CN100364236C - Space hour coding method and corresponeded transmitting method, transmitter and communication system - Google Patents
Space hour coding method and corresponeded transmitting method, transmitter and communication system Download PDFInfo
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Abstract
The present invention discloses a novel space-time coding method and the application thereof under the conditions of space diversity and time diversity. The space-time coding method comprises the coding procedures: an N*N dimensional coding generator matrix is adopted to linearly transform each group of data blocks, and the coding generator matrix has the structure that the first column elements choose arbitrary nonzero values; the (n+1)th column elements are obtained by arbitrarily rotating the corresponding elements of the nth column at the phase position under the condition that the obtained code symbols are not zero; every element symbol in each column is completely identical, or the symbols between columns are orthogonal. When the space diversity is in application, a plurality of antennas are arranged at a transmitting terminal, initial data are transmitted in sequence on the antennas after the course of space-time coding, and a receiving terminal can achieve the effect of diversity by using only one antenna. When time diversity is in application, the performance of an STBC system using a plurality of antennas can be achieved without additionally increasing antennas, and the performance is superior to that of the STBC system when the amount of the adopted antennas is identical to that of the STBC system.
Description
The technical field is as follows:
the invention belongs to the technical field of mobile communication systems, and particularly relates to a space-time coding method, a corresponding transmitting method, a corresponding transmitter and a corresponding communication system for the space-time coding method under the conditions of space diversity and time diversity.
Background art:
the development of modern communications requires mobile communication systems to be able to provide higher and higher data transmission rates. However, in a wireless communication system, a mobile channel through which a transmission signal passes from a transmitting end to a receiving end may experience severe fading due to the influence of a multipath environment. Space-time coding is an effective means to overcome the impact of this deficiency of the radio channel on the quality of the transmitted signal: STTC (space-time trellis coding) can provide the maximum possible diversity gain and coding gain without sacrificing transmission bandwidth efficiency, but the decoding of such codes is too complex to be implemented; STBC (space-time block coding) decoding, although simpler, is premised on the assumption of slow channel fading.
STBC assumes that the channels experienced by several information symbols are identical, with the input being a series of modulated symbols. The encoder encodes a group of symbols, and the resulting codeword is arranged in the form of a matrix having a number of rows equal to the number of transmit antennas and a number of columns equal to the number of time slots experienced by the sequence of symbols. The receiving end performs decoding using the maximum likelihood criterion, and the orthogonal structure of the codeword simplifies the decoding process. STBC can achieve maximum code rate 1 for any real signal. However, for complex signals, the code rate of STBC can only reach 1 if the number of transmit antennas is 2; when the number of transmitting antennas is 3 and 4, complex signalsWith transmission rate up to maximum code rate for STBC
(ii) a If the number of transmitting antennas continues to increase, the transmission rate of the coding mode is reduced to the maximum code rate
In addition, if the terminal moves at a high speed, fast fading of the channel experienced by the signal occurs. At this point, STBC will no longer be applicable. Currently, diversity techniques are mainly used to compensate for the signal loss caused by channel fading.
The invention content is as follows:
the invention provides a novel space-time coding method and a corresponding transmitting method, a transmitter and a communication system thereof under the conditions of space diversity and time diversity aiming at the inherent defects of a wireless channel.
A first object of the present invention is to provide a novel space-time coding method that can achieve both diversity gain and maximum transmission rate.
A second object of the present invention is to provide a transmitting method and a corresponding transmitter apparatus for spatial diversity.
A third object of the present invention is to provide a transmitting method and a corresponding transmitter apparatus applied to the time diversity condition.
A fourth object of the present invention is to provide a communication system using the above coding method and transmitter apparatus thereof.
The technical scheme of the invention is as follows:
a space-time coding method comprises the following steps:
1. a modulation step: according to the required modulation mode, carrying out digital modulation on the binary information data stream, namely modulating the binary information data into symbols;
2. a data grouping step: dividing the modulated data into a plurality of data blocks with N symbols as a group, wherein N is an integer greater than 1;
3. and (3) encoding: and carrying out linear transformation on each grouped data block by using the coding generating matrix to form a coded data block with one group of N symbols. The coding generator matrix used is not the coding mode in STTC or STBC, but is a matrix with dimension of NxN, and the structure is as follows: column 1 elements may take any non-zero value; the N +1 th column element can be rotated in phase by an arbitrary angle from the corresponding element in the nth column (N =1,2, …, N-1) with the guarantee that the resulting code symbol is not 0. Each element of each column is completely the same or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of input data before coding.
