초록 ▼

A unique system for efficiently implementing filtered, phase shifted channels is disclosed. Instead of using separate transmit shaping filters for each channel, and modulating the filtered signals with phase-shifted carrier and one might suppose, the system phase rotates the signals for each channel

A unique system for efficiently implementing filtered, phase shifted channels is disclosed. Instead of using separate transmit shaping filters for each channel, and modulating the filtered signals with phase-shifted carrier and one might suppose, the system phase rotates the signals for each channel and modulates such phase rotated signals with a single carrier. In addition, the system decomposes the phase rotations into 90.degree. pre-filter portions and a post-filter portion of, for example, 45.degree.. In an 8 channel system, such as proposed in the IS-95B standard, the channels are divided into two groups and the 90.degree. phase rotations for each group are done at the input of the transmit shaping filters. A 45.degree. phase rotation is then done for one of the groups at the output of the transmit shaping filter. Significantly, no multiplication is required.

대표청구항 ▼

[ What is claimed is:] [8.] A wireless communication system for transmitting eight digital baseband streams over eight code-channels in a wireless channel, the code-channels having predetermined phase offsets when modulated with a carrier, the code-channels being grouped into first and second groups

[ What is claimed is:] [8.] A wireless communication system for transmitting eight digital baseband streams over eight code-channels in a wireless channel, the code-channels having predetermined phase offsets when modulated with a carrier, the code-channels being grouped into first and second groups of code-channels wherein the individual code-channels in each group have a phase offset of 0.degree. or 90.degree. and wherein the first and second groups as a whole have a phase offset of .DELTA..sub.GROUP.degree., the system comprising:means for converting each digital baseband stream into inphase and quadrature signals I, Q;means for grouping a first plurality of the code channels into a first orthogonal group of code channels comprising zero-degree channels which require a total phase rotation of 0.degree. and ninety-degree channels which require a total phase rotation of 90.degree.;means for grouping a second plurality of the code channels into a second orthogonal groups of code channels comprising zero-plus-delta degree channels which require a total phase rotation of 0.degree.+.DELTA..sub.GROUP.degree. and ninety-plus-delta degree channels which require a total phase rotation of 90.degree.+.DELTA..sub.GROUP.degree.;first and second pre-filter means for phase-rotating the inphase and quadrature signals I, Q of the ninety-degree channels by 90.degree. to form phase rotated signals I.sub.90, Q.sub.90 by setting I.sub.90 =Q and Q.sub.90 Q=-I;first and second pre-filter means for combining the signals I, Q of the zero-degree channels with the signals I.sub.90, Q.sub.90 of the ninety-degree channels to form combined signals I.sub.A, Q.sub.A and I.sub.B, Q.sub.B, respectively;first means for filtering the combined signals I.sub.A, Q.sub.A to form filtered signals I.sub.A ', Q.sub.A ' that are better suited for transmission over the wireless channel;second means for filtering the combined signals I.sub.B, Q.sub.B to form filtered signals I.sub.B ', Q.sub.B ' that are better suited for transmission over the wireless channel, said second filtering means further comprising means for scaling the filtered signals I.sub.B ', Q.sub.B ' with phase-rotation coefficients K.sub.I, K.sub.Q to produce scaled and filtered signals K.sub.I I.sub.B ', K.sub.Q Q.sub.B ';post-filter means for phase-rotating the scaled and filtered signals K.sub.I I.sub.B ', K.sub.Q Q.sub.B ' by mathematically processing such signals to produce filtered and phase-rotated signals I.sub.B ", Q.sub.B "; andmeans for combining the phase-rotated and filtered signals I.sub.A ', Q.sub.A ' and the phase-rotated and filtered phase-rotated signals I.sub.B ", Q.sub.B " to form final signals I.sub.FINAL, Q.sub.FINAL.