Methods and apparatus for dual connectivity operation in a wireless communication network
Dual-connectivity for the User Equipment (UE) in a cellular network is performed by monitoring a plurality of cells. During dual-connectivity, the UE may be simultaneously connected to one serving cell for the Control Plane (C-plane) and to another serving cell, controlled by a different eNodeB, for the User Plane (U-plane). In another embodiment, the dual-connected UE monitors a Physical Downlink Control Channel (PDCCH) from the first eNB and monitors an EPDCCH from the second eNB.
1. A method, comprising:
configuring a user equipment (UE) in a cellular network for reception of waveforms from, or transmission of waveforms to, more than one base station (eNB) in the cellular network transmitting in overlapping or non-overlapping wireless spectrum; and
designating one of the more than one base station for transmission/reception of common and dedicated radio resource control (RRC) and non-access stratum (NAS) signaling, wherein a full physical random access channel (PRACH) configuration includes a set of contention based PRACH signatures configured for each base station (eNB) of the cellular network to enable a complete random access procedure including preamble transmission, random access response, initial uplink transmission corresponding to a random access response grant and contention resolution for a cell.
2. The method of claim 1 , further comprising designating said one of the more than one base station as a mobility anchor to a core network.
3. The method of claim 2 , wherein the UE initializes a random sequence generator as a function of a Cell Radio Network Temporary Identifier (C-RNTI) associated with the base station from which it received a scheduling grant for respective transmission.
4. The method of claim 1 , wherein the UE is configured with two or more separate Cell Radio Network Temporary Identifiers (C-RNTI) for transmitting or receiving from each of the more than one base station.
5. The method of claim 1 , wherein a first base station designated for transmission/reception of common and dedicated radio resource control (RRC) and non-access stratum (NAS) signaling configures at least one secondary base station of the cellular network, to which the first base station is connected via a backhaul communications link, for transmission/reception to/from the UE configured for reception or transmission of waveforms from or to a plurality of base stations (eNB) of the cellular network.
6. The method of claim 5 , wherein the UE initializes a random sequence generator as a function of a Cell Radio Network Temporary Identifier (C-RNTI) associated with the base station from which it received a scheduling grant for respective transmission.
7. The method of claim 1 , wherein the UE transmits data to the base station from which it received a scheduling grant for respective transmission.
8. The method of claim 1 , wherein the UE is configured to transmit uplink control signaling on separate physical uplink control channels to a plurality of base stations (eNB) of the cellular network.
9. The method of claim 8 , wherein the UE transmits Hybrid Automatic Repeat reQuest acknowledgement (HARQ-ACK) feedback to the base station (eNB) of the cellular network from which a corresponding downlink data transmission was received or control information indicating release of a semi-persistent scheduling process.
10. The method of claim 8 , wherein the UE transmits channel state information (CSI) feedback for a cell on a physical uplink control channel (PUCCH) of one of serving cells controlled by the base station requesting CSI.
11. The method of claim 8 , wherein resources for a physical uplink control channel for a scheduling request (SR) are independently configured for the plurality of base stations (eNB) of the cellular network.
12. The method of claim 8 , wherein the UE:
when a buffer status report (BSR) needs to be transmitted for a respective base station (eNB) of the cellular network;
and if there is no Uplink Shared Channel (UL-SCH) resource available for that respective base station (eNB) of the cellular network over a defined maximum time period;
and if the UE is not configured with a valid PUCCH resource in any transmission time interval (TTI);
initiates a random access response to that respective base station (eNB) of the cellular network;
or otherwise transmits a scheduling request (SR) on PUCCH of the respective base station (eNB) of the cellular network according to an SR transmission procedure.
13. The method of claim 12 , wherein the UE initiates a random access process or otherwise transmits a scheduling request (SR) on PUCCH to a designated base station (eNB) of the cellular network.
14. The method of claim 8 , wherein a single resource for a physical uplink control channel for a scheduling request (SR) is configured for the plurality of base stations (eNB).
15. The method of claim 1 , wherein the random access response is scheduled on a common search space of a cell.