The present invention applies the space-time coding method described above to the following two cases:
one, slow fading channel
When the channel environment experienced by the signal is slow fading, i.e. the channel environment is the same as the channel environment assumed in STBC, the coding of the present invention employs a transmission method suitable for spatial diversity: and sequentially transmitting the N symbols of each group after coding in N symbol intervals by using N antennas, namely, sequentially transmitting the coded symbols on each transmitting antenna in turn. The corresponding transmitter arrangement comprises:
1. a modulation device: and the modulation module is used for modulating the original binary bit information into symbols according to a required modulation mode.
2. A data grouping device: for dividing the modulated data into a group of several data blocks with N symbols, N being an integer greater than 1.
3. An encoding device: and the encoding generator is used for carrying out linear transformation on each grouped data block by using the encoding generating matrix to form an encoded data block with a group of N symbols. The coding generation matrix used is not the coding mode in STTC or STBC, but is an N multiplied by N dimensional matrix, and the structure is as follows: column 1 elements may take any non-zero value; the N +1 th column element can be rotated in phase by an arbitrary angle from the corresponding element in the nth column (N =1,2, …, N-1) with the guarantee that the resulting code symbol is not 0. Each element of each column is completely the same or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of input data before coding.
4. The transmitting device: for transmitting the N symbols in each encoded group of data blocks into the channel in sequence over N antennas.
Fast fading channel
When the channel environment experienced by the signal is fast fading, the coding of the present invention adopts a transmission method suitable for time diversity: after the coded data is interleaved according to the required depth through the interleaving step, the interleaved coded symbols are continuously transmitted in different time by using an antenna through the transmitting step. The corresponding transmitter arrangement comprises:
1. a modulation device: and the modulation method is used for modulating the original binary bit information into symbols according to a required modulation mode.
2. A data grouping device: for dividing the modulated data into a group of several data blocks with N symbols, N being an integer greater than 1.
3. An encoding device: and the encoding generator is used for carrying out linear transformation on each grouped data block by using the encoding generator matrix to form an encoded data block with one group of N symbols. The coding generation matrix used is not the coding mode in STTC or STBC, but is an N multiplied by N dimensional matrix, and the structure is as follows: column 1 elements may take any non-zero value; the N +1 th column element can be rotated in phase by an arbitrary angle from the corresponding element in the nth column (N =1,2, …, N-1) with the guarantee that the resulting code symbol is not 0. Each element of each column is completely the same or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of input data before coding.
4. An interleaving device: for interleaving the encoded data, the interleaving depth should be no less than the correlation time of the fast fading channel, so as to ensure that the channels experienced by the adjacent N encoded symbols are low correlation.
5. The transmitting device: for transmitting the N symbols of each encoded group of data blocks into the channel successively at different times from the same antenna.
Further, a communication system of the present invention comprises the above transmitter apparatus, and a receiver comprising channel estimation and applying a maximum likelihood criterion for signal detection.
The space-time coding method of the invention is a space-time coding mode which can obtain diversity gain and improve transmission rate. The invention is characterized in that firstly, the modulated information data stream is divided into blocks, and then each data block is subjected to linear transformation by using a coding generation matrix to obtain a coding symbol. The coding generation matrix used is not the coding mode in STTC or STBC, but is an N multiplied by N dimensional matrix, and the structure is as follows: column 1 elements may take any non-zero value; the N +1 th column element can be rotated in phase by any angle from the corresponding element in the nth column (N =1,2, …, N-1) with the guarantee that the resulting code symbol is not 0; each element of each column is identical, or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of input data before coding. If the channel experienced by the signal is slow fading, the coded symbols are transmitted sequentially in a plurality of symbol intervals using a plurality of antennas: if the channel experienced by the signal is fast fading, the coded symbols are interleaved and transmitted continuously with one antenna at different times. Gains in spatial diversity or time diversity can be achieved after processing the signals on the receive antennas, as long as the channels experienced by the individual coded symbols in each group are guaranteed to be low correlated.
The invention has the advantages and positive effects that:
1. when the space diversity is used, the invention arranges a plurality of antennas on the transmitting end, carries out space-time coding on the original information data, and then alternately and sequentially transmits the coded symbols on the plurality of antennas, and the receiving end only uses one antenna for receiving to achieve the effect of the diversity. When the scheme is applied to the downlink, the overhead of the mobile terminal is obviously reduced; meanwhile, the error rate, the transmission rate and the system capacity of the system are improved to a certain extent.
2. When time diversity is used, the invention does not require increasing the number of transmitting antennas or receiving antennas, which reduces the requirement on the complexity of system equipment, but can still achieve the performance of the STBC system using a larger number of antennas; when the number of antennas used by the system adopting the invention is the same as that of the STBC system, the performance of the system is obviously better than that of the STBC system.
3. The present invention can be directly applied to a transmitter in an existing mobile communication system as long as a device for adding a data packet at a transmitting end and an encoder for encoding using the encoding generator matrix of the present invention.
