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US 2018/0294861 A1Published application
Beamforming in a mu-mimo wireless communication system
AssigneeRF DSP Inc.
InventorsPing LIANG, Dengkui ZHU, Boyu LI
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Abstract
This invention provides methods for Distributed Massive MIMO (DM-MIMO) that use one or more central Baseband Units (BBUs), one or more Multi-User Beamformers for each BBU performing multi-user MIMO computations, and a number of RRHs distributed over a geographic area.
Claims17
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A method for Distributed Massive MIMO (DM-MIMO) comprising
- Using one or more central Baseband Units (BBUs), connected by a backhaul to a core network, to perform baseband signal processing;
- One or more Multi-User Beamformers for each Baseband Unit performing multi-user MIMO computations for antennas on all Remote Radio Heads (RRHs) connected to it or for antennas on one or more clusters of RRHs connected to it to achieve a high order of spatial multiplexing over the entire coverage area with low inter-beam interference.
- A number of RRHs distributed over a geographic area transmitting and receiving wherein each RRH contains a plural of antennas, RF transceivers and a synchronization circuit and is connected to a Multi-User Beamformer via an optical fiber, cable or a wireless link fronthaul connection;
- and,
- A BBU listening to the pilot signals transmitted by one or more UEs covered by a neighboring cell, using the received pilot signals to estimate the channel with the said UEs, computing a pre-coding matrix to make the transmissions by the BBU's RRHs orthogonal to the channels to the said UEs in the neighboring cell.
2 more elements
A method for Distributed Massive MIMO (DM-MIMO) comprising
- Using one or more central Baseband Units (BBUs), connected by a backhaul to a core network, to perform baseband signal processing;
- One or more Multi-User Beamformers for each Baseband Unit performing multi-user MIMO computations for antennas on all Remote Radio Heads (RRHs) connected to it or for antennas on one or more clusters of RRHs connected to it to achieve a high order of spatial multiplexing over the entire coverage area with low inter-beam interference;
- A number of RRHs distributed over a geographic area transmitting and receiving wherein each RRH contains a plural of antennas, RF transceivers and a synchronization circuit and is connected to a Multi-User Beamformer via an optical fiber, cable or a wireless link fronthaul connection, and,
- Performing a first-level beamforming for each RRH or each cluster of RRHs, then considering all antennas on each of such RRH or cluster of RRHs as a single antenna and performing a second-level beamforming among multiple of such RRHs or clusters of RRHs.
1 more element
A method for Distributed Massive MIMO (DM-MIMO) comprising
- Using one or more central Baseband Units (BBUs), connected by a backhaul to a core network, to perform baseband signal processing;
- One or more Multi-User Beamformers for each Baseband Unit performing multi-user MIMO computations for antennas on all Remote Radio Heads (RRHs) connected to it or for antennas on one or more clusters of RRHs connected to it to achieve a high order of spatial multiplexing over the entire coverage area with low inter-beam interference;
- and,
- A number of RRHs distributed over a geographic area transmitting and receiving wherein each RRH contains a plural of antennas, RF transceivers and a synchronization circuit and is connected to a Multi-User Beamformer via a wireless link fronthaul connection provided by a MU-MIMO BS with a large number of antennas at a centralized location which transmits channel information and data wirelessly to the distributed RRHs by beamforming one or more spatial multiplexed streams to each RRH.
1 more element
A method of user grouping to improve MU-MIMO beamforming comprising calculating correlations of the channels of different UEs;
- selecting UEs with low channel correlation into a group, allocating frequency resources to the group of UEs;
- computing precoding and/or detection matrix using channel matrix of the UEs in the group on the allocated frequency resources;
- and performing MU-MIMO beamforming with UEs in the group on the allocated frequency resource.
A method of user grouping for efficient MU-MIMO beamforming computation comprising estimating the delay spreads or coherence bandwidth of the channels of different UEs;
- selecting UEs with similar delay spreads or coherence bandwidth into a group;
- allocating frequency resources to the group of UEs;
- computing precoding and/or detection matrix using channel matrix of the UEs in the group on the allocated frequency resources;
- and performing MU-MIMO beamforming with UEs in the group on the allocated frequency resource.
1 more element
Dependencies are inferred from the claim text.