Multi-code compressed mode DS-CDMA systems and methods
AssigneeTelefonaktiebolaget LM Ericsson
InventorsErik Dahlman, Per Hans P. Willars, Olof E. Grimlund, Lars-Magnus Ewerbring
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Abstract
Introduction of discontinuous transmission in CDMA communications techniques is achieved by selectively using additional spreading codes for spreading a frame of data. By dividing a frame into two or more portions and spreading each portion with a different spreading code, the frame can be transmitted in a compressed mode wherein the information is transmitted during a portion of the frame period, leaving an idle part of the frame in which to perform other functions, such as evaluation of other frequencies for use in handover between frequencies.
Claims41
A method of code division multiple access in cellular communications, wherein information is transmitted in frames having a specific time duration, said method comprising the steps of:
- impressing, in a normal mode, a frame of data to be transmitted on P signature sequences to produce a spread information signal;
- impressing, in a compressed mode, said frame of data on Q signature sequences, wherein Q is greater than P, to produce a compressed spread information signal;
- and
- transmitting one of said spread information signal and said compressed spread information signal;
- wherein a frame transmitted in said compressed mode includes a first part having a time duration less than said specific time duration and containing a complete coded information signal, and a second part during which said transmitter is idle.
An apparatus for transmitting information in a code division multiple access system transmitting information in frames of specific time duration, said apparatus comprising:
- means for spreading data in either a normal mode, wherein a normal mode frame includes said information spread using at least one spreading code, or a compressed mode wherein a frame of data is spread using said at least one spreading code and at least one additional spreading code;
- and wherein a compressed frame includes a first part of less than said specific time duration, said first part containing a complete information signal, and a second part;
- means for controlling which of said compressed mode and said normal mode is used in said spreading means;
- and
- means for transmitting an output of said spreading means.
A CDMA transmitter comprising:
- a channel coder for convolutionally encoding a frame of data bits;
- a modulator for modulating said encoded frame of data bits;
- a first spreading unit for receiving a first spreading code;
- a second spreading unit for receiving a second spreading code;
- and
- a mode control device for passing said modulated, encoded frame of data bits to said first spreading unit when said transmitter is operated in a normal mode, and for passing a first portion of said encoded frame of data bits to said first spreading device and a second portion of said encoded frame of data bits to said second spreading device when said transmitter is operating in a compressed mode.
A method of code division multiple access in cellular communications, said method comprising the steps of:
- impressing, in a normal mode, a frame of data to be transmitted on P signature sequences to produce a spread information signal;
- impressing, in a compressed mode, said frame of data on Q signature sequences, wherein Q is greater than P, to produce a compressed spread information signal;
- and
- transmitting one of said spread information signal and said compressed spread information signal.
An apparatus for transmitting information in a code division multiple access system, said apparatus comprising:
- means for impressing, in a normal mode, a frame of data to be transmitted on P signature sequences to produce a spread information signal;
- means for impressing, in a compressed mode, said frame of data on Q signature sequences, wherein Q is greater than P, to produce a compressed spread information signal;
- and
- means for transmitting one of said spread information signal and said compressed spread information signal.
Dependencies are inferred from the claim text.