Fractional frequency reuse schemes assigned to radio nodes in an LTE network
View Patent ↗Arrangements disclosed here provide an LTE E-RAN employing a hierarchical architecture with a central controller controlling multiple LTE radio nodes (RNs). The RNs may be clustered within the small cell network. A fractional frequency reuse (“FFR”) scheme is provided that dynamically computes the FFR allocations at individual RNs and configures the corresponding schedulers within each RN to improve cell-edge users' experience. Once an FFR pattern has been generated and frequencies allocated, UE throughput can be emulated to predict the resulting bit rates for each UE. Using the prediction, a scheduler emulation may be run to predict the behavior of the system. The results of each cell may then be collected to generate the performance of the entire system, which may in turn be used to generate a new or modified FFR pattern, or new or modified clustering. Optimization of the performance results in an optimized FFR pattern.
1. A method of optimizing transmission resource allocation in a radio access network (RAN) that includes a plurality of radio nodes (RNs) each associated with a cell and a services node operatively coupled to the plurality of RNs, the method comprising:
obtaining at least one system-wide performance metric representing operational performance of the RAN;
dividing the plurality of RNs into a plurality of clusters based on an interference metric that assigns to each of the plurality of clusters two or more of the plurality of RNs that interfere more strongly with one another than RNs assigned to different clusters; and
if the at least one system-wide performance metric is less than a target threshold, then adjusting a system-wide fractional frequency reuse (FFR) pattern used to allocate transmission resources to the plurality of RNs until the at least one system-wide performance metric meets or exceeds the target threshold, the system-wide FFR pattern including a plurality of cluster-based FFR patterns each being allocated to a different one of the plurality of clusters.
2. The method of claim 1 wherein adjusting the system-wide FFR pattern includes adjusting FFR scheme-related parameters used to generate the system-wide FFR pattern.
3. The method of claim 1 wherein adjusting the system-wide FFR pattern includes adjusting one or more of the plurality of cluster-based FFR patterns by adjusting at least one operator-specified value selected from a plurality of parameters which are used as input data.
4. The method of claim 3 wherein the plurality of parameters includes an FFR type specifying at least one criterion for allocating edge bands to the RNs in each cluster of the plurality of clusters.
5. The method of claim 4 wherein the plurality of parameters further includes a number of frequency resource blocks assigned to a center band allocated to the RNs in each cluster for use by UEs in a cell interior of each cell.
6. The method of claim 5 wherein the plurality of parameters further includes a scheduling granularity of the center band specifying a number of frequency resource blocks assigned to the center band which are scheduled together.
7. The method of claim 5 wherein the plurality of parameters further includes a scheduling granularity of the edge bands specifying a number of frequency resource blocks assigned to the edge bands which are scheduled together.
8. The method of claim 4 wherein the FFR type is selected from the group consisting of uniform FFR and load-based FFR, wherein uniform FFR allocates different edge bands of uniform size to each RN in a cluster and load-based FFR allocates to each RN in a cluster different edge bands having a size determined in part on load information obtained from the RNs in each cluster.
9. The method of claim 1 wherein adjusting the system-wide FFR pattern includes adjusting RN clustering parameters.
10. The method of claim 9 wherein the RN clustering parameters include a total number of clusters into which the plurality of RNs in the RAN are to be divided.
11. The method of claim 1 wherein the transmission resources are resources used for downlink transmission.
12. The method of claim 1 wherein the transmission resources are resources used for uplink transmission.
13. The method of claim 1 wherein the transmission resources are resources used for uplink and downlink transmission.
14. The method of claim 13 wherein, for at least one of the plurality of clusters, a cluster-based FFR pattern generated for uplink transmission is the same as a cluster-based FFR pattern generated for downlink transmission.
15. A method of optimizing transmission resource allocation in a radio access network (RAN) that includes a plurality of radio nodes (RNs) each associated with a cell and a services node operatively coupled to the plurality of RNs, the method comprising:
obtaining at least one system-wide performance metric representing operational performance of the RAN; and
if the at least one system-wide performance metric is less than a target threshold, then adjusting a system-wide fractional frequency reuse (FFR) pattern used to allocate transmission resources to the plurality of RNs until the system-wide performance metric meets or exceeds the target threshold, the system-wide FFR pattern including a plurality of cluster-based FFR patterns each being allocated to a different cluster of RNs, the plurality of RNs in the RAN being divided into a plurality of clusters;
wherein adjusting the system-wide FFR pattern includes adjusting one or more of the plurality of cluster-based FFR patterns by adjusting at least one operator-specified value selected from a plurality of parameters which are used as input data, wherein the plurality of parameters includes an FFR type specifying at least one criterion for allocating edge bands to the RNs in each cluster, wherein the FFR type is selected from the group consisting of uniform FFR and load-based FFR, wherein uniform FFR allocates different edge bands of uniform size to each RN in a cluster and load-based FFR allocates to each RN in a cluster different edge bands having a size determined in part on load information obtained from the RNs in each cluster;
wherein the load information is selected from the group consisting of a load of each RN in a cluster, a number of active user equipment (UEs) served by each RN in a cluster, and UE-specific information, wherein the UE-specific information is selected from the group consisting of reference signal received power (RSRP), load, quality of service (QoS), sub-band channel quality indicators (CQis), buffer status or latencies, and current or past key performance indicators (KPis) maintained per RN or per UE.
16. A method of optimizing transmission resource allocation in a radio access network (RAN) that includes a plurality of radio nodes (RNs) each associated with a cell and a services node operatively coupled to the plurality of RNs, the method comprising:
obtaining at least one system-wide performance metric representing operational performance of the RAN; and
if the at least one system-wide performance metric is less than a target threshold, then adjusting a system-wide fractional frequency reuse (FFR) pattern used to allocate transmission resources to the plurality of RNs until the at least one system-wide performance metric meets or exceeds the target threshold, the system-wide FFR pattern including a plurality of cluster-based FFR patterns each being allocated to a different cluster of RNs, the plurality of RNs in the RAN being divided into a plurality of clusters, wherein the at least one system-wide performance metric is selected from the group consisting of: cell packet throughput, 5% cell edge user throughput, and user throughput cumulative distribution function (CDF), call drop ratio, call setup success rate, radio link failure rate, and handover delay.
17. A non-transitory computer readable medium, comprising instructions for causing a computing environment to perform the method of claim 1 .
18. A services node controlling a plurality of radio nodes (RNs) in a radio access network (RAN), the plurality of RNs communicating with a plurality of user equipment (UE) in the RAN, comprising:
a processor; and
a performance evaluation module operatively associated with the processor, the performance evaluation module having an input for obtaining at least one system-wide performance metric representing operational performance of the RAN, the performance evaluation module being configured such that if the at least one system-wide performance metric is less than a target threshold, then adjusting a system-wide fractional frequency reuse (FFR) pattern used to allocate transmission resources to the plurality of RNs until the at least one system-wide performance metric meets or exceeds the target threshold, the system-wide FFR pattern including a plurality of cluster-based FFR patterns each being allocated to a different cluster of RNs, the plurality of RNs in the RAN being divided into a plurality of clusters based on an interference metric that assigns to each of the plurality of clusters two or more of the RNs that interfere more strongly with one another than RNs assigned to different clusters.