Method for physical control format indicator channel mapping
A method of mapping symbols of a physical control format indicator channel (PCFICH) is described. A start position of a resource element to map the symbols for the PCFICH is determined by flooring a value, obtained by multiplying the number of resource blocks by a variable proportional to a symbol index for the PCFICH and then dividing the multiplied result by 2, wherein the resource blocks are transmitted in downlink. The symbols are mapped in the start position. Therefore, a problem of wasting resource elements or not being able to implement mapping can be solved by applying a simple mapping rule while mapping symbols of the PCFICH.
1. In an orthogonal frequency division multiplexing (OFDM) wireless communication system, a method of mapping physical control format indicator channel (PCFICH) symbols to resource elements in one of a plurality of OFDM symbols associated with a downlink slot, the method comprising:
determining the position, K 0 , of a first one of the resource elements in the OFDM symbol; and
mapping each of the PCFICH symbols in groups of four to a corresponding set of four resource elements, in the OFDM symbol as a function of K 0 , N RB DL divided by two (N RB DL /2), and the N SC RB ,
wherein a first group of four PCFICH symbols is mapped to a first set of four resource elements in the OFDM symbol, where the first resource element of the first set of four resource elements is at the position K 0 , and
wherein a second group of four PCFICH symbols is mapped to a second set of four resource elements in the OFDM symbol, where the first resource element of the second set of four resource elements is at a position defined by K 0 +└N RB DL /2┘*N SC RB /2,
wherein K 0 is the position of a first one of the resource elements in the OFDM symbol, N RB DL is the number of resource blocks in downlink, and N SC RB is the number of resource elements per resource block in a frequency domain.
2. The method of claim 1 , wherein the position, K 0 , of the first resource element is based on a physical layer cell identifier, N ID cell .
3. The method of claim 1 , wherein
a third group of four PCFICH symbols is mapped to a third set of four resource elements in the OFDM symbol, where the first resource element of the third set of four resource elements is at a position defined by K 0 +└2N RB DL /2┘*N SC RB /2.
4. The method of claim 3 , wherein
a fourth group of four PCFICH symbols is mapped to a fourth set of four resource elements in the OFDM symbol, where the first resource element of the fourth set of four resource elements is at a position defined by K 0 +└3N RB DL /2┘*N SC RB /2.
5. The method of claim 1 , wherein the PCFICH is expressed as 2 bits, and wherein the value of the 2 bits define whether 1, 2 or 3 OFDM symbols in the downlink slot are used for transmitting a control channel.
6. The method of claim 5 further comprising:
increasing the 2 bits to 32 bits through channel coding.
7. The method of claim 6 further comprising:
modulating the 32 bits such that they are expressed as 16 quadrature phase shift keying (QPSK) symbols.
8. In an orthogonal frequency division multiplexing (OFDM) wireless communication system, a method of mapping physical control format indicator channel (PCFICH) symbols to resource elements in one of a plurality of OFDM symbols associated with a downlink slot, the method comprising:
determining K 0 , which is the position of a first one of the resource elements in the OFDM symbol, wherein K 0 is based on a physical layer cell identifier, N ID cell ;
mapping each of the PCFICH symbols in groups of four to a corresponding set of four resource elements in the OFDM symbol as a function of K 0 , N RB DL divided by two (N RB DL /2) and the N SC RB , wherein a first group of four PCFICH symbols is mapped to a first set of four resource elements in the OFDM symbol, where the first resource element of the first set of four resource elements is at the position K 0 , and wherein a second group of four PCFICH symbols is mapped to a second set of four resource elements in the OFDM symbol, where the first resource element of the second set of four resource elements is at a position defined by K 0 +└N RB DL /2┘*N SC RB /2; and
transmitting the PCFICH symbols,
wherein K 0 is the position of a first one of the resource elements in the OFDM symbol, N RB DL is the number of resource blocks in downlink, and N SC RB is the number of resource elements per resource block in a frequency domain.
9. The method of claim 8 , wherein mapping the PCFICH symbols in groups of four comprises:
mapping a third group of four PCFICH symbols to a third set of four resource elements in the OFDM symbol, where the first resource element of the third set of four resource elements is at a position defined by K 0 +└2N RB DL /2┘*N SC RB /2; and
mapping a fourth group of four PCFICH symbols to a fourth set of four resource elements in the OFDM symbol, where the first resource element of the fourth set of four resource elements is at a position defined by K 0 +└3N RB DL /2┘*N SC RB /2.
10. The method of claim 8 , wherein the PCFICH is expressed as 2 bits, and wherein the value of the 2 bits define whether 1, 2 or 3 OFDM symbols in the downlink subframe slot are used for transmitting a control channel.
11. The method of claim 10 further comprising:
increasing the 2 bits to 32 bits through channel coding.
12. The method of claim 11 further comprising:
modulating the 32 bits such that they are expressed as 16 quadrature phase shift keying (QPSK) symbols.