Matched filter and correlation detection method

A method for carrying out correlation detection of known original signals with periodicity included in a received spread spectrum signal, comprising the steps of:

• multiplying a reception signal by a spreading code and carrying out despreading;
• extracting a plurality of sets of data bits in a relative positional relationship that matches said periodicity of said known original signals in the despread data bit string and carrying out a first cumulative addition;
• multiplying said data string subjected to said cumulative addition by said known original signals;
• and
• carrying out a second cumulative addition on the data string obtained by multiplying said original signals and carrying out correlation detection.

A correlation detection method whereby a spread spectrum signal obtained by multiplying a common spreading code on original signals formed by consecutively repeating one data bit pattern selected from a plurality of types of known data bit patterns, with periodicity and the same number of types as said known data bit patterns is received, predetermined calculation is performed and thereby a correlation on said original signals is detected, comprising:

• multiplying the reception signal by said common spreading code and carrying out despreading;
• extracting a set of data bits in a positional relationship that matches said period of said original signals from a data string obtained as a result of despreading for every said positional relationship, obtaining a plurality of sets of data bits as a result, carrying out a cumulative addition on the data bits for every set of said plurality of sets of data bits and calculating a cumulative addition value for every set;
• multiplying the data string subjected to said cumulative addition by each of said plurality of original signals in parallel or sequentially at different times;
• and
• executing a cumulative addition for every result obtained by multiplying one original signal, detecting a correlation for each of said plurality of original signals and thereby detecting said original signals included in the reception signal.

A correlation detection method on the receiving side in a communication system whereby original signals with a periodic array formed by repeating a unit pattern made up of n (n:

• natural number of 2 or greater) symbols m (m:
• natural number of 2 or greater) times, capable of taking p types of symbol array with different contents as a result of the existence of p (p:
• natural number of 2 or greater) types of said unit patterns are provided beforehand, synchronization establishment signals are generated by multiplying each of said p types of original signals by a common spreading code, said synchronization establishment signals sent from the other end of communication are received, correlation detection is performed, it is judged whether said synchronization establishment signals have been received or not, and thereby the receiving side judges the request from said other end of communication or obtains information to acquire synchronization to carry out a communication, comprising:
• a multiplying step of multiplying said synchronization establishment signals received by said common spreading code and carrying out despreading;
• a first cumulative addition step of delimiting a symbol string obtained as a result of the despreading in units of n symbols, extracting symbols at a same position for every m sections, executing a cumulative addition for every set of the extracted m symbol data portions and obtaining am n-symbol data string as a result;
• an original signal multiplying step of branching said n-symbol data string obtained as a result of said first cumulative addition into at least two lines, multiplying each of the branched data strings by each of said p types of original signals in parallel or multiplying said n-symbol data string obtained as a result of said first cumulative addition by each of p types of original signals at different times sequentially and thereby outputting the symbol data string of the multiplication result for each of p types of original signals;
• and
• a second cumulative addition step of executing a cumulative addition on each of the symbol data strings which are the multiplication results output for each of said p types of original signals and outputting a cumulative addition result for each of p types of original signals.

A synchronization establishment search method whereby a plurality of types of known codes with a certain period is provided, a synchronization establishment signal is generated by multiplying any one of said known codes by a common spreading signal, a base station apparatus that receives a spread spectrum signal in which said synchronization establishment signal is inserted detects said synchronization establishment signal included in the reception signal and carries out synchronization establishment processing for a communication, comprising:

• a step of multiplying each of an in-phase signal (I signal) and quadrature signal (Q signal) received by a common spreading code and carrying out despreading;
• a first cumulative addition step of extracting a plurality of symbols in a relative positional relationship corresponding to the cycle of said known code for each of the despread I signal and Q signal and carrying out a cumulative addition;
• a step of multiplying each of the I signal and Q signal after the first in-phase addition by each of said plurality of types of known codes;
• a second cumulative addition step of carrying out a cumulative addition on each symbol string obtained by multiplying said known code;
• and
• a step of calculating reception power by finding squares of correlation values of the I signal and Q signal obtained from said second cumulative addition and adding up said squares and obtaining timing information for establishing communication synchronization based on the calculated reception power.

