Preamble allocation method and random access method in mobile communication system
The present invention relates to a preamble allocation method and a random access method in a mobile communication system. In the present invention, one among preamble resources is allocated to specific mobile stations in advance, before random access. The mobile stations request random access by transmitting a preamble based on the pre-allocated preamble resource to a base station. It is therefore possible to prevent collision caused by the fact that other mobile stations transmit the same preamble.
1. A method for a base station to allocate a preamble to a mobile station, comprising:
classifying preamble resources into a contention-based group and a reserved allocation group to generate classification information for the preamble resources;
transmitting the classification information to the mobile station;
selecting one preamble index belonging to the reserved allocation group; and
sending, to the mobile station, the selected preamble index belonging to the reserved allocation group;
wherein the mobile station requests random access based on a corresponding preamble generated from the received selected preamble index.
2. The method of claim 1 , wherein sending the one preamble index comprises:
sending, to the mobile station, the one preamble index via downlink data generating indication information.
3. The method of claim 1 , wherein sending the one preamble index comprises:
sending, to the mobile station, the one preamble index via a handover-related message.
4. The method of claim 1 , further comprising:
receiving a preamble corresponding to the one preamble index; and
transmitting a random access response message to the mobile station.
5. The method of claim 4 , wherein the random access response message includes radio resource allocation information.
6. The method of claim 5 , wherein the random access response message further includes information on the preamble transmitted by the mobile station.
7. The method of claim 6 , wherein the random access response message further includes at least one of downlink resource allocation information, scheduling identifier, and information on whether the base station successfully received the preamble based on the one preamble index informed by the base station.
8. The method of claim 1 , wherein a preamble consists of a first part representing a random property and a second part representing additional information,
wherein classifying the preamble resources comprises:
classifying the preamble resources into the contention-based group, the reserved allocation group, and an additional information group.
9. The method of claim 8 , wherein the additional information is one of the following:
CQI (channel quality indicator) information representing whether a corresponding channel has greater quality than a predetermined value in a service area of the base station;
information representing that the mobile station accesses through a handover process from a neighboring base station; and
information representing that the mobile station does not perform initial access but maintains a connection with the base station.
10. A method for a base station to perform a random access procedure with a mobile station, comprising:
classifying a plurality of random access preambles into a contention based random access preamble group and a non-contention based random access preamble group to generate system information including classification information which enables to classify the plurality of random access preambles;
broadcasting the system information;
selecting one random access preamble index corresponding to one random access preamble belonging to the non-contention based random access preamble group;
allocating, to the mobile station, the corresponding one random access preamble in association with the selected random access preamble index;
sending, to the mobile station the selected random access preamble index; and
in response to receiving, from the mobile station, a random access request on the basis of the corresponding one random access preamble generated from the selected random access preamble index:
providing a random access response to the mobile station.
11. The method of claim 10 , wherein allocating the one random access preamble comprises:
allocating, to the mobile station, the one random access preamble belonging to the non-contention based random access preamble group when downlink data is generated or the mobile station performs a handover.
12. The method of claim 10 , further comprising:
receiving the allocated random access preamble; and
transmitting a random access response to the mobile station.
13. The method of claim 12 , wherein the random access response includes radio resource allocation information and information on the allocated random access preamble.
14. A method for a base station to perform a random access procedure with a mobile station, comprising:
classifying a plurality of random access preambles into a contention based random access preamble group and a non-contention based random access preamble group to generate system information including classification information which enables to classify the plurality of random access preambles;
broadcasting the system information;
selecting one random access preamble index corresponding to one random access preamble belonging to the non-contention based random access preamble group;
allocating, to the mobile station, the corresponding one random access preamble in association with the selected random access preamble index;
sending, to the mobile station the selected random access preamble index; and
in response to receiving, from the mobile station, a random access request on the basis of the corresponding one random access preamble generated from the selected random access preamble index:
receiving the allocated random access preamble to provide a random access response to the mobile station.
15. A random access method of a mobile station, comprising:
receiving, from a base station, system information including information which enables to classify a plurality of random access preambles into a contention based random access preamble group and a non-contention based random access preamble group;
receiving, from the base station, a selected random access preamble index indicating allocation information for one corresponding random preamble belonging to the non-contention based random access preamble group;
when the mobile station receives, from the base station, the selected random access preamble index, generating the corresponding random preamble using the selected random access preamble index and transmitting a random access request including the corresponding random access preamble to the base station; and
receiving a random access response from the base station.
16. A random access method of claim 15 , when the mobile station does not receive allocation information for one random access preamble belonging to the non-contention based random access preamble group, transmitting one random access preamble belonging to the contention based random access preamble group to the base station.
17. The method of claim 15 , wherein receiving the selected random access preamble index includes receiving the selected random access preamble index via downlink data generating indication information.
18. The method of claim 15 , wherein receiving the selected random access preamble index includes receiving the selected random access preamble index via a handover-related message.
19. A random access method of a mobile station, comprising:
receiving, from a base station, system information including information which enables to classify a plurality of random access preambles into a contention based random access preamble group and a non-contention based random access preamble group;
receiving, from the base station, a selected random access preamble index indicating allocation information for one corresponding random preamble belonging to the non-contention based random access preamble group;
when the mobile station receives, from the base station, the selected random access preamble index, generating the corresponding random preamble using the selected random access preamble index and transmitting a random access request including the corresponding random access preamble to the base station;
when the mobile station does not receive random access preamble index indicating allocation information for random access preamble belonging to the non-contention based random access preamble group, transmitting a contention-based random access request including one random access preamble belonging to a contention based random access preamble group to the base station; and
receiving a random access response from the base station.
20. The method of claim 19 , wherein receiving the selected random access preamble index includes receiving the selected random access preamble index via downlink data generating indication information.
21. The method of claim 19 , wherein receiving the selected random access preamble index includes receiving the selected random access preamble index via a handover related message.