4. The receiving device in the communication system of the present invention can be compatible with a receiving device of MIMO.
Description of the drawings:
FIG. 1: the invention adopts the structure block diagram of the transmitting terminal when the space diversity is adopted
FIG. 2: when the invention adopts space diversity, the system model block diagram with the number of transmitting antennas being 2 and the number of receiving antennas being 1
FIG. 3: when the invention adopts space diversity, the system model block diagram with N transmitting antennas and 1 receiving antennas
FIG. 4: the invention adopts the structure block diagram of the transmitting terminal when the time diversity is adopted
FIG. 5: when the invention adopts space diversity, 2 symbols are coded in one group, the comparison of the STBC system (2 transmitting antennas and 1 receiving antenna) and the diversity-free system (1 transmitting antenna and 1 receiving antenna) with the same transmission rate of the simulation bit error rate curve of the system with 2 transmitting antennas and 1 receiving antennas
FIG. 6: when the invention adopts time diversity, 2 symbols are coded as a group, the simulation bit error rate curve of the system with the number of transmitting antennas of 1 and the number of receiving antennas of 1 is compared with the STBC system (2 transmitting antennas i receiving antennas) and the diversity-free system (1 transmitting antenna 1 receiving antenna) with the same transmission rate
FIG. 7 is a schematic view of: when the invention adopts time diversity, 2 symbols are coded as a group, the simulation bit error rate curve of the system with the number of transmitting antennas of 1 and the number of receiving antennas of 2 is compared with the STBC system (2 transmitting antennas and 1 receiving antennas) with the same transmission rate and the same number of applied antennas
The specific implementation mode is as follows:
when the channel experienced by the signal is slow fading, namely the correlation time of the channel is long, the system adopts space diversity, and a plurality of antennas sequentially transmit coded symbols in different symbol intervals; when the channel experienced by the signal is fast fading, i.e. the correlation time of the channel is short, the system uses time diversity to continuously transmit the interleaved code symbols from the same antenna at different times.
The principles of this patent are described below by way of specific examples and mathematical expressions thereof:
1. space diversity
First, a communication system structure when the spatial diversity is employed in the present invention will be described with reference to fig. 1.
The number of the antennas at the transmitting end of the system is N, and the number of the antennas at the receiving end is 1. And only one transmitting antenna is used for transmitting one coded symbol in one symbol interval, and N transmitting antennas sequentially transmit N coded symbols in the coded group of data in N symbol intervals.
Data chunking
And grouping the modulated information data stream, wherein N symbols form a data block. Without loss of generality, the t-th data block after grouping can be represented in a vector form as
S t ＝[S t1 ，S t2 ，…，S tN ] T ，t＝1，2，… (1)
Structure of (II) code
Selecting an NxN-dimensional matrix as the code generating matrix, i.e.
The matrix is characterized in that: column 1 elements may take any non-zero value; the N +1 th column element can be rotated in phase by an arbitrary angle from the corresponding element in the nth column (N =1,2, …, N-1) with the guarantee that the resulting code symbol is not 0. Each element of the columns is identical or the columns are orthogonal.
The t-th group of data after coding is
X t ＝GS t (3)
Namely, it is
Wherein, X 1 ＝[X t1 ，X t2 ，…，X tN ] T T =1,2, …, and
(k =1,2, …, N), that is, each encoded symbol obtained after encoding of each group of data is a linear combination of all N symbols in the group of data input before encoding.
To obtain diversity gain, it must be ensured that the transmitted energy in the channel is not 0, i.e. for any t =1,2, …, k =1,2, …, N, there is a constant value for
X tk ≠0 (5)
(III) data Transmission
Each group of data X after being coded t Transmitted in N symbol intervals. N of the N symbol intervalsThe transmitting antennas alternate and sequentially transmit the coded t-th group of data X t ＝[X t1 ，X t2 ，…，X tN ] T (t =1,2, …) each symbol in the X-ray transmission with one antenna in each symbol interval t One data X in (2) tk K =1,2, …, N. That is, in the kth symbol interval of the t group of data, the symbol X is transmitted by the kth antenna tk (ii) a Transmitting symbol X by using the (k + 1) th antenna in the (k + 1) th symbol interval of the t-th group data t(k+1) (ii) a And so on; and for the t +1 th group of data, the N transmitting antennas are used for rotating transmission again.
