Medium Access Control in LTE-U

• US 10,560,891 B2
• Filed: 09/09/2014
• Issued: 02/11/2020
• Est. Priority Date: 09/09/2014
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Vutukuri, Eswar, Suzuki, Takashi, Anderson, Nicholas William, Cai, Zhijun
• Primary Examiner(s): Kassim, Khaled M
• Assistant Examiner(s): Belete, Berhanu D
• Application Number:
  US14/481,808
• Publication Number:
  US 20160073344A1
• Time in Patent Office: 1,981 Days
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0091 Signaling for the administration of the divided path
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In some implementations, a Medium Access Control (MAC) method for LTE in Unlicensed (LTE-U) includes transmitting at least one of a Clear to Send (CTS) message or a Request to Send (RTS) message on an LTE-U Secondary Cell (SCell) carrier. The at least one of the CTS message or the RTS message may include a duration field. The duration field may indicate a transmission time of a transmission on a packet data shared channel on the LTE-U SCell carrier. An evolved NodeB (eNB) transmits a scheduling grant for the transmission on the packet data shared channel on the LTE-U SCell carrier.

Claims

1. A method, comprising:

receiving, at an evolved Node B (eNB), a long term evolution (LTE) Scheduling Request (SR) transmitted from a User Equipment (UE) on a long term evolution (LTE) in Unlicensed (LTE-U) secondary cell (SCell) carrier;

in response to receiving the LTE SR at the eNB, determining, at the eNB, to grant resources on the LTE-U SCell carrier for an uplink transmission, wherein the determininq to grant resources on the LTE-U SCell carrier comprises measuring a signal level lower than a threshold;

transmitting, from the eNB, at least one of a Clear to Send (CTS) message or a Request to Send (RTS) message on the LTE-U SCell carrier, wherein the at least one of the CTS message or the RTS message includes a duration field, the duration field indicating a time period until an end of a scheduled transmission time, and wherein the at least one of the CTS message or the RTS message is addressed to a Medium Access Control (MAC) address or a pseudo MAC address associated with the evolved Node B (eNB); and

in response to transmitting the at least one of the CTS message or the RTS message, transmitting, from the eNB and on an LTE primary cell (PCell) carrier, a scheduling grant for a transmission on the LTE-U SCell carrier, wherein the LTE PCell carrier is in a licensed frequency spectrum.

2. The method of claim 1, wherein the scheduling grant indicates a Physical Uplink Shared Channel (PUSCH) transmission, further comprising:

receiving, from the UE, a PUSCH subframe during the scheduled transmission time.

3. A method, comprising:

receiving, from an eNB and on a long term evolution (LTE) primary cell (PCell) carrier, an UL grant that indicates a permission for a PUSCH transmission on an LTE in Unlicensed (LTE-U) secondary cell (SCell) carrier during one or more subframes, wherein the LTE PCell carrier is in a licensed frequency spectrum;

determining, at a User Equipment (UE), that the LTE-U SCell carrier is available for transmission during the one or more subframes wherein the determining that the LTE-U SCell carrier is available for transmission during the one or more subframes comprises measuring a signal level lower than a threshold; and

in response to determining at the UE that the LTE-U SCell carrier is available for transmission;

transmitting, from the UE, a CTS message on the LTE-U SCell carrier independent of receiving an RTS, wherein the CTS message includes a duration field, the duration field indicating a time period until an end of the one or more subframes, and the CTS message includes a Medium Access Control (MAC) address or a pseudo MAC address associated with the UE; and

transmitting a PUSCH subframe on the LTE-U SCell carrier during the time period indicated by the duration field.

4. The method of claim 3, wherein the UL grant is received on a Physical Downlink Control Channel (PDCCH).

5. The method of claim 3, wherein the UL grant is a semi-static UL grant received in an RRC message.

6. The method of claim 3, wherein LTE Transmission Time Interval (TTI) bundling is used when transmitting more than one subframes.

7. A base station, comprising:

a memory; and

one or more processors communicatively coupled with the memory and configured to;

receive a long term evolution (LTE) Scheduling Request (SR) transmitted from a User Equipment (UE) on a long term evolution (LTE) in Unlicensed (LTE-U) secondary cell (SCell) carrier;

in response to receiving the LTE SR, determine to grant resources on the LTE-U SCell carrier for an uplink transmission, wherein the determination to qrant resources on the LTE-U SCell carrier comprises measuring a signal level lower than a threshold;

transmit at least one of a Clear to Send (CTS) message or a Request to Send (RTS) message on the LTE-U SCell carrier, wherein the at least one of the CTS message or the RTS message includes a duration field, the duration field indicating a time period until an end of a scheduled transmission time, and wherein the at least one of the CTS message or the RTS message is addressed to a Medium Access Control (MAC) address or a pseudo MAC address associated with an evolved Node B (eNB); and

in response to transmitting the at least one of the CTS message or the RTS message, transmit, from the base station and on an LTE primary cell (PCell) carrier, a scheduling grant for a transmission on the LTE-U SCell carrier, wherein the LTE PCell carrier is in a licensed frequency spectrum.

8. The base station of claim 7, wherein the scheduling grant indicates a Physical Uplink Shared Channel (PUSCH) transmission, and the one or more processors are further configured to:

receive, from the UE, a PUSCH subframe during the scheduled transmission time.

9. A user equipment (UE), comprising:

a memory; and

one or more processors communicatively coupled with the memory and configured to;

receive, from an eNB and on a long term evolution (LTE) primary cell (PCell) carrier, an UL grant that indicates a permission for a PUSCH transmission on an LTE in Unlicensed (LTE-U) secondary cell (SCell) carrier during one or more subframes, wherein the LTE PCell carrier is in a licensed frequency spectrum;

determine, at the UE, that the LTE-U SCell carrier is available for transmission during the one or more subframes, wherein the determination that the LTE-U SCell carrier is available for transmission during the one or more subframes comprises measuring a signal level lower than a threshold; and

in response to determining at the UE that the LTE-U SCell carrier is available for transmission;

transmit from the UE, a CTS message on the LTE-U SCell carrier independent of receiving an RTS, wherein the CTS message includes a duration field, the duration field indicating a time period until an end of the one or more subframes, and the CTS message includes a Medium Access Control (MAC) address or a pseudo MAC address associated with the UE; and

transmit a PUSCH subframe on the LTE-U SCell carrier during the time period indicated by the duration field.

10. The UE of claim 9, wherein the UL grant is received on a Physical Downlink Control Channel (PDCCH).

11. The UE of claim 9, wherein the UL grant is a semi-static UL grant received in an RRC message.

12. The UE of claim 9, wherein LTE Transmission Time Interval (TTI) bundling is used when transmitting more than one subframes.