Random access channel preamble selection
The present invention provides a method of selecting a random access preamble in a radio communication system operable at least on a physical layer and a medium access control layer. Random access preambles are divided into at least two groups, the groups depending on at least one of the following: radio conditions and a size of a message to be transmitted by user equipment. The method comprising: (a) the medium access control layer selecting one of the preamble groups; (b) the medium access control layer randomly selecting one random access preamble within the selected group; (c) the medium access control layer signalling the selected random access preamble to the physical layer; and (d) the physical layer generating and transmitting the generated random access preamble.
1. A method of performing a random access procedure by a User Equipment (UE) in a radio communication system, the method comprising:
a Layer 2 (L2) of the UE selecting one of preamble groups according to at least radio conditions or a size of a message to be transmitted;
the L2 of the UE randomly selecting a random access preamble within the selected preamble group;
the L2 of the UE indicating a preamble index to a Layer 1 (L1) of the UE, the preamble index corresponding to the selected random access preamble;
the L1 of the UE selecting a random access preamble sequence using the preamble index; and
the L1 of the UE transmitting the selected random access preamble sequence.
2. The method of claim 1 , wherein the L2 is a Medium Access Control (MAC) layer, and the L1 is a Physical (PHY) layer.
3. The method of claim 1 , further comprising the L2 of the UE indicating at least one of following parameters to the L1 of the UE:
a logical root sequence index of the selected random access preamble,
a preamble start position within a selected logical root sequence index of the selected random access preamble, and
a cyclic shift describing a correlation size of a Zadoff-Chu sequence.
4. The method of claim 3 , further comprising the L1 of the UE mapping the selected logical root sequence index to a physical root sequence index.
5. The method of claim 1 , further comprising the L1 of the UE mapping the preamble index to at least one of a physical root sequence index, a preamble start position within a selected logical root sequence index, and a cyclic shift describing a correlation size of a Zadoff-Chu sequence.
6. The method of claim 1 , wherein the random access procedure is a non-synchronized random access procedure.
7. A User Equipment (UE) configured to perform a random access procedure in a radio communication system, the UE comprising:
a controller configured to:
control a Layer 2 (L2) to select one of preamble groups according to at least a radio condition or a size of a message to be transmitted;
control the L2 to randomly select one a random access preamble within the selected preamble group;
control the L2 to indicate a preamble index to a Layer (L1), the preamble index corresponding to the selected random access preamble;
control the L1 to select a random access preamble sequence using the preamble index; and
control the L1 to transmit the selected random access preamble sequence.
8. The UE of claim 7 , wherein the L2 is a Medium Access Control (MAC) layer, and the L1 is a Physical (PHY) layer.
9. The UE of claim 7 , wherein the controller is further configured to control the L2 to indicate at least one of following parameters to the L1:
a logical root sequence index of the selected random access preamble,
a preamble start position within a selected logical root sequence index of the selected random access preamble, and
a cyclic shift describing a correlation size of a Zadoff-Chu sequence.
10. The UE of claim 9 , wherein the controller is further configured to control the L1 to map the selected logical root sequence index to a physical root sequence index.
11. The UE of claim 7 , wherein the controller is further configured to control the L1 to map the preamble index to at least one of a physical root sequence index, a preamble start position within a selected logical root sequence index, and a cyclic shift describing a correlation size of a Zadoff-Chu sequence.
12. The UE of claim 7 , wherein the random access procedure is a non-synchronized random access procedure.