  Maintaining multiple wireless connections is a promising solution to boost
capacity in fifth-generation (5G) networks, where user equipment is able to
consume radio resources of several serving cells simultaneously and potentially
aggregate bandwidth across all of them. The emerging dual connectivity paradigm
can be regarded as an attractive access mechanism in dense heterogeneous 5G
networks, where bandwidth sharing and cooperative techniques are evolving to
meet the increased capacity requirements. Dual connectivity in the uplink
remained highly controversial, since the user device has a limited power budget
to share between two different access points, especially when located close to
the cell edge. On the other hand, in an attempt to enhance the uplink
communications performance, the concept of uplink and downlink decoupling has
recently been introduced. Leveraging these latest developments, our work
significantly advances prior art by proposing and investigating the concept of
flexible cell association in dual connectivity scenarios, where users are able
to aggregate resources from more than one serving cell. In this setup, the
preferred association policies for the uplink may differ from those for the
downlink, thereby allowing for a truly decoupled access. With the use of
stochastic geometry, the dual connectivity association regions for decoupled
access are derived and the resultant performance is evaluated in terms of
capacity gains over the conventional downlink received power access policies.
