Device and method for synchronizing and channel estimation in a TDMA radio communication system
First Claim
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1. A method of channel estimation in a TDMA radio communication system comprising the steps of:
 calculating a center of energy value w of a first vector having M correlation values between a synchronization sequence and M parts of a signal frame, which are partially overlapping and mutually displaced one sampling interval, substantially in accordance with the formula ##EQU5## where c(k) designates a correlation value in position k in said first vector and M is an integer;
rounding the value w to a nearest integer to form a preliminary window center position m_{w} in said first vector; and
choosing N consecutive correlation values distributed around said preliminary window center position m_{w} to form a second vector of N correlation values for channel estimation where N is an integer.
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Abstract
A method of synchronizing a received signal frame in a TDMA radio system with a locally generated (TR) training sequence and of determining a channel estimate based on the comparison the received signal frame and the locally generated training sequence. A center of energy value is calculated for a first vector having M correlation values. A second vector having N consecutive correlation values distributed around the center of energy is chosen to form the channel estimate. The center of energy in the second vector can be chosen as synchronizing position.
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23 Claims

1. A method of channel estimation in a TDMA radio communication system comprising the steps of:

calculating a center of energy value w of a first vector having M correlation values between a synchronization sequence and M parts of a signal frame, which are partially overlapping and mutually displaced one sampling interval, substantially in accordance with the formula ##EQU5## where c(k) designates a correlation value in position k in said first vector and M is an integer; rounding the value w to a nearest integer to form a preliminary window center position m_{w} in said first vector; and choosing N consecutive correlation values distributed around said preliminary window center position m_{w} to form a second vector of N correlation values for channel estimation where N is an integer.  View Dependent Claims (2, 3, 4, 5)


6. A method for channel estimation in a TDMA radio communication system comprising the steps of:

calculating a center of energy value w of a first vector having M correlation values between a synchronization sequence and M parts of a signal frame, which are partially overlapping and mutually displaced one sampling interval, substantially in accordance with the formula ##EQU6## where c(k) designates a correlation value in position k in said first vector and M is an integer; rounding the value w to a nearest integer to form a preliminary window center position m_{w} in said first vector; choosing 2L+1 partially overlapping vectors which are mutually time displaced one sampling interval, each comprising N consecutive correlation values distributed around said preliminary window center position m_{w}, where N=2K+1 and K, L, and N are integers; and choosing a vector from the 2L+1 chosen vectors that has a largest energy content E_{n}, that is that vector that maximizes the expression ##EQU7## as a second vector of N correlation values for channel estimation where c(j+m_{w} +n)^{2} designates a correlation value magnitude.  View Dependent Claims (7, 8, 9, 10, 11, 12)


13. A method for channel estimation in a TDMA radio communication system comprising the steps of:

calculating a center of energy value w of a first vector having M correlation values between a synchronization sequence and M parts of a signal frame, which are partially overlapping and mutually displaced one sampling interval, substantially in accordance with the formula ##EQU10## where c(k) designates a correlation value in position k in said first vector and M is an integer; rounding the value w to a nearest integer to form a preliminary window center position m_{w} in said first vector; choosing two partially overlapping vectors which are mutually time displaced one sampling interval, each comprising N consecutive correlation values surrounding said preliminary window center position m_{w}, where N=2K+1 and K and N are integers; and choosing a vector from the two chosen vectors that has a largest energy content E_{n}, that is that vector that maximizes the expression ##EQU11## as a second vector of N correlation values for channel estimation where c(j+m_{w} +n)^{2} designates a correlation value magnitude.  View Dependent Claims (14, 15, 16, 17)


18. A method of determining a synchronization position m of a signal frame in a vector in a TDMA radio communication system, said vector comprising M correlation values between a synchronization sequence and M parts of said signal frame, which parts are partially overlapping and mutually time displaced one sampling interval, comprising the steps of:
calculating a center of energy w substantially in accordance with the formula ##EQU13## where c(k) designates a correlation value in position k in said vector and m is an integer, said calculated center of energy value w forming said synchronization position m.

19. A device in a TDMA radio communicating system for allowing determination of a synchronization position comprising:

means for correlating a training sequence with a complex input signal to provide correlation values and correlation value magnitudes; a calculator having an input to receive said correlation value magnitudes and an output to provide a weighted average of said correlation value magnitudes; a first summation unit having an input to receive said correlation value magnitudes and an output to provide a sum of the correlation value magnitudes; a divider having a first input connected to receive said calculator output as a dividend and a second input connected to receive said first summation unit output as a divisor and an output to provide a quotient, said quotient being a center of energy value w; means for rounding having an input connected to receive said divider output and an output to provide a value m_{w}, said value m_{w} being the center of energy value w rounded to a nearest integer; a second summation unit having a first input connected to receive said correlation value magnitudes and a second input connected to receive said rounding means output and an output to provide an energy value for each of a plurality of windows distributed about position m_{w} and mutually displaced one sampling step; means for detecting a maximum value having an input connected to receive said second summation unit output and an output to provide a window selected from said plurality of windows having a maximum energy value, said selected window having a center position m allowing for determination of said synchronization position.  View Dependent Claims (20, 21, 22, 23)

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