CDMA multiuser receiver featuring a combination of array antenna and multiuser cancelers

• US 6,222,498 B1
• Filed: 01/08/1999
• Issued: 04/24/2001
• Est. Priority Date: 01/08/1998
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ishii, Naoto, Ushirokawa, Akihisa, Yoshida, Shousei, Maruta, Yasushi
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Clinger, James
• Application Number:
  US09/227,705
• Time in Patent Office: 837 Days
• Field of Search: 342/354, 375/349, 375/206, 455/12.1, 455/13.1, 455/506, 701/213, 370/342, 370/491
• US Class Current: 343/853
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation
• CPC Class Codes: H04B 2201/70707 Efficiency-related aspects
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: H04B 7/0882 using post-detection diversity
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/03331 Arrangements for the joint estimation of multiple sequences

Abstract

In order to effectively reduce a size of CDMA multiuser receiver while maintaining an excellent interference cancellation, an array antenna is combined with a multiuser receiver. The multiuser receiver includes signal processing means which is supplied with incoming signals received at the array antenna. The signal processing means estimates interfering signals with respecting to each of the antenna elements and with respect to each of simultaneously accessing users.

Claims

1. A CDMA (code division multiple access) multiuser receiver comprising:

an array antenna including a plurality of antenna elements;

a plurality of antenna weighting coefficient determiners, respectively coupled to said plurality of antenna elements, for producing a plurality of antenna weighting coefficients for use in estimating and canceling the interfering signals;

a multiuser receiver coupled to said array antenna, said multiuser receiver including signal processing means which is supplied with signals from said array antenna, said signal processing means estimating and canceling interfering signals with respect to each of said plurality of antenna elements and with respect to each of simultaneously accessing users;

wherein said signal processing means comprises at least two interference cancelers arranged in tandem, one of said two interference cancelers comprising;

a plurality of IEUs (interference estimation units) which are respectively dedicated to the users, each of said plurality of IEUs coupled to receive the signals from said plurality of antenna elements and produce, using said antenna weighting coefficients, an interference estimating signal with respect to the dedicated user and with respect to each of said plurality of antenna elements;

a plurality of first adders which are respectively coupled to said plurality of antenna elements, each of said first adders subtracting, from the signal applied thereto from the corresponding antenna element, the interference estimating signals of all the users with respect to the corresponding antenna element; and

a plurality of adder groups whose number equals the number of IEUs, each of said adder groups including a plurality of second adders whose number equals the number of the antenna elements and which are respectively coupled to receive the outputs of said first adders, each of said second adders adding the output of the corresponding first adder and the interference estimating signal outputted from the corresponding IEU with respect to the corresponding antenna element.

2. The CDMA multiuser receiver as claimed in claim 1, further comprising a plurality of delays, respectively provided between said plurality of antenna elements and said plurality of first adders, for delaying the signals from the respective antenna elements so as to respectively compensate for delay induced at said plurality of IEUs.

3. A CDMA (code division multiple access) multiuser receiver comprising:

an array antenna including a plurality of antenna elements;

a plurality of antenna weighting coefficient determiners, respectively coupled to said plurality of antenna elements, for producing a plurality of antenna weighting coefficients for use in estimating and canceling the interfering signals;

a multiuser receiver coupled to said array antenna, said multiuser receiver including signal processing means which is supplied with signals from said array antenna, said signal processing means estimating and canceling interfering signals with respect to each of said plurality of antenna elements and with respect to each of simultaneously accessing users;

wherein said signal processing means comprises at least two interference cancelers arranged in tandem, one of said two interference cancelers comprises;

a plurality of IEUs which are respectively dedicated to the users, each of said plurality of IEUs coupled to receive the signals from said plurality of antenna elements and produce, using said antenna weighting coefficients, an interference estimating signal with respect to the dedicated user and with respect to each of said plurality of antenna elements, each of said plurality of IEUs further producing an estimated signal with respect to the dedicated user; and

a plurality of adders which are respectively coupled to said plurality of antenna elements, each of said adders subtracting, from the signal applied thereto from the corresponding antenna element, the interference estimating signals off all the users with respect to the corresponding antenna element.

4. The CDMA multiuser receiver as claimed in claim 3, further comprising a plurality of delays, respectively provided between said plurality of antenna elements and said plurality of first adders, for delaying the signals from the respective antenna elements so as to respectively compensate for delay induced at said plurality of IEUs.