A radio access node and a method of operating the same

A method of operating a communication device, the method comprising:

• determining a first base key for a first cell in a first group of cells from an identifier for the first group of cells, the first group of cells being supported by a first radio access node;
• using the first base key to determine a first encryption key that is to be used to encrypt communications between the communication device and the first radio access node via the first cell;
• and
• in the event that the communication device is to connect to a second cell in the first group of cells, using the first encryption key to encrypt communications between the communication device and the first radio access node via the second cell.

A first radio access node for use in a communication network, the first radio access node supporting a plurality of cells that are divided into one or more groups of cells, wherein at least a first group of cells comprises more than one cell, the first radio access node comprising:

• memory;
• and
• a processor coupled to the memory, wherein the first radio access node is configured to:
• determine a first base key for a communication device that is to connect to the first radio access node via a first cell in the first group of cells;
• wherein the first base key is determined from an identifier for the first group of cells;
• use the first base key to determine a first encryption key that is to be used to encrypt communications between the communication device and the first radio access node via the first cell;
• and
• use the first encryption key to encrypt communications between the communication device and the first radio access node in the event that the communication device is to connect to the first radio access node via a second cell in the first group of cells.

A communication device, the communication device comprising:

• a processor;
• and
• a memory coupled to the processor, wherein the communication device is configured to:
• determine a first base key for a first cell in a first group of cells from an identifier for the first group of cells, wherein the first group of cells are supported by a first radio access node;
• use the first base key to determine a first encryption key that is to be used to encrypt communications between the communication device and the first radio access node via the first cell;
• and
• use the first encryption key to encrypt communications between the communication device and the first radio access node in the event that the communication device is to connect to a second cell in the first group of cells.