A transmitter apparatus applied to a spatial diversity system is explained with reference to fig. 1. The transmitter apparatus includes:
1. a modulation device: the method is used for modulating original binary bit information into a symbol according to a required modulation mode;
2. a data grouping device: the data processing device is used for dividing the modulated data into a group of data blocks with N symbols, wherein N is an integer greater than 1;
3. an encoding device: the system comprises a coding generator matrix, a data block generator matrix and a data block decoder matrix, wherein the coding generator matrix is used for carrying out linear transformation on each grouped data block to form a coded data block with a group of N symbols, and the coding generator matrix is an N multiplied by N dimensional matrix (2) introduced above;
4. the transmitting device: for transmitting the encoded groups of data into the channel in N symbol intervals from the N antennas in sequence;
the corresponding receiving device: after estimating the channel, the receiving end detects the signal by adopting the maximum likelihood criterion.
A preferred embodiment of the invention when employing spatial diversity is described below with reference to fig. 2: a system with 2 transmit antennas (i.e., N = 2).
1. Signal encoding
The system adopts BPSK modulation, i.e. each symbol carries 1bit of information.
First, the information data stream is grouped, and 2 symbols constitute one data block. Without loss of generality, we take the processing of one set of signals as an example. It is assumed that any set of data symbols can be represented as a vector s = [ s ] 1 ，s 2 ] T Wherein s is 1 ，s 2 ∈{1，-1}。
The coding used by us generates a matrix of
Wherein,
。G 2 representing a 2 x 2 dimensional code generator matrix.
After encoding, the group of data is
x＝G 2 s (7)
Namely, it is
Wherein, x = [ x ] 1 ，x 2 ] T 。
2. Signal transmission
The coded symbols transmitted by the two antennas of the transmitting end in two symbol intervals are shown in table 1:
| 1 st racket | 2 nd racket | |
| Transmitting antenna 1 | x 1 | 0 |
| Transmitting antenna 2 | 0 | x 2 |
TABLE 1 coded symbols transmitted by two transmit antennas in two symbol intervals
3. Signal reception
As shown in FIG. 2, the received signal of beat 1 is
y 1 ＝h 1 x 1 +n 1 ＝h 1 (s 1 +is 2 )+n 1 (9)
The received signal of the 2 nd beat is
y 2 ＝h 2 x 2 +n 2 ＝h 2 (s 1 -is 2 )+n 2 (10)
h 1 Denotes the channel parameter, h, from transmit antenna 1 to receive antenna in beat 1 2 Which represent the channel parameters from transmit antenna 2 to the receive antenna in beat 2, are independent of each other. n is 1 And n 2 The noise encountered by the signal in two beats on the receiving antenna is independent and identically distributed complex Gaussian random variables, namely, the mean value of the real part and the imaginary part is 0, and the variance is sigma 2 A gaussian random variable of/2.
Taking into account the noise n in two beats 1 And n 2 The receiving end adopts the maximum likelihood criterionAnd judging the received signal. Assuming that the estimation of the channel parameters is completely correct, then, if for any m ≠ n, p ≠ q,exist and exist exclusively
d 2 (y 1 ，h 1 (s 1m +is 2p ))+d 2 (y 2 ，h 2 (s 1m -is 2p ))
(11)
≤d 2 (y 1 ，h 1 (s 1n +is 2q ))+d 2 (y 2 ，h 2 (s 1n -is 2q ) In time), signal is selected 1 ＝s 1m And 2 ＝s 2p As an estimate of the original information data. Wherein d is 2 (a, b) represents the squared Euclidean distance between signals a and b, and s 1m ，s 1n ，s 2p ，s 2q Traverse s 1 ，s 2 E {1, -1}, and s 1m ≠s 1n ，s 2p ≠s 2q 。
The coding method, the transmitting method and the communication system for two transmitting antennas can be easily extended to the case of transmitting by N antennas and adopting other modulation modes by the system. A system block diagram is shown in fig. 3.
The general form of the encoding generator matrix employed is
(12) The equation gives the optimal matrix form, where,
。G N the code representing the N × N dimensions generates a matrix: the elements in column 1 are all 1, and the elements in column n +1 are phase rotations of the corresponding elements in column n
Obtained after (N =1,2, …, N-1). (12) The elements given in the formula matrix do not relate to the sign of the element: the elements of each column may be identical (in the form of equation (12)), or the columns may be orthogonal to each other. The modulus of each element is 1, so that the transmitting power of the system is not increased; the rotation angles among the columns are uniformly and progressively increased, namely the intervals of the rotation angles among the columns are the same, so that the distance between each corresponding point of the information symbol in the constellation diagram is the largest, the influence of Gaussian white noise in a channel on the whole system is ensured to be the smallest, and the obtained effect is the best.
Each group of symbols after grouping is encoded by the formula (12), as shown in formula (3), i.e.
Wherein, X t ＝[X t1 ，X t2 ，…，X tN ] T ，t＝1，2，…。
2. Time diversity
If the terminal moves at a high speed, the wireless channel experienced by the signal becomes a fast fading channel, and the correlation time is short. In this case, time diversity can be used after interleaving the coded symbols, and the interleaving depth does not need to be large to ensure that the channels through which the coded symbols in each set of data are transmitted are low correlated.
