Transmission de-correlator for eliminating interference in a CDMA communication system

• US 5,500,856 A
• Filed: 07/28/1994
• Issued: 03/19/1996
• Est. Priority Date: 07/30/1993
• Status: Expired due to Fees

• Current Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation), Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation), Matsushita Communication Industrial Co Ltd (Panasonic Holdings Corporation)
• Inventors: Matsumoto, Tadashi, Higashi, Akihiro, Nagase, Taku, Go, Roland
• Primary Examiner(s): Kizou, Hassan
• Application Number:
  US08/281,640
• Time in Patent Office: 600 Days
• Field of Search: 370/18, 370/95.1, 370/95.3, 375/1, 375/34, 375/58, 375/60, 375/205, 375/206, 375/210, 375/346, 379/58, 379/59, 455/33.1, 455/50.1, 455/53.1, 455/54.1, 455/57.1, 455/63, 455/38.3, 455/343, 380/34
• US Class Current: 370/441
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 2201/709709 Methods of preventing interference
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker
• CPC Class Codes: H04J 13/16 Code allocation

Abstract

A base station of a CDMA communication system includes a transmission de-correlator for eliminating interferences between communication channels of a downlink. The transmission de-correlator has a memory storing a set of data representative of the products of transmission information bits for the respective channels, and the sums of the products of the spread code data sequences for the respective channels, and the elements of an inverse matrix with respect to a predetermined matrix of a cross-correlation between the spread code data sequences for the respective channels. The sums correspond to additions of the products along a direction of columns or to additions of the products along a direction of rows of the inverse matrix. A counting device is operative for causing the memory to sequentially output the data therefrom. An adder serves to calculate a sum of the data outputted from the memory.

Claims

1. In a base station of a CDMA communication system, a transmission de-correlator for eliminating interferences between communication channels of a downlink, comprising:

a memory means for storing a set of data representative of the products of transmission information bits for the respective channels, and the sums of the products of the spread code data sequences for the respective channels, and the elements of an inverse matrix with respect to a predetermined matrix of a cross-correlation between the spread code data sequences for the respective channels, wherein said sums correspond to additions of the products along the columns of said inverse matrix or to additions of the products along the rows of the inverse matrix;

a counting means connected to an address input of said memory means for causing the memory means to sequentially output the data therefrom; and

an adder connected to receive data from said memory means for calculating a sum of the data received from the memory means.

2. In a base station of a CDMA communication system, a transmission de-correlator for eliminating interferences between communication channels of a downlink, comprising:

a memory means for storing a set of data representative of the products of multi-bit transmission information pieces for the respective channels, and the sums of the products of the spread code data sequences for the respective channels, and the elements of an inverse matrix with respect to a predetermined matrix of a cross-correlation between the spread code data sequences for the respective channels, wherein said multi-bit transmission information pieces contain power information pieces for power controls of the respective channels, and wherein said sums correspond to additions of the products along the columns or to additions of the products along the rows of the inverse matrix;

a counting means connected to an address input of said memory means for causing the memory means to sequentially output the data therefrom; and

an adder for receiving data from said memory means and for calculating a sum of the data outputted from the memory means.

3. In a base station of a CDMA communication system, a transmission de-correlator for eliminating interferences between communication channels of a downlink, comprising:

means for generating information pieces to be transmitted for the respective channels;

a storage unit including a plurality of memories;

means for applying the generated information pieces to the memories as a first portion of an address signal, respectively;

means for generating a second periodically repeated portion of the address signal to the memories, respectively;

wherein each of the memories contains a plurality of storage segments which are designated by different states of a related address signal, respectively, said storage segments storing respective predetermined data pieces, wherein said predetermined data pieces depend on products of possible states of the information piece to be transmitted for a related communication channel, predetermined spread codes, and elements of an inverse matrix with respect to a predetermined matrix of a cross-correlation between the spread codes, and wherein in each of the memories, one of the storage segments is accessed in response to the related address signal and the data piece is outputted from the accessed storage segment; and

means for adding data pieces outputted from the memories.