Methods and apparatus for multiple connectivity in heterogeneous network
Methods are provided to perform multiple-connectivity operation in the heterogeneous network. In one novel aspect, multiple-connectivity is configured with one microwave macro cell and multiple small cells. UE establishes control plane connectivity with the microwave macro cell, where the S1-MME interface is terminated. Multiple small-cell base stations provide traffic data together to the UE and are connected with Xn interfaces. One small-cell base station in the set of the configured small base stations is an UP anchor small-cell base station, where S1-U interface is terminated. Other small base stations are UP assistance small base station. In one embodiment, the set of small base stations and the UP anchor small base stations can be changed based on the measurement report/results of the different cells as well as the cell loading status. The anchor base station can be changed either by the UE or through network configuration.
1. A method comprising:
configuring control plane (CP) connectivity by a user equipment (UE) in a heterogeneous wireless network;
configuring a set of small-cell base stations to form a user plane (UP) connectivity, wherein the UP connectivity is different from the CP connectivity;
selecting one of the small-cell base stations as an UP anchor station and one or more small-cell base stations as UP assistance stations, wherein the UE communicates with the UP anchor station and at least one UP assistance station for data traffic packets, and wherein the UP anchor station forwards data traffic packets to the UP assistance stations;
performing signaling transmission through the configured CP and traffic data transmission/reception through the UP anchor station and the UP assistance stations;
establishing a radio link control (RRC) connection through the CP with a macro-cell base station; and
performing measurements on the set of UP small-cell base stations.
2. The method of claim 1 , wherein the CP connectivity is connected to the macro-cell base station, wherein an S1-U interface from the wireless network is terminated at the UP anchor station, and wherein CP procedures of the UE are performed on the macro-cell through the macro-cell base station.
3. The method of claim 1 , wherein the set of small-cell base stations are millimeter wave (mmW) base stations.
4. The method of claim 1 , wherein the UP connectivity is formed by integrating the set of small-cell base stations at different protocol layers.
5. The method of claim 4 , wherein the UP connectivity is formed by integrating the set of small-cell base stations at a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, or a MAC layer.
6. The method of claim 1 , further comprising:
sending measurement reports of the small-cell base stations through the CP to the wireless network upon detecting one or more triggering events;
receiving one or more UP configuration messages from the wireless network; and
applying the received UP configuration to the set of small-cell base stations.
7. The method of claim 6 , wherein the UP configuration message from the wireless network indicates a change of the UP anchor station.
8. The method of claim 6 , where the triggering event is detecting one or more small-cell base stations with better signal quality than the UP anchor station.
9. The method of claim 1 , further comprising:
detecting one or more small-cell base stations with better signal quality than the UP anchor station;
selecting a new anchor UP station based on the measurements; and
informing the wireless network regarding the new anchor UP station.
10. A user equipment (UE), comprising:
one or more first radio frequency (RF) transceivers that transmit and receive radio signals of small-cell signals in a heterogeneous wireless network;
a second RF transceiver that transmits and receives radio signals of macro-cell signals in the heterogeneous wireless network;
a memory; and
a processor coupled to the memory, the processor configured to configure a CP connectivity;
configure a set of small-cell base stations to form a UP connectivity, wherein the UE communicates with the UP anchor station and at least one UP assistance station for data traffic packets, and wherein the UP connectivity is different from the CP connectivity;
select one of the small-cell base stations as an UP anchor station and one or more small-cell base stations as UP assistance stations, and wherein the UP anchor station forwards data traffic packets to the UP assistance stations;
perform signaling transmission through the configured CP and traffic data transmission/reception through the UP anchor station and the UP assistance stations;
establish a radio link control (RRC) connection through the CP with a macro-cell base station; and
perform measurements on the set of UP small-cell base stations.
11. The UE of claim 10 , wherein an S1-U interface from the wireless network is terminated at the UP anchor station, the CP connectivity is connected to the macro-cell base station, and wherein CP procedures of the UE are performed on the macro-cell through the macro-cell base station.
12. The UE of claim 10 , wherein the set of small-cell base stations are millimeter wave (mmW) base stations.
13. The UE of claim 10 , wherein the UP connectivity is formed by integrating the set of small-cell base stations at different protocol layers.
14. The UE of claim 13 , wherein the UP connectivity is formed by integrating the set of small-cell base stations at a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, or a MAC layer.
15. The UE of claim 10 , wherein the processor is further configured to
detect one or more small-cell base stations with better signal quality than the UP anchor station;
select a new anchor UP station based on the measurements; and
inform the wireless network regarding the new anchor UP station.
16. The UE of claim 10 , wherein the processor is further configured to send measurement reports of the small-cell base stations through the CP to the wireless network upon detecting one or more triggering events; and receive one or more UP configuration messages from the wireless network, wherein the UP configurator applies the received UP configuration to the set of small-cell base stations.
17. The UE of claim 16 , wherein the UP configuration message from the wireless network indicates a change of the UP anchor station.
18. The UE of claim 16 , where the triggering event is detecting one or more small-cell base stations with better signal quality than the UP anchor station.