Apparatus and method for allocating radio network temporary identifier for random access in a mobile communication system
An apparatus and method for allocating Radio Network Temporary Identifiers (RNTIs) for random access in a mobile communication system are provided. An Evolved Node B (ENB) determines the number of RNTIs allocated to at least one User Equipment (UE) that transmitted a random access preamble, determines an average number of random access preambles received during a Transmission Time Interval (TTI), and sets a timer based on the number of allocated RNTIs and the average number of random access preambles. If a cell identifier corresponding to a first UE is not received from an upper layer before expiration of the timer, the ENB releases the RNTI allocated to the first UE, and allocates the released RNTI to a second UE different from the first UE.
1. A method for allocating Radio Network Temporary Identifiers (RNTIs) for random access by an Evolved Node B (ENB) in a mobile communication system, the method comprising:
determining, by the ENB, a number of RNTIs allocated to at least one User Equipment (UE) that transmitted a random access preamble;
determining, by the ENB, an average number of random access preambles received during a Transmission Time Interval (TTI);
setting, by the ENB, a timer based on the number of allocated RNTIs and the average number of random access preambles;
releasing, by the ENB, an RNTI allocated to a first UE if a cell identifier corresponding to the first UE is not received from an upper layer before expiration of the timer; and
allocating, by the ENB, the released RNTI to a second UE different from the first UE.
2. The method of claim 1 , wherein the setting of the timer comprises setting, by the ENB, the timer using a weight that is determined according to a number of UEs requesting call setup using an RNTI allocated to the at least one UE.
3. The method of claim 1 , wherein the setting of the timer comprises setting, by the ENB, the timer using a weight that is determined according to the number of RNTIs allocated to the at least one UE.
4. The method of claim 1 , wherein the setting of the timer comprises setting, by the ENB, the timer in inverse proportion to at least one of the number of RNTIs allocated to the at least one UE and the average number of random access preambles.
5. The method of claim 1 , further comprising:
determining, by the ENB, a number of available RNTIs,
wherein the setting of the timer comprises setting, by the ENB, the timer based on the number of allocated RNTIs, the average number of random access preambles, and the number of available RNTIs.
6. The method of claim 5 , wherein the setting of the timer comprises setting, by the ENB, the timer using a weight that is determined according to the number of available RNTIs.
7. The method of claim 5 , wherein the setting of the timer comprises setting, by the ENB, the timer in proportion to the number of available RNTIs.
8. The method of claim 1 , wherein the determining of the number of RNTIs allocated to the at least one UE comprises determining, the ENB, the number of RNTIs that are allocated to the at least one UE and not in use, and the number of RNTIs that are allocated to the at least one UE and in use.
9. The method of claim 1 , further comprising decreasing, by the ENB, the setting of the timer if at least one of the number of RNTIs allocated to the at least one UE is greater than a first threshold and the number of random access preambles received for the TTI is greater than a second threshold.
10. The method of claim 1 , wherein the setting of the timer comprises setting, by the ENB, the timer using the following equation,
Timeout
=
K
×
α
×
Number
of
Available
RNTIs
β
×
Number
of
Allocated
RNTIs
+
τ
×
Average
Number
of
RACHs
(
1
TTI
)
×
Max_Timeout
where Number of Allocated RNTIs represents the number of RNTIs allocated to the at least one UE, Average Number of RACHs represents the average number of random access preambles received for one TTI, Number of Available RNTIs represents the number of available RNTIs, Max_Timeout represents the maximum use time for which the RNTI allocated to the at least one UE can be used, K represents an arbitrary number, α represents a weight for the available RNTIs, β represents a weight for the RNTI allocated to the at least one UE, and τ represents a weight for the average number of Random Access Channels (RACHs).
11. An Evolved Node B (ENB) apparatus for allocating Radio Network Temporary Identifiers (RNTIs) for random access in a mobile communication system, the apparatus comprising:
an RNTI allocator for determining a number of RNTIs allocated to at least one User Equipment (UE) that transmitted a random access preamble, for determining an average number of random access preambles received for a Transmission Time Interval (TTI), for setting a timer based on the number of allocated RNTIs and the average number of random access preambles, for releasing an RNTI allocated to a first UE if a cell identifier corresponding to the first UE is not received from an upper layer before expiration of the timer, and for allocating the released RNTI to a second UE different from the first UE; and
the timer for running for a time set by the RNTI allocator.
12. The apparatus of claim 11 , wherein the RNTI allocator sets the timer using a weight that is determined according to a number of UEs requesting call setup using an RNTI allocated to the at least one UE.
13. The apparatus of claim 11 , wherein the RNTI allocator sets the timer using a weight that is determined according to the number of RNTIs allocated to the at least one UE.
14. The apparatus of claim 11 , wherein the RNTI allocator sets the timer in inverse proportion to at least one of the number of RNTIs allocated to the at least one UE and the average number of random access preambles.
15. The apparatus of claim 11 , wherein the RNTI allocator determines a number of available RNTIs, and sets the timer based on the number of allocated RNTIs, the average number of random access preambles, and the number of available RNTIs.
16. The apparatus of claim 15 , wherein the RNTI allocator sets the timer using a weight that is determined according to the number of available RNTIs.
17. The apparatus of claim 15 , wherein the RNTI allocator sets the timer in proportion to the number of available RNTIs.
18. The apparatus of claim 11 , wherein the RNTI allocator determines the number of RNTIs allocated to the at least one UE and not in use, and the number of RNTIs that are allocated to the at least one UE and in use.
19. The apparatus of claim 11 , wherein the RNTI allocator decreases the setting of the timer if at least one of the number of RNTIs allocated to the at least one UE is greater than a first threshold and the number of random access preambles received for the TTI is greater than a second threshold.
20. The apparatus of claim 11 , wherein the RNTI allocator sets the timer using the following equation,
Timeout
=
K
×
α
×
Number
of
Available
RNTIs
β
×
Number
of
Allocated
RNTIs
+
τ
×
Average
Number
of
RACHs
(
1
TTI
)
×
Max_Timeout
where Number of Allocated RNTIs represents the number of RNTIs allocated to the at least one UE, Average Number of RACHs represents the average number of random access preambles received for one TTI, Number of Available RNTIs represents the number of available RNTIs, Max_Timeout represents the maximum use time for which the RNTI allocated to the at least one UE can be used, K represents an arbitrary number, α represents a weight for the available RNTIs, β represents a weight for the RNTI allocated to the at least one UE, and τ represents a weight for the average number of Random Access Channels (RACHs).