Scalable, multi-layer MIMO transceiver
Disclosed herein is an innovative multi-layer hybrid/digital MIMO architecture that comprises single-stream or fully-connected (FC) multi-stream beamforming tiles (with RF complex-weights) in the first layer, followed by a fully connected (analog/digital) baseband layer. This architecture overcomes the complexity versus spectral-efficiency tradeoffs of existing hybrid MIMO architectures and enables MIMO stream/user scalability, superior energy-efficiency, and spatial-processing flexibility.
1. A multi-layer, MIMO beamforming transceiver comprising:
K tiles comprising N A antenna elements;
a first layer interfacing the N A antenna elements to N RF frequency translation chains; and
a second layer implementing fully-connected, bi-directional spatial signal processing between the N RF frequency translation chains and N S streams;
wherein the K tiles are fully-connected; and
wherein N RF =2K.
2. The transceiver of claim 1 wherein the first layer applies RF-domain complex weighting to the N RF frequency translation chains.
3. The transceiver of claim 1 wherein the spatial signal processing in the second layer occurs in the analog domain.
4. The transceiver of claim 1 wherein the fully-connected beamforming in the second layer occurs in the digital domain.
5. The transceiver of claim 1 wherein complex weights are applied to received frequency translation chains to spatially separate the NS streams.
6. The transceiver of claim 1 comprising a receive path using a Cartesian combining architecture to perform RF domain beamforming in each stream of each fully-connected tile in the first layer.
7. The transceiver of claim 1 comprising a transmit path using a Cartesian-splitting architecture to perform RF domain beamforming in each stream of each fully-connected tile in the first layer.
8. The transceiver of claim 1 further comprising:
a low-noise amplifier/power amplifier dual-band bi-directional interface connected to each antenna element.
9. The transceiver of claim 8 further comprising:
a dual-band bi-directional beamforming network with shared passives between transmit and receive paths, coupled to the low-noise amplifier/power amplifier interfaces.
10. The transceiver of claim 9 further comprising:
N S homodyne complex-quadrature up/down conversions stages, coupled to the beamforming network, one stage per stream respectively.
11. The transceiver of claim 10 further comprising:
a dual-band local oscillation generation and distribution network.
12. The transceiver of claim 11 further comprising:
a three-step self-interference cancellation (SIC) mechanism.
13. The transceiver of claim 12 wherein a first step of the three-step SIC mechanism comprises:
using one stream in each receive beamformer to inject a complex-weighted transmit signal at an output node of each low-noise amplifier.
14. The transceiver of claim 13 wherein the complex weights are dynamically computed using a minimum-mean-square-error criterion to minimize the residual self-interference using a least-mean-squared algorithm.
15. The transceiver of claim 14 wherein the least-mean-squared algorithm uses time-multiplexed error extraction.
16. The transceiver of claim 13 wherein a second step of the three-step SIC mechanism comprises:
using beamforming degrees of freedom in the receive portion of the beamforming network to minimize residual self-interference after beamforming.
17. The transceiver of claim 16 wherein a third step of the three-step SIC mechanism comprises:
injecting a self-interference cancellation signal after the RF-domain receive beamforming at an input of a downconversion stage.
18. The transceiver of claim 17 wherein further self-interference cancellation is performed at baseband stage in either the analog or digital domains.
19. The transceiver of claim 17 wherein the first and third step cancellations use a transmit signal copy with digital domain delay to achieve wideband self-interference cancellation.
20. A multi-layer, MIMO beamforming transceiver comprising:
K tiles comprising N A antenna elements;
a first partially-connected layer interfacing the N A antenna elements to N RF frequency translation chains; and
a second fully-connected analog layer implementing bi-directional spatial signal processing between the N RF frequency translation chains and N S streams;
wherein N RF =K.
21. A multi-layer, MIMO beamforming transceiver comprising:
K tiles comprising N A antenna elements;
a first fully-connected layer interfacing the N A antenna elements to N RF frequency translation chains; and
a second fully-connected digital layer implementing bi-directional spatial signal processing between the N RF frequency translation chains and the N S streams;
wherein N RF =2K.
22. A multi-layer, MIMO beamforming transceiver comprising:
K tiles comprising N A antenna elements;
a first fully-connected layer interfacing the N A antenna elements to N RF frequency translation chains; and
a second fully-connected analog layer implementing bi-directional spatial signal processing between the N RF frequency translation chains and the N S streams;
wherein N RF =2K.
23. The transceiver of claim 22 further comprising:
a third, fully-connected digital layer coupled to the second layer via a plurality of analog-to-digital converters.