  In ultra-dense millimeter wave (mmWave) networks, mmWave signals suffer from
severe path losses and are easily blocked by obstacles. Meanwhile, ultra-dense
deployment causes excessive handovers, which reduces the data link reliability.
To alleviate the above issues, the novel technology, known as
multi-connectivity enabled user association (MCUA) is incorporated in this
letter. We aim to jointly optimize MCUAs and downlink (DL) power allocations
(PAs) to maximize the DL rate of each user simultaneously, rather than total.
This is a non-convex nonlinear 0-1 mixed integer multi-objective optimization
problem and quite complicated. To solve it, we first use the weighted sum
method to scalarize it as a single-objective optimization problem (SOOP), and
then relax the binary association variables to real ones. Considering that the
relaxed SOOP is still non-convex, we perform a series of transformations upon
it and make it a differential of convex programming. Finally, we develop an
iterative algorithm based on the convex-concave procedure to solve the SOOP.
Numerical results are presented to demonstrate the effectiveness of the
proposed algorithms.

Networking and Internet Architecture