The system structure when the time diversity is employed in the present invention will be described with reference to fig. 4.
The system transmits N interleaved coded symbols in successive N symbol intervals using only one transmit antenna.
Data partitioning and encoding
The modulated information symbol stream is first divided into data blocks and then encoded. The data grouping method and the coding structure are the same as those described in the space diversity section.
(II) data interleaving
The coded data X 1 ，X 2 ，…，X t …, it is necessary to guarantee that any set of data X after interleaving t The channels through which each encoded symbol in (t =1,2, …) passes are low correlated. That is, if the interleaving depth is M symbols and the time interval of each symbol is T, the MT should be no less than the correlation time of the fast fading channel when the terminal moves at a high speed.
(III) Signal Transmission
The interleaved encoded symbols are transmitted successively into the channel using the same transmit antenna at different times.
(IV) Signal reception
We do not consider the channel estimation part, so we assume that the parameters of the channel gain are known.
The receiving end may use one antenna or multiple antennas.
1. Case of using one antenna at receiving end
After deinterleaving the data on the receiving antennas, the obtained t-th group of data can be represented as a vector
Y t ＝[Y t1 ，Y t2 ，…，Y tN ] (14)
Wherein,
Y tj ＝h tj X tj +n tj ，j＝1，2，…，N
h tj is the channel parameter, n, traversed by the signal in the jth symbol interval in the t group tj Is the gaussian noise on the receive antenna in the jth symbol interval in the tth group.
By substituting the formula (4) into the formula (14), the compound
The above equation is the same as the MIMO format. The receiving apparatus of the present invention can be compatible with a receiving apparatus of MIMO.
2. Case of using two antennas at the receiving end
After the data on the two receiving antennas are de-interleaved, the obtained t-th group of data can be respectively expressed as vector
Wherein,
h tj (k) is the channel parameter n passed by the signal from the transmitting antenna to the kth receiving antenna in the jth symbol interval in the t group tj (k) Is the gaussian noise on the receive antenna k in the jth symbol interval in the t-th group.
By substituting the formula (4) into the formulae (16) and (17), the compounds can be obtained
Therefore, the method can be easily popularized to the condition that a plurality of antennas are used at a receiving end. The more the number of the receiving end antennas is, the larger the receiving diversity gain obtained by the system is.
A transmitter apparatus applied to the time diversity system is explained with reference to fig. 4. The transmitter apparatus includes:
(1) A modulation device: the modulation method is used for modulating original binary bit information into symbols according to a required modulation mode;
(2) A data grouping device: the data processing device is used for dividing the modulated data into a group of a plurality of data blocks with N symbols, wherein N is an integer larger than 1;
(3) An encoding device: the system comprises a code generator matrix, a matrix generator and a decoder, wherein the code generator matrix is used for carrying out linear transformation on each grouped data block to form a coded data block with a group of N symbols, and the code generator matrix is an N multiplied by N dimensional matrix (2) introduced by the space diversity part;
(4) An interleaving device: for interleaving encoded data, characterized in that the interleaving depth should not be less than the correlation time of a fast fading channel, thereby ensuring that the channel experienced by adjacent N symbol encoding is low correlation.
(5) The transmitting device: for transmitting interleaved encoded data from the same antenna into the channel sequentially at different times.
The corresponding receiving device: after estimating the channel, the receiving end detects the signal by adopting the maximum likelihood criterion.
Two preferred embodiments of the invention employing time diversity are described below with reference to fig. 4: a system where two symbols are coded in one group (i.e., N = 2), the number of transmit antennas is 1, and the number of receive antennas is 1 and 2, respectively.
System with 1 number of (one) receiving antennas
I. Signal transmission
The system employs BPSK modulation.
Firstly, the modulated information symbol stream is processed by block division, and two symbols are combined into a data block. The signal is encoded in the same way as in the previously described preferred embodiment of spatial diversity, and the selected code generator matrix is equation (6).
Without loss of generality, we assume that one set of encoded data is
After interleaving, x 1 And x 2 The channels traversed are low correlated.
Receiving signals
After de-interleaving at the receiving end, the resulting received signal can be expressed as
Signal detection
After channel estimation, the deinterleaved received signal is detected by the maximum likelihood criterion introduced in the preferred embodiment of space diversity, as shown in equation (11), to obtain the original information data s 1 And s 2 An estimate of (2).
(II) System with 2 receiving antennas
I. Signal transmission
The system employs BPSK modulation.
The processing of the signal at the transmitting end is the same as that of a system with 1 number of receiving antennas.
