information bit pattern of the present invention is applied;

8 is a block diagram illustrating an optimal TFCI decoding procedure according to the present invention.

* Description of symbols on the main parts of the drawings *

10: depuncturing block 20: TFCI decoder

Hereinafter, a preferred embodiment of an optimal TFCI transmission method according to the present invention will be described with reference to the accompanying drawings.

Conventionally, first reed-muller coding, bi-orthogonal coding and second reed-muller coding, are applied according to the number of bits of the transport format information bits input for TFCI encoding. However, in the present invention, when the number of bits of the input transport format information bits is less than 6 bits, the bit pattern shown in FIG. 6 is applied so that only OVSF coding, not orthogonal coding, can be applied. Of course, when the number of bits of the transport format information bit is 6 bits or more, a different bit pattern is applied in some cases.

6 is a diagram illustrating a transport format information bit pattern applied to the TFCI encoding of the present invention, and FIG. 7 is a diagram illustrating a structure of a TFCI transmitter to which the transport format information bit pattern of the present invention is applied.

Referring to the transport format information bit pattern of FIG. 6, when the input transport format information bit is less than 6 bits, the bit value that is short from the most significant bit is different from the existing bit pattern so that only the OVSF coding is performed without the orthogonal coding. From a ₅ ), fill the "0" and then use the barrel shifted bit pattern as the input of the TFCI encoder. In addition, if the input transmission format information bit is 6 bits or more, the barrel-shifted bit pattern is input to the lower 6 bits from the existing bit pattern input to the TFCI encoder, and the upper 4 bits (mask code and linear in the basic sequence) are input. The combined transport format information bits) take the same bit pattern as the conventional input.

The hardware configuration for encoding and transmitting TFCI by applying the bit pattern of FIG. 6 is shown in FIG. 7A. In contrast, FIG. 7B inputs the existing transport format information bit pattern as it is, and replaces the arrangement of ten basic sequences that are linearly combined with the input information bit.

That is, in FIG. 7B, except for four mask codes (Mask1, Mask2, Mask3, and Mask4) among the basic sequences used for the linear combination, a code code having five bit values of "1" and five OVSF codes ( C _32,1 , C _32,2 , C _32,4 , C _32,8 , C _32,16 are barrel _shifted and linearly combined with the input information bits.

7A is a diagram illustrating a structure of a TFCI transmitting side according to the first embodiment of the present invention, and FIG. 7B is a diagram of a structure of a TFCI transmitting side according to a second embodiment of the present invention.

The transport format information bit pattern input to the TFCI encoder of FIG. 7A can be summarized as in Equation 3 below, and FIG. 6 shows the pattern of Equation 3. FIG.

(Where 1 ≦ i ≦ 10 and 0 ≦ j ≦ 9)

In Equation 3 above Is a set of 10 elements input to the TFCI encoder, that is, a vector representing each transport format information bit.

In the present invention, according to the pattern of the transport format information bit applied to each TFCI encoder and the basic sequence pattern of FIG. 7, the following coding is performed on each input in the TFCI encoder.

First, when the number of bits of the transport format information bits determined in the upper layer is less than 6 bits, OVSF coding is performed.

Second, when the number of bits of the transport format information bits determined in the upper layer is 6 bits, the quadrature coding, which is the first read-muller coding, is performed.

Third, when the number of bits of the transport format information bits determined in the upper layer exceeds 6 bits, the second read-muller coding is performed.

The 32-bit codeword generated by coding according to the number of input bits of each transport format information bit is then punctured by the first bit and the 17th bit to form a 30-bit codeword, which is then converted and transmitted again. do. The receiver then decodes it. In the punctured 30-bit codeword, a bit of "0" is converted to "1", and a bit of "1" is converted to "-1".

The following describes the principle of decoding with the transmission-side hardware structure of the present invention shown in FIG. 8 by using the TFCI encoder of FIG. 7 described above.

When the number of input bits of the transport format information bits is less than 6 bits when the bit pattern of FIG. 6 proposed in the present invention is applied, index conversion after Fast Hadamard Transform Decoding, which is generally performed at the receiving end, is performed. Explain why index conversion is not needed.

Mathematically, OVSF codes can be classified into codes generated using the Rademacher function. The Rademacher function R _n (t) is defined mathematically as shown in Equation 4 below.

, t`∈ (0, T), n = 1,2, ..., log ₂ N = K

In Formula 4, R ₀ (t) = 1.

After mapping "1" to "0" and mapping "-1" to "1", the Walsh code with 32-bit bit length generated by the Rademacher function is equivalent to the OVSF code shown in Equation 5. Able to know.

R ₁ = C _32,1 = 00000000000000001111111111111111

R ₂ = C _32,2 = 000000001111111 _{10000000011111111}

R ₃ = C _32,4 = _{00001111000011110000111100001111}

R ₄ = C _32,8 = 00110011001100110011001100110011

R ₅ = C _32,16 = 01010101010101010101010101010101

Here, the code having a 32-bit bit length generated by the Rademacher function and the code generated by the Hadamard function have a base inversion (= index conversion) relationship as shown in Equation 6 below.

R ₁ = H _32,16 , R ₂ = H _32,8 , R ₃ = H _32,4 , R ₄ = H _32,2 , R ₅ = H _32,1

Therefore, the OVSF code and the Hadamard code have a base inversion (= index conversion) relationship as shown in Equation 7 below.

As a result, in case of fast Hadamard transform decoding after the existing transport format information bit is encoded and transmitted, index conversion must be performed.

