Dynamic random access resource size configuration and selection

A non-transitory computer-readable medium storing a computer program that, when executed by processing circuitry of a wireless device configured for operation in a wireless network, configures the wireless device to:

• receive information from a radio network node comprised in a cell of the wireless network, wherein the received information indicates random access resources of different sizes configured for use in the cell of said wireless network;
• select, for use in transmitting a random access message for the radio network node, a smallest-sized one of said random access resources calculated to satisfy a target uplink received energy at the radio network node, in view of a transmit power limit of the wireless device and an estimate of path loss between the wireless device and the radio network node;
• and
• transmit the random access message using the selected random access resource.

A wireless device configured for operation in a wireless network and comprising:

• a network communication transceiver configured to communicate with a radio network node in a cell of said wireless network,
• a processor;
• and
• a memory storing computer program code which, when run in said processor, causes the wireless device to:
• receive information from said radio network node using said network communication transceiver, wherein the received information indicates random access resources of different sizes configured for use in the cell;
• select, for use in transmitting a random access message for the radio network node, a smallest-sized one of said random access resources that satisfies a target uplink received energy at the radio network node, in view of a transmit power limit of the wireless device and an estimate of path loss between the wireless device and the radio network node;
• and
• transmit the random access message using the selected random access resource.

A radio network node configured for operation in a cell of a wireless network, said radio network node comprising:

• a processor;
• and
• a memory storing computer program code which, when run in the processor, causes the radio network node to:
• configure random access resources of different sizes for use in a cell associated with the radio network node according to an arrangement whereby random access resources having dissimilar sizes do not overlap in time or frequency, the different sizes corresponding to different ranges of expected uplink received power at the radio network node;
• and
• transmit configuration information indicating the random access resources, thereby enabling one or more wireless devices operating in the cell to transmit random access messages for the radio network node using selected ones of the random access resources.

A method at a wireless device configured for operation in a wireless network, the method comprising:

• with respect to two or more differently-sized random access resources configured for use in attempting random access towards a radio network node of the wireless network,
• selecting the smallest-sized one of the two or more random access resources that is calculated to satisfy a target uplink received energy at the radio network node, in view of a transmit power limit of the wireless device and an estimate of path loss between the wireless device and the radio network node;
• and
• transmitting a random access message using the selected random access resource.