Bandwidth part switching methods and apparatus for wireless devices

A method of data transmission, comprising:

• receiving, by a user equipment (UE), a configuration message indicating one or more frequency bands for transmitting a radio signal;
• determining, by the UE, a first frequency band from among the one or more frequency bands;
• performing by the UE, a listen before talk (LBT) operation on the first frequency band;
• switching, by the UE, the first frequency band to a second frequency band different from the first frequency band in a case that the LBT operation fails, the second frequency band having a first portion for transmitting a random access preamble;
• and
• transmitting, by the UE, the random access preamble in the first portion of the second frequency band in a case that the first frequency band is switched to the second frequency band,
• wherein the switching, by the UE, the first frequency band to the second frequency band different from the first frequency band in a case that the LBT operation fails comprises determining whether the second frequency band has the first portion for transmitting the random access preamble, and
• wherein the configuration message includes information that specifies a bandwidth and a location of each of the one or more frequency bands and is received via a Radio Resource Control (RRC) layer signaling.

A method of data transmission, comprising:

• determining, by a base station, one or more frequency bands;
• transmitting, by the base station via a Radio Resource Control (RRC) layer signaling, a configuration message including information that specifies a bandwidth and a location of each of the one or more frequency bands for receiving a radio signal by the base station;
• monitoring, by the base station, at least a first frequency band and a second frequency band among the one or more frequency bands, the second frequency band having a first portion for receiving a random access preamble;
• and
• receiving, by the base station, the random access preamble from a user equipment (UE) in the second frequency band in a case that the first frequency band is switched to the second frequency band by the UE,
• wherein the second frequency band is determined by the UE as having the first portion for transmitting the random access preamble and is the one to which the UE switches from the first frequency band in a case that a listen before talk (LBT) operation performed by the UE on the first frequency band fails.

A user equipment (UE), comprising:

• a transceiver configured to receive a configuration message indicating one or more frequency bands for transmitting a radio signal via a Radio Resource Control (RRC) layer signaling, the configuration message including information that specifies a bandwidth and a location of each of the one or more frequency bands;
• and
• a processor in communication with the transceiver and configured to:
• determine a first frequency band from among the one or more frequency bands;
• perform a listen before talk (LBT) operation on the first frequency band;
• determine whether a second frequency band different from the first frequency band has a first portion for transmitting a random access preamble;
• and
• switch the first frequency band to the second frequency band different from the first frequency band in a case that the LBT operation fails, based on a determination that the second frequency band has the first portion for transmitting the random access preamble,
• wherein the transceiver is further configured to transmit the random access preamble in the first portion of the second frequency band in a case that the first frequency band is switched to the second frequency band.

A base station, comprising:

• a transceiver configured to transmit a configuration message indicating one or more frequency bands for transmitting a radio signal via a Radio Resource Control (RRC) layer signaling, the configuration message including information that specifies a bandwidth and a location of each of the one or more frequency bands;
• and
• a processor in communication with the transceiver and configured to:
• determine the one or more frequency bands;
• and
• monitor at least a first frequency band and a second frequency band among the one or more frequency bands, the second frequency band having a first portion for receiving a random access preamble,
• wherein the transceiver is further configured to receive the random access preamble from a user equipment (UE) in the second frequency band in a case that the first frequency band is switched to the second frequency band by the UE, and
• wherein the second frequency band is determined by the UE as having the first portion for transmitting the random access preamble and is the one to which the UE switches from the first frequency band in a case that a listen before talk (LBT) operation performed by the UE on the first frequency band fails.