LTE Small Cells and LTE-WLAN Aggregation

LTE and Wi-Fi (generally WLAN) can also work together in combined mode while enabling link aggregation of the two technologies to increase throughput. LTE continues be the anchor cell in licensed spectrum and therefore used as reliable technology for control and mobility management to secure QoS. WLAN is opportunistic unlicensed component used to increase the data rate.

LTE continues be the anchor cell in licensed spectrum and therefore used as reliable technology for control and mobility management to secure QoS. WLAN is opportunistic unlicensed component used to increase the data rate. 

There are two different available options for integrating LTE and WLAN according where the aggregation is actually executed, those are: LTE-WLAN Aggregation (LWA) and LTE WLAN Radio Level Integration with IPsec Tunnel (LWIP).

In LWA the aggregation of LTE and WLAN happens at RAN level. The packets are sent independently using the two technologies over split and switched bearers and are then reassembled by the Packet Data Convergence Protocol (PDCP) layer in the user equipment making the aggregation transparent to the upper layers. LWA is controlled by E-UTRAN NodeB (eNodeB), based on User Equipment (UE) measurement reporting, and supports two deployment scenarios:

• Collocated: when LTE Small Cell (or more generic eNodeB) and WLAN Access Points coexists
• Non-collocated: where the eNodeB and WLAN Access Point are connected via a new standardized interface, Xw, that supports control and data plane, this can be the case of Mobile Network Operator (MNO) partners with a WLAN operator

- LWIP