However, when the TFCI encoding is performed on a pre-barrel shifted bit pattern as in the proposed bit pattern of FIG. 6, the existing transmission format information bit pattern is input as it is, but instead is linearly combined with the input information bit. In the case of using the TFCI encoder of FIG. 7B which differs in the arrangement of the base sequences, the receiver does not need to perform index conversion.

The following describes the decoding procedure for the TFCI codeword at the receiving side using the above principle.

8 is a block diagram illustrating an optimal TFCI decoding procedure according to the present invention.

Referring to FIG. 8, the receiver cannot know whether the first bit and the seventeenth bit punctured the 32-bit codeword at the transmitting side were "1" or "0". Therefore, in the prior art, when depuncturing a 30-bit codeword received at the receiving side, a 32-bit codeword was created after decoding a bit by leaving a bit blank in the corresponding order.

However, if the hardware structure for TFCI transmission shown in FIG. 7 is used as in the present invention, when the number of bits of the transmitted transport format information bits is less than 6 bits, the codeword encoded and transmitted becomes Hadamard code. Error can be reduced.

Here are the characteristics of the Hadamard code:

First, when the number of bits of the input transport format information bit is 1 to 4 bits, the first bit and the 17th bit of the 32-bit TFCI codeword always have a bit value of "0".

Second, if the number of bits of the input transport format information bits is 5 bits, the first bit of the 32-bit TFCI codeword always has a bit value of "0".

Therefore, using the characteristics of the Hadamard code, the 30-bit codeword received at the receiving side of the present invention is depunctured.

In this case, since the receiving side knows the number of bits of the input transmission format information bits by the signal processing of the upper layer, it depunctures as in the following three cases.

First, when the number of bits of the input transport format information bit is 1 to 4 bits, the receiving side has the bit value of the first bit and the 17th bit having punctured the 32-bit codeword at the transmitting side as "0". It can be seen that " 0 " has been mapped and transmitted to " 1 ", so the receiving side fills in the " H " value for the first bit and the 17th bit. Here, "H" is any high bias value.

Second, when the number of bits of the input transport format information bit is 5 bits, the receiving side has a bit value of "0" of the first bit puncturing a 32-bit codeword at the transmitting side, and this bit value "0" is "1". Since the receiver is filled with "H" for this first bit, it knows whether the bit value of the 17th bit that punctured the 32-bit codeword was "1" or "0". Therefore, the receiving side fills in "B" for this 17th bit. "B" here means a bit blank.

Third, when the number of bits of the input transport format information bit is 6 bits or more, the receiving side knows whether the bit values of the first bit and the 17th bit that punctured the 32-bit codeword at the transmitting side were "1" or "0". The receiver fills in "B" for this first bit and the 17th bit since it cannot be.

The depuncturing block 10 on the receiving side performs depuncturing according to the number of bits of the transport format information bits input as described above.

The TFCI decoder 20 then decodes the 32-bit codeword by depuncturing as an input.

On the other hand, the receiving end receives the 30-bit codeword R (t) shown in the following expression (8).

R (t) = [R (2) R (3) ... R (16) R (18) ... R (31) R (32)]

Thereafter, the depuncturing block 10 performs depuncturing according to the number of bits of the input transport format information bit, and outputs a 32-bit codeword for each case (Case1, Case2, Case3) as shown in Equations 9 to 11 below. .

[H R (2) R (3) ... R (16) H R (18) ... R (31) R (32)]

[H R (2) R (3) ... R (16) B R (18) ... R (31) R (32)]

[B R (2) R (3) ... R (16) B R (18) ... R (31) R (32)]

Eventually, when the receiving end knows what the value of the punctured bit is, the receiving side substitutes the bit value into the corresponding bit position to generate a 32-bit codeword. The TFCI decoder 20 then decodes the 32-bit codeword as an input and restores the desired transmission format information bit.

As described above, by using the optimal TFCI transmission method according to the present invention, the receiving side can decode the encoded TFCI codeword by a simpler procedure.

That is, when the input transmission format information bit is less than 6 bits, the receiving side decodes by inserting a high bias value into the punctured bit position at the transmitting side, so that the encoded codeword can be accurately determined. A simpler procedure is used to decode coded codewords, and hardware implementation is simple.

Claims (4)

Shifting a predetermined number of bits of the transport format information bits and then performing corresponding coding determined according to the number of bits of the transport format information bits; Puncturing the codeword by the coding at a predetermined bit position, and inserting and inserting the codeword into each slot of the radio frame; Receiving the transmitted codeword, Depuncturing by inserting an arbitrary bit value at the punctured bit position in the received codeword; Decoding the depunctured codeword, restoring an original transmission format information bit. The method of claim 1, wherein after the puncturing, the binary bit value of the punctured codeword is converted into a bipolar bit value and then transmitted. 2. The method of claim 1, wherein when the transmission format information bit is less than a specific bit length, the bit string is barrel-shifted after a predetermined bit string is created by padding from the most significant bit by a bit short of the predetermined bit length. Optimal TFCI transmission method characterized by performing OVSF coding on a barrel-shifted bit stream. The method of claim 1, wherein the depuncturing step comprises: If the number of bits of the transport format information bits is less than 5 bits, a high-level bias value is assigned to the punctured bit position. If the number of bits of the transport format information bits is 5 bits, the punctured bit position is assigned to the punctured bit position. And assigning a high-level bias value and a bit blank and assigning a bit blank to each of the punctured bit positions when the number of bits of the transport format information bit exceeds 5 bits.