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US 12,004,107 B2Granted
Time and frequency synchronization
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsHavish Koorapaty, Mattias Frenne, Daniel Larsson, Jiann-Ching Guey, Jung-Fu Cheng
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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.
Claims20
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 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 from the same antenna port in both the first slot and the second slot of at least a first subframe of the plurality of subframes, and
- wherein the same antenna port is used for transmission of the first and second CSI reference signals to ensure a user terminal in the OFDM system can utilize the first and second CSI reference signals for synchronization assistance.
1 more element
A base station in an Orthogonal Frequency Division Multiplexing (OFDM) system, said base station comprising:
- a transceiver circuit configured to communicate with a user terminal over a wireless communicate channel;
- and
- a control circuit providing reference signals for transmission to the user terminal via the transceiver circuit, said control circuit being configured to:
- transmit a first channel state information (CSI) reference signal in a first slot of one or more subframes;
- transmit a second CSI reference signal in a second slot of one or more of the same subframes;
- and
- transmit the first and second CSI reference signals from the same antenna port to ensure the user terminal in the OFDM system can utilize the first and second CSI reference signals for synchronization assistance.
4 more elements
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 difference 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 transmitted on the same antenna port 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.
2 more elements
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 difference 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;
- receive the first and second CSI reference signals on the same antenna port in at least one of the plurality of subframes;
- and
- synchronize with the OFDM system using the first and second CSI reference signals received on the same antenna port in the at least one subframe.
5 more elements
Dependencies are inferred from the claim text.