Apparatus and method for adaptive transmission during almost blank subframes in a wireless communication network
View Patent ↗A system and method for communication in a wireless communication network are disclosed. One embodiment of the system includes an overlay access node that supports Almost Blank Subframes (ABSs). The overlay access node, such as macro eNB, can receive measurement results from one or more user equipments, including macro user equipments (UEs) and/or pico (UEs), either directly or via an underlay access node, such as a pico eNB. The macro eNB can determine a set of macro UEs that are sufficiently close to the macro eNB for transmission during ABSs with a low transmission power or beamforming without significant interference to the pico UEs. This scheme improves the throughput of transmission between the macro eNB and macro UEs while reducing interference to the pico UEs.
1. A method of operating an overlay access node in a wireless communication network including one or more underlay access nodes, the method comprising:
receiving, by the overlay access node, an indication of at least one power measurement associated with one or more overlay access nodes and the underlay access nodes, wherein the overlay access node is configured to transmit data during one or more almost blank subframes (ABSs);
selecting, by the overlay access node, at least one user equipment (UE) to communicate with the overlay access node during one or more ABSs, based at least partly on the indication, wherein the at least one UE is in communication with the overlay access node, but not with the underlay access nodes, during the one or more ABSs;
determining, by the overlay access node, a first power level for communicating with the at least one UE during the one or more ABSs, wherein the first power level is lower than a second power level used during non-ABS subframes; and
transmitting, by the overlay access node, the data to the at least one UE during the one or more ABSs.
2. The method of claim 1 , wherein at least one other UE is in communication with at least one of the underlay access nodes during the one or more ABSs, and wherein the indication of the at least one power measurement is associated with power measurement by the at least one other UE.
3. The method of claim 2 , wherein receiving the indication comprises receiving a measurement from at least one of the underlay access nodes via a backhaul link.
4. The method of claim 2 , wherein receiving the indication comprises receiving a measurement wirelessly from the at least one other UE.
5. The method of claim 1 , wherein receiving the indication comprises receiving a measurement wirelessly from the at least one UE.
6. The method of claim 5 , wherein the indication is based at least partly on power measurement by the at least one UE of one or more signals from one or more of the overlay access nodes and the one or more underlay access nodes.
7. The method of claim 6 , wherein the indication is based at least partly on a ratio of (1) Reference Signal Received Power (RSRP) measurement of a signal from the overlay access node to (2) RSRP measurement of a signal from one of the underlay access nodes.
8. The method of claim 6 , wherein the indication comprises an indicator indicative of proximity of the at least one UE to one or more of the overlay access nodes and the underlay access nodes.
9. The method of claim 1 , further comprising communicating, by the overlay access node, data and/or control information with the at least one UE at the first power level.
10. The method of claim 1 , wherein determining the first power level comprises using the indication.
11. The method of claim 1 , further comprising transmitting, by the overlay access node, signaling to the at least one UE, wherein the signaling is indicative of at least one power ratio of a data signal to a reference signal during the one or more ABS, during one or more non-almost blank subframes (non-ABSs), or during both.
12. The method of claim 11 , wherein the power ratio comprises a power ratio of Physical Downlink Shared Channel (PDSCH) Energy per Resource Element (EPRE) to Cell-specific Reference Symbol (CRS) EPRE.
13. The method of claim 11 , wherein the ratio is determined based on the first power level.
14. The method of claim 11 , further comprising extending a range of values of one or more of parameters ρA and ρB by extending/shifting a UE-specific parameter PA in a PDSCH-Config message defined in 3GPP LTE TS 36.331 release 10 or later.
15. The method of claim 11 , wherein transmitting the signaling comprises using radio resource control (RRC) signaling.
16. The method of claim 1 , further comprising:
determining, by the overlay access node, a relative position of the at least one UE; and communicating, by the overlay access node, data and/or control information to the at least one UE during the one or more ABSs, using a directional transmission.
17. The method of claim 1 , further comprising transmitting, by the overlay access node, signaling to the at least one UE, wherein the signaling includes at least one parameter indicative of transmission power used for communication during the one or more ABSs.
18. The method of claim 17 , further comprising receiving a Channel Quality Index (CQI) measurement modified based at least partly on the at least one parameter.
19. The method of claim 1 , wherein the overlay access node comprises a macro evolved Universal Terrestrial Radio Access Network (UTRAN) node B (eNB), and wherein the underlay access nodes comprise a pico eNB.
20. The method of claim 1 , wherein the overlay access node is at least part of an aggressor cell, and wherein at least one of the underlay access nodes is at least part of a victim cell.
21. An overlay access node comprising:
a memory storing computer readable instructions executable by one or more processors, the one or more processors configured to:
receive an indication of at least one power measurement associated with the overlay access node and/or one or more underlay access nodes;
select at least one user equipment (UE) to communicate with the overlay access node during one or more almost blank subframes (ABSs), based at least partly on the indication;
determine a first power level for the overlay access node to communicate with the at least one UE during the one or more ABSs, wherein the first power level is lower than a second power level used during non-ABS subframes; and
transmit data from the overlay access node to the at least one UE during the one or more ABSs, wherein the at least one UE is not in communication with the underlay access nodes during the one or more ABSs.