Receiving signals
After deinterleaving, the resulting signal at each receive antenna can be represented as
k＝1，2 (21)
Signal detection
After channel estimation, the signal in equation (21) is decided by the maximum likelihood criterion. Similar to the maximum likelihood criterion introduced in the preferred embodiment of spatial diversity (i.e., equation (11)), assuming that the estimate of the channel parameter is completely correct, then if for any m ≠ n, p ≠ q, there is and only exists
Then signal is selected 1 ＝s 1m And 2 ＝s 2p As an estimate of the original transmitted signal. Wherein d is 2 (a, b) represents the square of the Euclidean distance between signals a and b, and s 1m ，s 1n ，s 2p ，s 2q Traverse s 1 ，s 2 E {1, -1}, and s 1m ≠s 1n ，s 2p ≠s 2q 。
3. System emulation
Simulation conditions
The present invention employs Matlab programming to perform simulations of several preferred embodiments of the present invention introduced above under windows xp. The main simulation object is the relationship between the signal-to-noise ratio and the bit error rate.
The channel used in the model is a rayleigh flat fading channel.
In the preferred embodiment of space diversity, each channel parameter is assumed to be independently and equally distributed and is a complex Gaussian random variable with zero mean and unit variance
h j The mode of (a) is a random variable subject to a rayleigh distribution. Wherein, normal (0,1/) represents a Normal distribution with a mean value of 0 and a variance of 1/. h is j Represents the channel parameters from transmit antenna j to receive antenna in the jth symbol interval of each group of data, j =1,2.| h j | 2 Is obedience x 2 2 A random variable of distribution, and | h j | 2 Average value E | h of j | 2 And =1, ensuring that the received signal power is the same as the signal power at the time of transmission.
In the preferred embodiment of time diversity, each channel parameter is also assumed to be independently and identically distributed and is a complex Gaussian random variable with zero mean and unit variance
h jk The mode of (a) is a random variable subject to a rayleigh distribution. Wherein, normal (0,1/) represents a Normal distribution with a mean value of 0 and a variance of 1/. h is a total of jk The channel parameters from the transmit antenna to the receive antenna k in the j (j =1,2) th symbol interval of each group of data are represented (k =1 when the number of receive antennas is 1; k =1,2 when the number of receive antennas is 2). | h j | 2 Is obedience x 2 2 A random variable of distribution, and | h j | 2 Average value E | h of j | 2 And =1, ensuring that the received signal power is the same as the signal power at the time of transmission.
We do not consider this part of the channel estimation, so we assume that the receiving end can get the complete channel information.
(II) simulation results
Fig. 5 shows the comparison between the simulated bit error rate curve of the system with 2 transmitting antennas and 1 receiving antennas and the STBC system and the non-diversity system when the space diversity is adopted in the present invention, wherein 2 symbols are coded in one group. The transmission rates of the three are the same, and the maximum transmission rate can be achieved. The total number of antennas applied by the space diversity system and the STBC system adopting the invention is the same, except that the system adopting the invention can be used for the condition of channel slow fading and the condition of channel fast fading, and the STBC system can only be used for the condition of channel slow fading. It can be seen from the figure that the performance of the space diversity system adopting the invention is equivalent to that of the STBC system, and is greatly improved compared with that of the non-diversity system.
Fig. 6 shows the comparison of the simulated bit error rate curve of the system with 1 number of transmitting antennas and 1 number of receiving antennas with STBC system and non-diversity system, which uses time diversity, and 2 symbols are coded in one group. The transmission rates of the three are the same, and the maximum transmission rate can be achieved. The total number of antennas used by the time diversity system adopting the invention is less than that of antennas used by the STBC system: the number of the transmitting antennas and the receiving antennas of the time diversity system adopting the invention is 1, while the number of the transmitting antennas of the STBC system is 2 and the number of the receiving antennas is 1. The time diversity system adopting the invention is suitable for the condition of fast fading of the channel, and the STBC system is suitable for the condition of slow fading of the channel. It can be seen from the figure that when the channel is fast fading, the time diversity system using the present invention can achieve the same performance as the STBC system when the channel is slow fading, and all of them are greatly improved compared with the performance of the non-diversity system.
Fig. 7 shows a comparison of the simulated bit error rate curve of the system with time diversity, 2 symbols for a group for coding, 1 number of transmit antennas and 2 number of receive antennas, with the STBC system. The transmission rates of the two are the same, and the maximum transmission rate can be achieved. The total number of antennas used by both is also the same: the number of transmitting antennas of the time diversity system is 1, and the number of receiving antennas is 2; the number of transmitting antennas of the STBC system is 2, and the number of receiving antennas is 1. It can be seen from the figure that the time diversity system applying the present invention has a great improvement in performance over the STBC system when the channel is fast fading, compared to when the channel is slow fading.
