SYSTEM AND METHOD TO ADJUST PUCCH CAPACITY
Systems and methods to allocate PUCCH resources such as Scheduling Request (SR) and Channel State Information (CSI) to RRC-Connected UEs in the 4G and 5G radio access network (RAN).
1 : A system comprising:
a Base Station (BS) comprising
an Incoming-Traffic Tracker configured to calculate an incoming traffic rate of incoming UEs entering a cell; and
a PUCCH Resource Allocator configured to allocate PUCCH resources including a fixed number of PUCCH PRBs to a RRC connected UE in a radio access network.
2 : The system of claim 1 , wherein the PUCCH resources comprise a Scheduling Request (SR) and Channel State Information (CSI).
3 : The system of claim 2 , wherein, the PUCCH Resource Allocator is configured to assign the SR and the CSI to the incoming UEs and set the SR and the CSI periodicities for the incoming UEs.
4 . The system of claim 3 , wherein, the BS is configured to:
determine a connection type, and
when the connection type is a reestablishment of an RRC connection, reassign a same SR and CSI Resource and Configuration Index; or
when the connection type is a RRC Connection and Reconfiguration for a secondary carrier, reassign a same SR CSI Resource and Configuration Index and assign a new CSI.
5 . The system of claim 3 , wherein, the PUCCH Resource Allocator is configured to:
determine a connection type, and
when establishing an RRM connection, after a handover into the cell (Handin) request or a RRC Connection and Reconfiguration for a secondary cell/carrier addition for carrier aggregation (CA), execute a PUCCH Overload Check; and
when not overloaded, assign the PUCCH Resource; or
when overloaded, determine if an SR or CSI periodicity or both are at a maximum, and if not, increase the SR or CSI periodicity or both to a configured higher value, and apply the change in periodicity to the UE to be reconfigured, and assign the PUCCH Resource; or
if the SR or CSI periodicity or both are at a maximum, determine if the cause for the establishment of the maximum is an emergency or high priority cause, and if not reject an Admission Request due to PUCCH overload, and if so, preempt one or more already connected UE s to free up and reassign PUCCH resource to the incoming UE.
6 . The system of claim 1 wherein the Incoming-Traffic Tracker is configured to estimate a call origination, a handover into the cell (HandIn), a carrier aggregation, and a carrier addition for the incoming traffic rate.
7 . The system of claim 1 , wherein the BS is configured to use the incoming-traffic rate and a number of existing UEs already in the cell to determine if the PUCCH Resource Allocator needs to increase an SR or CSI capacity when it is in an overloaded condition or decrease the SR or CSI capacity or both when it is in an underloaded condition.
8 . The system of claim 7 , wherein the BS is configured to determine the overloaded or underloaded condition by:
obtaining, at the RRM, a retrieve rate of incoming RRC establishment requests (Ra), the Ra being a number of RRC connection requests per second;
determine a retrieve rate of RRC connection reconfiguration requests (Rca), the Rca being a retrieve rate of the RRC connection reconfiguration requests per second for the secondary cell/carrier addition for CA;
determine a retrieve rate of RRC Connection release requests (Rr), the Rr being a number of RRC connection release requests per second; and
determine a retrieve rate for Handns (Rh), the Rh being a number of RRC connection reconfiguration complete requests per second;
and determine and set an PUCCH overload or PUCCH underload status.
9 . The system of claim 7 , wherein the PUCCH Resource Allocator is configured to:
when an increase is needed, increase the SR or CSI periodicity or both; and
when a decrease is needed, decrease the SR or CSI periodicity or both.
10 . The system of claim 8 , wherein the BS is configured to:
release PUCCH resources allocated to an incoming UE;
perform a PUCCH underload check;
determine a PUCCH underload status; and
when the PUCCH is not underloaded, end the PUCCH underload check; or
when the PUCCH is underloaded, determine if the SR or CSI periodicity or both are at a minimum, and if so, end the PUCCH underload check, or if not, lower the SR or CSI periodicity or both.
11 . The system of claim 10 , wherein the BS is configured to determine the underload condition by an algorithm comprising:
CLs, CLc=current PUCCH resource or load of SR and CSI, respectively
LTs, LTc=a configured PUCCH Lower Threshold of SR and CSI, respectively
RLs
=
Ls
*
(
Ra
+
Rca
+
Rh
-
Rr
)
RLc
=
Lc
*
(
Ra
+
Rca
+
Rh
-
Rr
)
where
RLs, RLc=a Total additional PUCCH load in a next second of the SR and the CSI, respectively
Ls, Lc=the PUCCH resource needed for the incoming UE of SR and CSI, respectively; where
if (CLs+Ls+RLs<LTs), set PUCCH SR Overload Status to Underloaded, otherwise, set PUCCH SR Overload Status to not Underloaded; and
if (CLc+Lc+RLc<LTc), set PUCCH CSI Overload Status to Underloaded, otherwise, set PUCCH CSI Overload Status to not Underloaded.
12 : The system according to claim 9 , wherein the PUCCH Resource Allocator is configured to:
apply the increased or decreased SR or CSI periodicity, or both, to newly arriving UEs only.
13 . The system according to claim 7 , wherein the PUCCH Resource Allocator is configured use a same SR and CSI resource assignment and periodicity for the already connected UEs for until the already connected UEs depart from the cell.
14 . The system according to claim 7 , wherein, when the BS determines the SR or CSI periodicity, or both reach a maximum threshold and the BS determines that meeting of the maximum threshold is the overloaded condition, the BS is configured send an RRC connection reconfiguration to reallocate the existing UE's already in the cell with a smallest SR or CSI periodicity or both to a maximum SR or CSI periodicity or both.
15 . The system of claim 10 , wherein the BS is configured to determine the overload condition by an algorithm comprising:
CLs, CLc=a current PUCCH resource or load of the SR and the CSI, respectively
UTs, UTc=a configured PUCCH Upper Threshold of the SR and the CSI, respectively
RLs
=
Ls
*
(
Ra
+
Rca
+
Rh
-
Rr
)
RLc
=
Lc
*
(
Ra
+
Rca
+
Rh
-
Rr
)
where
RLs, RLc=a Total additional PUCCH load in a next second of the SR and the CSI, respectively
Ls, Lc=the PUCCH resource needed for the UE of SR and CSI, respectively; where
if (CLs+Ls+RLs>UTs), set a PUCCH SR Overload Status to overloaded, otherwise, set the PUCCH SR Overload Status to not overloaded; and
if (CLc+Lc+RLc>UTc) set PUCCH SR Overload Status to overloaded, otherwise, set PUCCH SR Overload Status to not overloaded.
16 . The system of claim 7 , wherein when the BS determines the PUCCH Status is overloaded and SR or CSI or both are at a maximum periodicity, the BS is configured to send an RRC reconfiguration to the UEs that have been assigned a smaller SR periodicity than a current UE to set the UEs the smaller SR or CSI periodicity or both to a current value.
17 . The system of claim 16 , wherein the BS is configured to incrementally assign a next current value to the next of the UEs having the smallest SR or CSI periodicity or both.
18 . The system of claim 1 , wherein the BS is configured not to send an RRC Reconfiguration to all UEs in the cell; and the BS is configured to send the RRC Reconfiguration to specific UEs to reallocate PUCCH resources.