CDMA frequency allocation

• US 5,341,397 A
• Filed: 12/08/1993
• Issued: 08/23/1994
• Est. Priority Date: 04/13/1992
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Gudmundson, Bjorn
• Primary Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US08/162,948
• Time in Patent Office: 258 Days
• Field of Search: 375/1, 455/68
• US Class Current: 370/335
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04W 16/00 Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A Code Division Multiple Access (CDMA) communication system which allocates different sets of frequencies to cells with different transmission power levels. Based upon the transmission power levels of a base station for each cell, each base station is assigned to one of at least two groups of base stations. Each group of base stations is assigned a set of frequencies for traffic communication. The set of frequencies assigned to one group of base stations does not overlap with the set of frequencies assigned to a different group of base stations.

Claims

1. In a multiple access, spread spectrum communication system for communication information signals, which include speech, control and pilot-sequence signals, between a plurality of base station and a plurality of mobile stations, a method comprising:

coding blocks of bit sequences of an information signal;

scrambling each said coded information signal using a unique selected scrambling bit sequence;

transmitting said scrambled coded signals from each base station;

receiving a composite signal of overlapping, transmitted signals;

descrambling said composite signal using one of said unique scrambling bit sequences to distinguish coded information signals from a selected base station from other signals in said composite signal;

recursively correlating said composite signal with block codes corresponding to said information signals;

determining which block code generates a greatest correlation and producing a correlated signal;

successively removing said correlated signal from said composite signal;

rescrambling a residual portion of said correlated, composite signal using said corresponding block codes to generate a series of recorded signals;

detecting received pilot-sequence signals;

measuring the signal strength of each received pilot sequence signal; and

storing the measured signal strengths of the received pilot sequences.

2. A method of communication in a code division multiple access system according to claim 1, further comprising the step of:

regularly transmitting the stored signal strengths to a base station.

3. A method of communication in a code division multiple access system according to claim 1, further comprising the step of:

transmitting the stored signal strengths to a requesting base station.

4. In a multiple access, spread spectrum communication system for communicating information signals, which include speech, control and pilot-sequence signals, between a plurality of base stations and a plurality of mobile stations, a transmitter in each base station including:

coding means for coding blocks of bit sequences of an information signal,

means for scrambling each information signal using a unique selected scrambling bit sequence corresponding to one of said base stations, and

means for transmitting said block coded information signal; and

receiving means in each mobile station for receiving a composite signal of overlapping, transmitted signals, including;

descrambling means for descrambling said composite signal using one of said unique scrambling bit sequences to distinguish coded information signals from a selected base station from other signals in said composite signal;

correlation means for recursively correlating said composite signal with block codes corresponding to said information signals;

comparison means for determining a block code that generates a greatest correlation and for producing a correlated signal;

signal removal means for successively removing said correlated signal from said composite signal;

rescrambling means for recording a residual portion of said correlated, composite signal using said corresponding block codes to generated a series of recorded signals;

detection means for detecting received pilot-sequences;

measuring the relative signal strength of each received pilot sequence; and

storing the measured signal strengths of the received pilot sequences.

5. The system according to claim 4, wherein said block codes are formed using Walsh-Hadamard matrices.

6. The system according to claim 4, wherein said block codes are orthogonal block codes.

7. The system according to claim 4, wherein said block codes are bi-orthogonal block codes.