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US 10,952,172 B2Granted
Time and frequency synchronization
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsHavish Koorapaty, Mattias Frenne, Daniel Larsson, Jiann-Ching Guey, Jung-Fu Cheng
Life of this patent
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Abstract
The scheduling flexibility of CSI reference signals enables time and frequency synchronization using multiple non-zero CSI-RSs transmitted in the same subframe, or using CSI-RSs transmitted in the same subframe with other synchronization signals. Also, multiple synchronization signals may be scheduled in the same subframe to enable fine time and frequency synchronization without cell-specific reference signals.
Claims15
A method of transmitting reference signals for synchronization in an Orthogonal Frequency Division Multiplexing (OFDM) system, said method comprising:
- transmitting a first channel state information (CSI) reference signal in a first slot of a plurality of subframes in accordance with a first configuration of transmission resources, wherein the first configuration of transmission resources defines a first allocation of time and frequency resources for the first CSI reference signal;
- transmitting a second CSI reference signal in a second slot of one or more of the plurality of subframes in accordance with a second configuration of transmission resources, wherein the second configuration of transmission resources defines a second allocation of time and frequency resources for the second CSI reference signal, and
- wherein transmitting the first CSI reference signal in accordance with the first configuration and transmitting the second CSI reference signals in accordance with the second configuration comprises transmitting the first and second CSI reference signals in both the first slot and the second slot of at least a first subframe of the plurality of subframes,
- wherein the same antenna port is used for transmission of the first and second CSI reference signals if the first and second CSI reference signals are for synchronization assistance and different antenna ports are used for transmission if the first and second CSI reference signals are not for synchronization assistance.
1 more element
A method of synchronization in an Orthogonal Frequency Division Multiplexing (OFDM) system, said method comprising:
- receiving a first channel state information (CSI) reference signal in a first slot of a plurality of subframes in accordance with a first configuration of transmission resources, wherein the first configuration of transmission resources defines a first allocation of time and frequency resources for the first CSI reference signal;
- receiving a second CSI reference signal in a second slot of one or more of the plurality of subframes in accordance with a second configuration of transmission resources different from the first configuration, wherein the second configuration of transmission resources defines a second allocation of time and frequency resources for the second CSI reference signal;
- wherein receiving the first CSI reference signal in accordance with the first configuration and receiving the second CSI reference signal in accordance with the second configuration comprises receiving CSI reference signals during both the first slot and the second slot of at least a first subframe of the plurality of subframes;
- and synchronizing with the OFDM system using the first and second CSI reference signals received during the first subframe if the first and second CSI reference signals are received on the same antenna port during both the first slot and the second slot of the at least first subframe.
1 more element
A user terminal in an Orthogonal Frequency Division Multiplexing (OFDM) system, said user terminal comprising:
- a transceiver circuit configured to communicate with a base station over a wireless communicate channel;
- and a control circuit for synchronizing with the OFDM system, said control circuit being configured to:
- receive a first channel state information (CSI) reference signal in a first slot of a plurality of subframes in accordance with a first configuration of transmission resources, wherein the first configuration of transmission resources defines a first allocation of time and frequency resources for the first CSI reference signal;
- receive a second CSI reference signal in a second slot of one or more of the plurality of subframes in accordance with a second configuration of transmission resources different from the first configuration, wherein the second configuration of transmission resources defines a second allocation of time and frequency resources for the second CSI reference signal;
- and wherein receiving the first CSI reference signal in accordance with the first configuration and receiving the second CSI reference signal in accordance with the second configuration comprises receiving CSI reference signals during both the first slot and the second slot of at least a first subframe of the plurality of subframes;
- synchronize with the OFDM system using the first and second CSI reference signals if the first and second CSI reference signals are received on the same antenna port during both the first slot and the second slot of the at least first subframe.
3 more elements
Dependencies are inferred from the claim text.