While the principles and implementations of this invention have been described in detail above and with reference to preferred embodiments thereof, various modifications can be made by those skilled in the art without departing from the scope of the invention. For example, other methods are possible for selecting and changing the code generator matrix, the modulation scheme of the system, and the signal detection at the time of reception. Such modifications and variations do not depart from the scope of the invention.
Claims (11)
1. A space-time coding method, characterized by comprising the steps of:
(1) A modulation step: according to the required modulation mode, carrying out digital modulation on the binary information data stream, and modulating the binary information data into symbols;
(2) A data grouping step: dividing the modulated data into a plurality of data blocks which take N symbols as a group, wherein N is an integer larger than 1;
(3) And (3) encoding: carrying out linear transformation on each grouped data block by using a coding generation matrix to form a coded data block with N symbols as a group; the encoding generating matrix is an N multiplied by N dimensional matrix, and the structure is as follows: column 1 elements take any non-zero value; the N +1 th column element is rotated in phase by an arbitrary angle from the corresponding element of the N-th column with the guarantee that the resulting code symbol is not 0 (N =1,2, …, N-1); each element of each column is completely the same, or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of input data before coding.
2. A space-time coding method according to claim 1, wherein in the coding generated matrix in the coding step, the absolute value of the first column of elements is 1, and the N +1 th column of elements is obtained by rotating the corresponding element in the nth column by pi/N in phase (N =1,2, …, N-1).
3. A transmission method applied to spatial diversity, comprising the steps of:
(1) A modulation step: according to the required modulation mode, carrying out digital modulation on the binary information data stream, and modulating the binary information data into symbols;
(2) A data grouping step: dividing the modulated data into a plurality of data blocks which take N symbols as a group, wherein N is an integer larger than 1;
(3) And (3) encoding: carrying out linear transformation on each grouped data block by using a coding generation matrix to form a coded data block with N symbols as a group; the encoding generating matrix is an N multiplied by N dimensional matrix, and the structure is as follows: column 1 elements take any non-zero value; the N +1 th column element is rotated in phase by an arbitrary angle from the corresponding element of the N-th column with the guarantee that the resulting code symbol is not 0 (N =1,2, …, N-1); each element of each column is completely the same, or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of data input before coding;
(4) A transmitting step: the N coded symbols of each group after coding are transmitted in N symbol intervals in turn using N antennas.
4. The transmission method applied to spatial diversity according to claim 3, wherein in the encoding step generates a matrix in which the absolute value of the first column element is 1, and the N +1 th column element is obtained by rotating the corresponding element of the nth column by pi/N in phase (N =1,2, …, N-1).
5. A transmitter for spatial diversity, comprising means for:
(1) A modulation device: the modulation method is used for modulating original binary bit information into symbols according to a required modulation mode;
(2) A data grouping device: the data processing device is used for dividing the modulated data into a group of data blocks with N symbols, wherein N is an integer greater than 1;
(3) An encoding device: the linear transformation is carried out on each grouped data block by adopting a coding generating matrix to form a coding data block with N symbols as a group; the encoding generating matrix is an N multiplied by N dimensional matrix, and the structure of the encoding generating matrix is as follows: column 1 elements take any non-zero value; the N +1 th column element is rotated in phase by an arbitrary angle from the corresponding element of the N-th column with the guarantee that the resulting code symbol is not 0 (N =1,2, …, N-1); each element of each column is completely the same or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of data input before coding;
(4) The transmitting device: for transmitting the N symbols of each encoded group of data blocks from the N antennas into the channel in sequence in N symbol intervals.
6. The transmitter for spatial diversity according to claim 5, wherein in the encoding means generates a matrix in which the absolute value of the elements of the first column is 1 and the elements of the N +1 th column are obtained by rotating the corresponding elements of the N-th column by pi/N in phase (N =1,2, …, N-1).
7. A transmission method applied to time diversity, comprising the steps of:
(1) A modulation step: according to the required modulation mode, carrying out digital modulation on the binary information data stream, and modulating the binary information data into symbols;
(2) A data grouping step: dividing the modulated data into a plurality of data blocks which take N symbols as a group, wherein N is an integer larger than 1;
(3) And (3) encoding: carrying out linear transformation on each grouped data block by using a coding generation matrix to form a coded data block with N symbols as a group; the encoding generating matrix is an N multiplied by N dimensional matrix, and the structure is as follows: column 1 elements take any non-zero value; the N +1 th column element is rotated in phase by an arbitrary angle from the corresponding element of the N-th column with the guarantee that the resulting code symbol is not 0 (N =1,2, …, N-1); each element of each column is completely the same, or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of data input before coding;
(4) An interweaving step: interweaving the coded data according to the required depth;
(5) A transmitting step: the interleaved encoded symbols are transmitted successively over different times using one antenna.
