Macro-assisted multi-connectivity scheme in multi-RAT cellular systems
A novel Macro-assisted Multi-Connectivity (MC) mobility scheme for UEs traversing clusters of (mmWave) small cells (small-BS or SBS) under the coverage of the same 5G or LTE Macro-cell (macro-BS or MBS) is proposed. It keeps the same Control/User split scheme and C-Plane anchor at MBS, same as in LTE Dual Connectivity (DuCo or DC), yet extending DuCo with a multi-connectivity split bearer user plane. For example, MBS adopts a multi-way packet data convergence protocol (PDCP) bearer split based on routing weighted by channel quality, SBS's resource availability, etc. with or without inter-BS flow control. Utilizing the MC user plane, a macro-assisted make-before-break MC mobility can be enabled.
1. A method comprising:
establishing a radio resource control (RRC) connection with a macro base station (MBS) by a user equipment (UE) in a heterogeneous network having a macrocell served by the MBS and overlaying smallcells served by smallcell base stations (SBSs);
establishing a multi-connectivity (MC) multi-way split bearer U-plane for simultaneous data transmission with one or more base stations; and
performing macro-assisted make-before-break MC mobility by using the multi-way split bearer, wherein the make-before-break MC mobility involves switching between (N−1)-way and N-way of the multi-way split bearer, wherein N is an integer that is greater than one.
2. The method of claim 1 , wherein UE monitors and reports dynamic channel states to the MBS for a routing or a scheduling decision of loading traffic onto different sub-bearers of the multi-way split bearer.
3. The method of claim 1 , wherein the UE reorders Packet Data Convergence Protocol (PDCP) layer packets for a single downlink flow that arrives at the UE from one or more base stations.
4. The method of claim 1 , wherein the UE splits PDCP layer packets for a single uplink flow that is destined to the MBS through one or more base stations.
5. The method of claim 1 , wherein the UE adopts a dynamic weighted based U-plane routing and scheduling for the multi-way split bearer.
6. The method of claim 1 , wherein the multi-way split bearer switching is based on channel quality, resource availability, network policy, UE preference, and traffic loads.
7. The method of claim 1 , wherein the UE uses the multi-way split bearer to aggregate multi-cell bandwidth at PDCP layer for packets from one flow but through different base stations.
8. A User Equipment (UE) comprising:
a radio frequency (RF) transceiver that transmits and receives RF signals;
a control plane circuit that establishes a radio resource control (RRC) connection with a macro base station (MBS) using the RF transceiver in a heterogeneous network having a macrocell served by the MBS and overlaying smallcells served by smallcell base stations (SBSs);
a user plane circuit that establishes a multi-connectivity (MC) multi-way split bearer U-plane for simultaneous data transmission with one or more base stations; and
a mobility circuit that performs macro-assisted make-before-break MC mobility by using the multi-way split bearer, wherein the make-before-break MC mobility involves switching between (N−1)-way and N-way of the multi-way split bearer, wherein N is an integer that is greater than one.
9. The UE of claim 8 , wherein UE monitors and reports dynamic channel states to the MBS for a routing or a scheduling decision of loading traffic onto different sub-bearers of the multi-way split bearer.
10. The UE of claim 8 , wherein the UE reorders Packet Data Convergence Protocol (PDCP) layer packets for a single downlink flow that arrives at the UE from one or more base stations.
11. The UE of claim 8 , wherein the UE splits PDCP layer packets for a single uplink flow that is destined to the MBS through one or more base stations.
12. The UE of claim 8 , wherein the UE adopts a dynamic weighted based U-plane routing and scheduling for the multi-way split bearer.
13. The UE of claim 8 , wherein the multi-way split bearer switching is based on channel quality, resource availability, network policy, UE preference, and traffic loads.
14. The UE of claim 8 , wherein the UE uses the multi-way split bearer to aggregate multi-cell bandwidth at PDCP layer for packets from one flow but through different base stations.
15. A method comprising:
establishing a radio resource control (RRC) connection with a user equipment (UE) by a macro base station (MBS) in a multi-Radio Access Technology (RAT) network having a microwave macrocell served by the MBS and overlaying smallcells served by smallcell base stations (SBSs);
establishing a multi-connectivity (MC) multi-way split bearer U-plane together with the SBSs for providing simultaneous data transmission to the UE; and
performing macro-assisted make-before-break MC mobility for the UE by using the multi-way split bearer, wherein the MBS supports SBS addition or removal from the multi-way split bearer through a Radio Access Network (RAN) and a core network signaling to enable the multi-way bearer splitting or merging.
16. The method of claim 15 , wherein the MBS collects dynamic channel states for making a routing or a scheduling decision of loading traffic onto different sub-bearers of the multi-way split bearer.
17. The method of claim 15 , wherein the MBS exchanges signaling carrying weighting information with the SBSs and the UE for a weighted traffic splitting/merging at the packet data convergence protocol (PDCP) layer.
18. The method of claim 17 , wherein the PDCP layer packets routing/merging occurs for a single uplink flow that is destined to the MBS through one or more base stations.
19. The method of claim 17 , wherein the PDCP layer packets scheduling/splitting occurs for a single downlink flow that arrives at the UE through one or more base stations.
20. The method of claim 15 , wherein the make-before-break MC mobility involves switching between (N−1)-way and N-way of the multi-way split bearer, wherein N is an integer that is greater than one.
21. The method of claim 20 , wherein the multi-way split bearer switching is based on channel quality, resource availability, network policy, UE preference, and traffic loads.