A matched filter used for correlation detection on the receiving side in a communication system whereby original signals with a periodic array formed by repeating a unit pattern made up of n (n:

• natural number of 2 or greater) symbols m (m:
• natural number of 2 or greater) times, capable of taking p types of symbol array with different contents as a result of the existence of p (p:
• natural number of 2 or greater) types of said unit patterns are provided beforehand, synchronization establishment signals are generated by multiplying each of said p types of original signals by a common spreading code, said synchronization establishment signals sent from the other end of communication are received, correlation detection is performed, it is judged whether said synchronization establishment signals have been received or not, and thereby the receiving side judges the request from said other end of communication or obtains timing information to acquire synchronization for a communication with said other end of communication, comprising:
• a despreading section that multiplies said synchronization establishment signals received by said common spreading code and carries out despreading;
• a first cumulative addition section that delimits a symbol string obtained as a result of the despreading in units of n symbols, extracts symbols at a same position for every m sections, executes a cumulative addition for every set of the extracted m symbol data portions and obtains an n-symbol data string as a result;
• an original signal multiplication section that branches said n-symbol data string obtained into at least two lines, multiplies each of the branched data strings by each of said p types of original signals in parallel or multiplies said n-symbol data string obtained as a result of said first cumulative addition section by each of p types of original signals at different times sequentially and thereby outputs the symbol data string of the multiplication result for each of p types of original signals;
• and
• a second cumulative addition section that executes a cumulative addition on each of the symbol data strings which are the multiplication results output for each of said p types of original signals and outputs a cumulative addition result for each of p types of original signals.

A matched filter used for correlation detection on the receiving side in a communication system whereby original signals with a periodic array formed by repeating a unit pattern made up of n (n:

• natural number of 2 or greater) symbols m (m:
• natural number of 2 or greater) times, capable of taking p types of symbol array with different contents as a result of the existence of p (p:
• natural number of 2 or greater) types of said unit patterns are provided beforehand, synchronization establishment signals are generated by multiplying each of said p types of original signals by a common spreading code, said synchronization establishment signals sent from the other end of communication are received, correlation detection is performed, it is judged whether said synchronization establishment signals have been received or not, and thereby the receiving side judges the request from said other end of communication, comprising:
• a despreading section that multiplies said synchronization establishment signals received by said common spreading code and carries out despreading;
• a first cumulative addition section that delimits a symbol string obtained as a result of the despreading in units of n symbols, extracts symbols at a same position for every m sections, executes a cumulative addition for every set of the extracted m symbol data portions and obtains an n-symbol data string as a result;
• a memory that temporarily stores an addition result of said first cumulative addition section;
• an original signal multiplication section that carries out processing of multiplying the n-symbol data read from said memory at a predetermined speed by each of said p types of original signals at a speed s times (s:
• integer of 2 or greater) the reading speed from said memory using at least two lines of multipliers that operate in parallel and thereby outputs symbol data of the multiplication results for each of p types of original signals;
• and
• a second cumulative addition section that executes a cumulative addition on a set of symbol data portions which are the multiplication results output for each of said p types of original signals from this multiplying means and outputs a cumulative addition result for each of p types of original signals.

A CDMA communication base station apparatus that receives a CDMA-based signal including known codes with predetermined periodicity made up of an array formed by repeating a basic data bit pattern, detects the existence of known codes with said predetermined periodicity, and thereby identifies the request of the mobile station that has sent the signal including the known codes or obtains information to acquire synchronization for a communication with said mobile station, comprising:

• a matched filter comprising a despreading section that multiplies the reception signal by a spreading code and carries out despreading, a first cumulative addition section that extracts a set of data bits in a positional relationship that matches said cycle of said known codes for every said positional relationship and thereby obtains a plurality of sets of data bits as a result, executes a cumulative addition on data bits for every set of said plurality of sets of data bits and calculates a cumulative addition value for every set, a multiplication section that multiplies the addition result of said first adding means by said known codes, a second cumulative addition section that executes a cumulative addition on each bit of the data string output from said multiplication section and obtains a correlation value for said known codes;
• and
• a timing information acquisition section that calculates power of the reception signal using the correlation values output from said matched filter and acquires timing information to establish synchronization for a communication with said mobile station using the power.