| CPC H04W 12/03 (2021.01) [H04W 8/005 (2013.01); H04W 12/06 (2013.01); H04W 76/10 (2018.02)] | 33 Claims |
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1. A cellular communication system (CCS) comprising a radio access network (RAN), multiple cellular base stations (BS) and a core network (CN),
the cellular communication system providing a cellular network that supports indirect connections,
each indirect connection providing data transfer between a mobile device and the cellular communication system via at least one relay device being a mobile device arranged for communication with the radio access network and capable of supporting the indirect connection,
the cellular communication system further comprising at least one network relay entity arranged to provide a Network Relay Function (NRF) for managing the indirect connections,
the mobile device comprising:
a connection processor arranged for managing connections to the cellular network, the connection processor providing a relay function for managing at least one indirect connection,
the relay function being arranged to at least
send, as part of a setup procedure, a request message (M) to at least one relay device (UEx), the request message including a Relay Service Code (RSC1) and an encrypted identifier of the at least one relay device (UEx), and further containing an encrypted identifier of the mobile device;
receive a response message (M′) from the at least one relay device (UEx), the response message including an encrypted Relay Service Code (RSC2);
decrypt the encrypted Relay Service Code (RSC2) and insert the decrypted Relay Service Code (RSC2′) instead of RSC1 in subsequent discovery and connection setup messages, whereby RSC2′ is associated with the same set of PDU session attributes as RSC1;
the relay device comprising:
a communication unit arranged for communication in the cellular network, and,
a relay processor arranged for managing the communication in the cellular network and for managing an indirect connection between the mobile device and the cellular network, the relay processor being arranged:
to receive the request message (M) from the mobile device;
after receiving request message (M), to send a transfer request message (N) to the cellular communication system in dependence of the request message (M), the transfer request message (M′) including the Relay Service Code RSC1 and at least one of the encrypted identifiers received from the mobile device in request message (M);
to receive a transfer response message (N′) from the cellular communication system, the transfer response message (N′) containing an encrypted Relay Service Code (RSC2);
after receiving the transfer response message (N′), to send a response message (M) to the mobile device in dependence of the transfer response message and containing the encrypted Relay Service Code (RSC2);
the Network Relay Function being arranged:
to receive at least one transfer request message (N) from the relay device, the transfer request message (N) including a Relay Service Code (RSC1) and at least one of the encrypted identifiers of the mobile device and the encrypted identifier of the relay device;
to determine a different Relay Service Code (RSC2′) to be used instead of the Relay Service Code (RSC1) received in the transfer request message (N); to encrypt the different Relay Service Code (RSC2′) using a key that allows it to be decrypted by the mobile device but not the relay device, resulting in an encrypted Relay Service Code (RSC2);
to send a transfer response message (N′) including the encrypted Relay Service Code (RSC2) to the relay device.
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