Preventing misuse of random access procedure in wireless communication system
View Patent ↗A method for preventing misuse of a random access procedure including transmitting a random access preamble, receiving a random access response message which includes a random access response that is scrambled using the identity of the random access preamble transmitted by the mobile station, checking that the random access response is in response to the random access preamble transmitted by the mobile station, and decoding the random access response.
1. A mobile station configured to prevent misuse of a random access procedure, the mobile station comprising:
a transceiver coupled to a controller,
the controller configured to cause the transceiver to transmit and receive,
a random access response received by the mobile station is scrambled using an identity of a random access preamble transmitted by the mobile station;
the controller further configured to check that the random access response is in response to the random access preamble transmitted by the mobile station and to decode the random access response,
wherein the controller is configured to check by de-scrambling a verification code to obtain a de-scrambled verification code, wherein the verification code corresponds to the random access response, and by determining that the descrambled verification code is correct,
wherein the controller is configured to determine that the de-scrambled verification code is correct by de-scrambling the random access response to obtain the descrambled random access response, computing a function of the de-scrambled random access response, and determining that the de-scrambled verification code is equal to the computed function of the de-scrambled random access response, and
wherein the random access response is descrambled to obtain the descrambled random access response by applying an exclusive-or operation between a bit sequence representing the random access response and a bit sequence constructed by repeated concatenation of a bit sequence representing the identity of the random access preamble.
2. A mobile station configured to prevent misuse of a random access procedure, the mobile station comprising:
a transceiver coupled to a controller,
the controller configured to cause the transceiver to transmit and receive,
a random access response received by the mobile station is scrambled using an identity of a random access preamble transmitted by the mobile station;
the controller further configured to check that the random access response is in response to the random access preamble transmitted by the mobile station and to decode the random access response,
wherein the controller is configured to check by de-scrambling a verification code to obtain a de-scrambled verification code, wherein the verification code corresponds to the random access response, and by determining that the descrambled verification code is correct, and
wherein the verification code is de-scrambled to obtain the de-scrambled verification code by applying an exclusive-or operation between the verification code and the identity of the random access preamble.
3. A mobile station configured to prevent misuse of a random access procedure, the mobile station comprising:
a transceiver coupled to a controller,
the controller configured to cause the transceiver to transmit and receive,
a random access response received by the mobile station is scrambled using an identity of a random access preamble transmitted by the mobile station;
the controller further configured to check that the random access response is in response to the random access preamble transmitted by the mobile station and to decode the random access response,
wherein the random access response includes at least one scrambled random access preamble identity,
wherein the random access response message includes at least one resource allocation grant corresponding to the at least one scrambled random access preamble identity, wherein the controller is configured to determine a resource to use for transmission of a message by applying an offset to the resource allocation grant, and
wherein the offset is derived from the identity of the random access preamble transmitted by the mobile station.
4. A base station configured to prevent misuse of a random access procedure, comprising:
a transceiver coupled to a controller,
the controller configured to construct a random access response in response to a random access preamble received by the transceiver;
the controller configured to scramble the random access response using an identity of the random access preamble before transmitting, from the base station, a random access response message that includes the scrambled random access response,
wherein the random access response message further includes a verification code corresponding to the random access response,
wherein the verification code is obtained by scrambling a result of computing a function of the random access response using the identity of the received random access preamble, and
wherein the scrambling is an exclusive-or operation between the result of computing the function of the random access response and the identity of the received random access preamble.
5. A base station configured to prevent misuse of a random access procedure, comprising:
a transceiver coupled to a controller,
the controller configured to construct a random access response in response to a random access preamble received by the transceiver;
the controller configured to scramble the random access response using an identity of the random access preamble before transmitting, from the base station, a random access response message that includes the scrambled random access response,
wherein the scrambling is an exclusive-or operation between the random access response and a bit sequence obtained by repeated concatenation of the bit sequence representing the identity of the received random access preamble.