Control Channel Design for Many-Antenna MU-MIMO Systems

• US 20180338321A1
• Filed: 04/23/2016
• Published: 11/22/2018
• Est. Priority Date: 04/24/2015
• Status: Active Grant

• Current Assignee: Skylark Wl Holdings, LLC
• Original Assignee: Skylark Wireless LLC
• Inventors: Shepard, Clayton Wells, Zhong, Lin, Javed, Abeer, Yu, Hang
• Granted Patent: US 10,455,608 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/046 taking physical layer constraints into account
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26132 using repetition
• CPC Class Codes: H04L 27/2692 with preamble design, i.e. with negotiation of the synchronisation sequence with transmitter or sequence linked to the algorithm used at the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 48/00 Access restriction access security to prevent unauthorised access H04W12/08; Network selection; Access point selection
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 68/02 Arrangements for increasing efficiency of notification or paging channel
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

Disclosed embodiments include methods for control channel design in many-antenna multi-user (MU) multiple-input multiple-output (MIMO) wireless systems. A beacon comprising an identifier of a many-antenna base station is encoded into a base sequence. A plurality of synchronization sequences is generated based on the encoded base sequence and a set of orthogonal beam sequences. The many-antenna base-station transmits, using a plurality of antennas, the plurality of synchronization sequences in a plurality of beam directions associated with the set of orthogonal beam sequences for synchronization and associated with users without knowledge of channel state information (CSI).

Claims

1. A method for wireless communications by a base station (BS), comprising:

encoding a beacon into a base synchronization sequence, the beacon comprising an identifier (ID) of the BS;

generating a plurality of synchronization sequences based on the encoded base synchronization sequence and a set of beamforming weights; and

transmitting, using a plurality of antennas, the plurality of synchronization sequences in a plurality of beam directions associated with the set of beamforming weights.

2. The method of claim 1, wherein transmitting the plurality of synchronization sequences comprises:

transmitting each synchronization sequence followed by transmitting at least one repetition of that synchronization sequence.

3. The method of claim 1, wherein transmitting the plurality of synchronization sequences comprises:

transmitting each synchronization sequence at a beginning of each transmission frame in a different beam direction of the plurality of beam directions.

4. The method of claim 1, further comprising:

allocating at least one uplink slot to a user equipment (UE) for random access;

receiving a pilot from the UE in the at least one allocated uplink slot;

estimating channel state information (CSI) associated with the UE based on the received pilot;

establishing a communication link with the UE based on the CSI; and

conveying control channel information to the UE via the communication link.

5. The method of claim 4, wherein the control channel information comprises at least one of:

a Basic Service Set Identifier (BSSID), a Service Set Identifier (SSID), a modulation rate, gain control information, channel estimation information, or encryption information associated with the BS.

6. The method of claim 1, further comprising:

assigning a unique paging sequence to each user equipment (UE) synchronized and associated with the BS; and

transmitting, using the plurality of antennas, the paging sequence in a set of beam directions until being received by that UE.

7. The method of claim 6, further comprising:

receiving, from the UE, location information associated with the UE, the location information comprises at least one of a physical location of the UE, channel state information (CSI) associated with the UE, information about strengths of one or more of the synchronization sequences received at the UE, or an angle of arrival of at least one of the synchronization sequences received at the UE, and the method further comprises

transmitting the paging sequence in the set of beam directions based on the location information, wherein each beam direction from the set has a finer resolution than each beam direction from the plurality of beam directions.

8. The method of claim 6, further comprising:

receiving an uplink pilot transmitted from the UE upon detection of the paging sequence;

estimating channel state information (CSI) associated with the UE based on the received uplink pilot;

establishing a communication link with the UE based on the estimated CSI.

9. The method of claim 1, further comprising:

transmitting one or more paging sequences unique to one or more user equipments (UEs) served by the BS and a synchronization sequence of the plurality of synchronization sequences in different beam directions of the plurality of beam directions.

10. An apparatus for wireless communications, comprising:

an encoder configured to encode a beacon into a base synchronization sequence, the beacon comprising an identifier (ID) of the apparatus;

a circuit configured to generate a plurality of synchronization sequences based on the encoded base synchronization sequence and a set of beamforming weights; and

a transmitter configured to transmit, using a plurality of antennas, the plurality of synchronization sequences in a plurality of beam directions associated with the set of beamforming weights.

11. A method for wireless communications, comprising

receiving a plurality of synchronization sequences having different signal strengths;

correlating samples of a synchronization sequence from the plurality of synchronization sequences with a set of identification sequences to detect timing of the synchronization sequence; and

decoding, from the synchronization sequence, a beacon having an identifier (ID) of a base station (BS) encoded in the synchronization sequence.

12. The method of claim 11, further comprising:

performing autocorrelation on the samples of the synchronization sequence before the correlation.

13. The method of claim 11, further comprising:

monitoring for at least one synchronization sequence of the plurality of synchronization sequences; and

varying gain settings until detecting a defined number of beacons within the plurality of synchronization sequences.

14. The method of claim 11, further comprising:

upon decoding the beacon with the ID of the BS, transmitting a pilot to the BS in one of slots reserved for random access;

receiving control channel information transmitted from the BS upon reception of the pilot.

15. The method of claim 14, further comprising:

associating with the BS based on the received control channel information.

16. The method of claim 14, further comprising:

selecting to associate with another BS upon reception of the control channel information.

17. The method of claim 11, further comprising:

transmitting location information to the BS, upon decoding the beacon;

receiving a unique paging sequence transmitted from the BS based on the location information;

transmitting, based on the received paging sequence, an uplink pilot in a dedicated random access pilot slot.

18. The method of claim 11, further comprising:

receiving the samples of the synchronization sequence on multiple beamforming streams of a user equipment (UE); and

correlating the samples of the synchronization sequence on each beamforming stream of the UE to decode the beacon.

19. The method of claim 11, further comprising:

detecting the synchronization sequence on an antenna of a user equipment (UE);

computing beamforming weights based on the detected synchronization sequence; and

correlating a subset of the samples of the synchronization sequence on multiple beamforming streams of the UE using the beamforming weights to decode the beacon.

20. An apparatus for wireless communications, comprising

a receiver configured to receive a plurality of synchronization sequences having different signal strengths;

a first circuit configured to correlate samples of a synchronization sequence from the plurality of synchronization sequences with a set of identification sequences to detect timing of the synchronization sequence; and

a second circuit configured to decode, from the synchronization sequence, a beacon having an identifier (ID) of another apparatus encoded in the synchronization sequence.