Pilot pattern design for a STTD scheme in an OFDM system
View Patent ↗The present invention relates to a transmitting device and a receiving device in a wireless orthogonal frequency division multiplex (OFDM) communication system with space time transmit diversity (STTD). Further, the present invention relates to a channel estimation method for performing a channel estimation in such a wireless communication system, in which the transmitting device comprises a first and a second antenna for transmitting signals with space time transmit diversity. The first and the second antenna means are arranged spaced apart from each other in a space diversity arrangement, whereby first and second pilot symbols are transmitted via said first and said second antenna means, respectively. Some of the second pilot symbols are orthogonal to corresponding ones of the first pilot symbols, so that a channel estimation to separately determine the transmission quality of signals transmitted from the first and the second antenna means, respectively, can be performed in a receiving device which receives the signals with only one single antenna.
1. A transmitting device for transmitting signals in a wireless orthogonal frequency division multiplex (OFDM) communication system with multiple transmission antennas, comprising:
first and a second antenna means for transmitting data of a first and a second data stream, respectively, in OFDM signals; and
pilot symbol generating means for generating first and second pilot symbols to be transmitted among said data of said first and second data stream, wherein said first pilot symbols are transmitted via said first antenna and said second pilot symbols are transmitted via said second antenna,
wherein said first and said second pilot symbols correspond to one another and have the same frequency and time allocation and a regular distribution in the time and frequency dimension in the OFDM system,
and wherein at least some pairs of said first pilot symbols adjacent in the frequency dimension are respectively orthogonal to corresponding pairs of said second pilot symbols and at least some pairs of said first pilot symbols adjacent in the time dimension are respectively orthogonal to the corresponding pairs of said second pilot symbols.
2. A transmitting device according to claim 1 ,
wherein corresponding ones of said first and second pilot symbols having the same frequency and time allocation are alternatingly identical and orthogonal to each other in the frequency and time dimension.
3. A receiving device for receiving signals in a wireless orthogonal frequency division multiplex (OFDM) communication system with multiple transmission antennas, comprising:
a single antenna means for receiving signals transmitted from a first and a second antenna means of a transmitting device of the OFDM communication system, said first and said second antenna means transmitting corresponding first and second pilot symbols respectively,
wherein said first and said second pilot symbols correspond to one another and have the same frequency and time allocation and a regular distribution in the time and frequency dimension in the OFDM system, and wherein at least some pairs of said first pilot symbols adjacent in the frequency dimension are respectively orthogonal to the corresponding pairs of said second pilot symbols and at least some pairs of said first pilot symbols adjacent in the time dimension are respectively orthogonal to the corresponding pairs of said second pilot symbols; and
processing means for detecting pilot symbols in the received signals, for processing detected pilot symbols and performing a channel estimation on the basis of said processing to separately determine the transmission quality of signals transmitted from each of said first and said second antenna means.
4. A receiving device according to claim 3 ,
wherein said first and second pilot symbols transmitted from said first and second antenna means are alternatingly identical and orthogonal to each other in the frequency and time dimension, and adjacent pairs of said pilot symbols are processed to determine the transmission quality.
5. A channel estimation method for performing a channel estimation in a wireless orthogonal frequency division multiplex (OFDM) communication system in which a transmitting device comprising a first and a second antenna transmits signals, comprising the steps of:
transmitting first and second pilot symbols via said first and said second antenna means, respectively, wherein said first and said second pilot symbols correspond to one another and have the same frequency and time allocation and a regular distribution in the time and frequency dimension in the OFDM communication system,
and wherein at least some pairs said of first pilot symbols adjacent in the frequency dimension are respectively orthogonal to corresponding pairs of said second pilot symbols and at least some pairs of said first pilot symbols adjacent in the time dimension are respectively orthogonal to the corresponding pairs of said second pilot symbols;
receiving said pilot symbols in a single antenna of a receiving device; and
processing said received pilot symbols and performing a channel estimation on the basis of said processing to separately determine the transmission quality of said signals transmitted from said first and said second antenna means.
6. A channel estimation method according to claim 5 ,
wherein said first and second pilot symbols transmitted from said first and second antenna means are alternatingly identical and orthogonal to each other in the frequency and time dimension, and adjacent pairs of pilot symbols are processed to determine the transmission quality.