Terminal apparatus, base station apparatus, and communication method

A base station apparatus, comprising:

• a transmitter configured to transmit a Physical Downlink Control CHannel (PDCCH) order for initiating a random access procedure, wherein the PDCCH order includes a first piece of information, and the first piece of information is a preamble index used for indicating a random access preamble;
• and
• a receiver configured to receive the random access preamble by using a Physical Random Access CHannel (PRACH),
• wherein transmit power for transmitting the random access preamble is set by a terminal apparatus based on a transmission counter,
• the PDCCH order causes the terminal apparatus to determine, at least based on whether or not the preamble index included in the PDCCH order is a specific preamble index, whether or not the transmission power is set based on a calculation in which the transmission counter is incremented,
• and
• the PDCCH order includes a second piece of information used for selecting a resource of the PRACH.

A communication method to be used for a terminal apparatus, the method comprising the steps of:

• initiating a random access procedure based on a Physical Downlink Control CHannel (PDCCH) order, wherein the PDCCH order includes a first piece of information, and the first piece of information is a preamble index used for indicating a random access preamble;
• transmitting the random access preamble by using a Physical Random Access CHannel (PRACH);
• setting transmit power for transmitting the random access preamble based on a transmission counter;
• and
• determining whether or not the transmission power is set based on a calculation in which the transmission counter is incremented, at least based on whether or not the preamble index included in the PDCCH order is a specific preamble index,
• wherein the PDCCH order includes a second piece of information used for selecting a resource of the PRACH.

A communication method to be used for a base station apparatus, the method comprising the steps of:

• transmitting a Physical Downlink Control CHannel (PDCCH) order for initiating a random access procedure, wherein the PDCCH order includes a first piece of information, and the first piece of information is a preamble index used for indicating a random access preamble;
• and
• receiving the random access preamble by using a Physical Random Access CHannel (PRACH),
• wherein transmit power for transmitting the random access preamble is set by a terminal apparatus based on a transmission counter,
• the PDCCH order causes the terminal apparatus to determine, at least based on whether or not the preamble index included in the PDCCH order is a specific preamble index, whether or not the transmission power is set based on a calculation in which the transmission counter is incremented,
• and
• the PDCCH order includes a second piece of information used for selecting a resource of the PRACH.