8. The transmission method applied to time diversity as claimed in claim 7, wherein the encoding in the encoding step generates a matrix in which the absolute value of the elements in the first column is 1 and the elements in the N +1 th column are obtained by rotating the corresponding elements in the N-th column by pi/N in phase (N =1,2, …, N-1).
9. A transmitter for time diversity, comprising means for:
(1) A modulation device: the modulation method is used for modulating original binary bit information into symbols according to a required modulation mode;
(2) A data grouping device: the data processing device is used for dividing the modulated data into a group of data blocks with N symbols, wherein N is an integer greater than 1;
(3) An encoding device: the linear transformation is carried out on each grouped data block by adopting a coding generating matrix to form a coding data block with N symbols as a group; the encoding generating matrix is an N multiplied by N dimensional matrix, and the structure of the encoding generating matrix is as follows: column 1 elements take any non-zero value; the N +1 th column element is rotated in phase by an arbitrary angle from the corresponding element of the N-th column with the guarantee that the resulting code symbol is not 0 (N =1,2, …, N-1); each element of each column is completely the same or the columns are orthogonal; each coded symbol obtained after each group of data is coded is a linear combination of all N symbols in a group of data input before coding;
(4) An interleaving device: the interleaving depth is not less than the correlation time of the fast fading channel, so that the channels experienced by the adjacent N symbol codes are mutually independent;
(5) The transmitting device: for transmitting the N symbols of each encoded group of data blocks into the channel successively from the same antenna at different times;
10. the transmitter for time diversity according to claim 9, wherein in the coding means generates a matrix in which the absolute value of the elements of the first column is 1 and the elements of the N +1 th column are rotated in phase by pi/N from the corresponding elements of the N-th column (N =1,2, …, N-1).
11. A communication system for diversity transmission of data block codes, characterized in that it comprises a transmitter as claimed in claim 5 or 9.
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| DE102005040067B4 (en) * | 2005-08-24 | 2007-08-30 | Siemens Ag | Method Transmitter and receiver for encoding data with a differential space-time block code |
| CN100389544C (en) * | 2005-11-11 | 2008-05-21 | 南京邮电大学 | Circulating space-time block code transmitting and diversity project in CDMA system |
| TWI431990B (en) | 2006-01-11 | 2014-03-21 | Interdigital Tech Corp | Method and apparatus for implementing space time processing with unequal modulation and coding schemes |
| CN1835490B (en) * | 2006-04-14 | 2010-05-12 | 南京航空航天大学 | Single pulse antenna time-space modulating method and device with position and elevation information |
| CN101064840B (en) * | 2006-04-26 | 2010-11-03 | 日电（中国）有限公司 | Snake-shaped matrix coder/decoder and visual sign coding and presenting system |
| FR2906659B1 (en) * | 2006-10-03 | 2008-12-19 | Commissariat Energie Atomique | SPATIO-TEMPORAL ENCODING METHOD FOR MULTI-ANTENNA COMMUNICATION SYSTEM OF IMPULSIVE UWB TYPE |
| FR2906658A1 (en) * | 2006-10-03 | 2008-04-04 | Commissariat Energie Atomique | Space time information symbol coding method for ultra wide band multiple input multiple output transmission system, involves coding block of information symbols in sequence of vectors that are defined as elements of matrix |
| CN101247374B (en) * | 2007-12-03 | 2011-03-30 | 南京航空航天大学 | Spacing modulating method for microwave transmitted by multimode horn antenna |
| CN101515817B (en) * | 2009-03-17 | 2014-06-18 | 中兴通讯股份有限公司南京分公司 | Multi-antenna emission diversity method and device |
| CN101841479B (en) * | 2010-04-28 | 2012-12-05 | 四川大学 | High bit-error long time-delay network self-adaptive transmission method based on network coding |
| CN107294581A (en) * | 2016-03-30 | 2017-10-24 | 景略半导体(上海)有限公司 | Multi-antenna transmission, single antenna reception, multi-aerial transmission system and method |
| CN115378545A (en) * | 2021-05-21 | 2022-11-22 | 华为技术有限公司 | Transmission system and transmission method |
| CN114050891B (en) * | 2021-07-22 | 2024-02-27 | 东南大学 | Space-time two-dimensional channel coding method |
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| WO2002052773A1 (en) * | 2000-12-20 | 2002-07-04 | Nortel Networks Limited | Differential space-time block coding |
| CN1501595A (en) * | 2002-10-10 | 2004-06-02 | 三星电子株式会社 | Transmitting and receiving apparatus for supporting transmit antenna diversity using space-time block code |
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| CN1501595A (en) * | 2002-10-10 | 2004-06-02 | 三星电子株式会社 | Transmitting and receiving apparatus for supporting transmit antenna diversity using space-time block code |
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