Multi-tier digital beamforming
A method and apparatus for multi-tier beamforming are disclosed. The method includes receiving a first-tier beamformed frequency-domain IQ data packet and a plurality of second-tier beamformed frequency-domain IQ data packets at a transceiver integrated circuit (IC) subarray. Each transceiver IC of the transceiver IC subarray (i) forms a multi-tier beamformed frequency-domain IQ data set by combining beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets, (ii) generates a discrete-time-domain signal from the multi-tier beamformed frequency-domain IQ data set, and (ii) generates a modulated radio frequency (RF) signal from the discrete-time-domain signal. The method further includes transmitting a multi-tier beamformed signal by transmitting respective modulated RF signals from the transceiver ICs of the transceiver IC subarray via a corresponding adjacent antenna element subarray.
1 . A method comprising:
receiving a first-tier beamformed frequency-domain in-phase and quadrature (IQ) data packet and a plurality of second-tier beamformed frequency-domain IQ data packets at a transceiver integrated circuit (IC) subarray having a plurality of interconnected transceiver ICs, the transceiver ICs interconnected via a plurality of serial data connections;
at each transceiver IC of the transceiver IC subarray:
forming a multi-tier beamformed frequency-domain IQ data set by combining beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets of the plurality of second-tier beamformed frequency-domain IQ data packets;
generating a discrete-time-domain signal from the multi-tier beamformed frequency-domain IQ data set using a digital signal processor (DSP) within the transceiver IC;
generating a modulated radio frequency (RF) signal from the discrete-time-domain signal; and,
transmitting a multi-tier beamformed signal by transmitting respective modulated RF signals from the transceiver ICs of the transceiver IC subarray via a corresponding adjacent antenna element subarray.
2 . The method of claim 1 wherein receiving a first-tier beamformed frequency-domain IQ data packet and a plurality of second-tier beamformed frequency-domain IQ data packets at a transceiver integrated circuit (IC) subarray further comprises:
forwarding the first-tier beamformed frequency-domain IQ data packet from a first transceiver IC of the transceiver IC subarray to additional transceiver ICs of the transceiver IC subarray for common processing; and,
forwarding only a subset of the second-tier beamformed frequency-domain IQ data packets of the plurality of second-tier beamformed frequency-domain IQ data packets from the first transceiver IC to the additional transceiver ICs.
3 . The method of claim 2 wherein the subset of the second-tier beamformed frequency-domain IQ data packets is identified according to packet headers.
4 . The method of claim 1 wherein combining beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets comprises concatenating beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with the beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets prior to a frequency-to-time domain conversion.
5 . The method of claim 1 wherein combining beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets comprises forming a weighted sum of beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with the beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets prior to a frequency-to-time domain conversion.
6 . The method of claim 5 wherein the weighted sum is calculated according to beamforming weights received from a beamformer.
7 . The method of claim 1 wherein combining beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets comprises:
converting the beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet to a first-tier beamformed time-domain signal;
converting the beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets to a second-tier beamformed time-domain signal; and,
adding the first-tier beamformed time-domain signal and the second-tier beamformed time-domain signal.
8 . The method of claim 7 wherein the first-tier beamformed frequency-domain IQ data packet and the selected ones of the second-tier beamformed frequency-domain IQ data packets are associated with different component carriers.
9 . The method of claim 1 wherein receiving the first-tier beamformed frequency-domain IQ data packet and a plurality of second-tier beamformed frequency-domain IQ data packets further comprises receiving second-tier beamformed frequency-domain IQ data packets for processing by transceiver ICs at an end of the transceiver IC subarray prior to receiving second-tier beamformed frequency-domain IQ data packets for processing by transceiver ICs at a beginning of the transceiver IC subarray.
10 . The method of claim 1 wherein transmitting the multi-tier beamformed signal further comprises transmitting respective modulated RF signals from transceiver ICs of a plurality of transceiver IC subarrays via a corresponding plurality of adjacent antenna element subarrays.
11 . An apparatus comprising:
a beamformer processor configured to generate a first-tier beamformed frequency-domain in-phase and quadrature (IQ) data packet and a plurality of second-tier beamformed frequency-domain IQ data packets;
a transceiver integrated circuit (IC) subarray connected to the beamformer processor and having a plurality of interconnected transceiver ICs interconnected via a plurality of serial data connections;
each transceiver IC of the transceiver IC subarray comprising:
a digital signal processor (DSP) configured to form a multi-tier beamformed frequency-domain IQ data set and to generate a discrete-time-domain signal from the multi-tier beamformed frequency-domain IQ data set;
a radio frequency modulator configured to generate a modulated radio frequency (RF) signal from the discrete-time-domain signal; and,
an antenna element subarray connected to the transceiver IC subarray configured to transmit a multi-tier beamformed signal by transmitting respective modulated RF signals from the transceiver ICs of the transceiver IC subarray.
12 . The apparatus of claim 11 wherein the transceiver IC subarray comprises a first transceiver IC having a packet header processor configured to forward the first-tier beamformed frequency-domain IQ data packet from the first transceiver IC to additional transceiver ICs of the transceiver IC subarray for common processing and configured to forward only a subset of the second-tier beamformed frequency-domain IQ data packets from the first transceiver IC to the additional transceiver ICs.
13 . The apparatus of claim 12 wherein the packet header processor is configured to identify the subset of the second-tier beamformed frequency-domain IQ data packets according to packet headers.
14 . The apparatus of claim 11 wherein the DSP is configured to combine beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets by concatenating beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with the beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets prior to a frequency-to-time domain conversion.
15 . The apparatus of claim 11 wherein the DSP is configured to combine beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets by forming a weighted sum of beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet with the beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets prior to a frequency-to-time domain conversion.
16 . The apparatus of claim 15 wherein the DSP is configured to calculate the weighted sum according to beamforming weights received from the beamformer processor.
17 . The apparatus of claim 11 wherein the DSP is configured to:
convert the beamformed frequency-domain IQ data from the first-tier beamformed frequency-domain IQ data packet to a first-tier beamformed time-domain signal;
convert the beamformed frequency-domain IQ data from selected ones of the second-tier beamformed frequency-domain IQ data packets to a second-tier beamformed time-domain signal; and,
add the first-tier beamformed time-domain signal and the second-tier beamformed time-domain signal.
18 . The apparatus of claim 17 further comprising a packet header processor configured to identify separate component carriers associated with the first-tier beamformed frequency-domain IQ data packet and the selected ones of the second-tier beamformed frequency-domain IQ data packets.
19 . The apparatus of claim 11 wherein the beamformer processor is configured to transmit the second-tier beamformed frequency-domain IQ data packets for processing by transceiver ICs at an end of the transceiver IC subarray prior to transmitting second-tier beamformed frequency-domain IQ data packets for processing by transceiver ICs at a beginning of the transceiver IC subarray.
20 . The apparatus of claim 11 further comprising a plurality of transceiver IC subarrays and a corresponding plurality of adjacent antenna element subarrays, configured to transmit the multi-tier beamformed signal.