Research Article

User Association and Small-Cell Base Station On/Off Strategies for Energy Efficiency of Ultradense Networks

Algorithm 1

MAX-SINR algorithm.
(1)Users associate with BSs based on SINR
(2)Initialization:
(3); ;
(4)for 1 ≤ m ≤ M do
(5)if
(6)Associate user k with the BS m;
(7)Generate the candidate list for BS m;
(8)end if
(9)for
(10)Calculate the degrees of freedom of user k;
(11)Find user k which has minimal degrees of freedom, ;
(12)Calculate , ;
(13);
(14)Associates user with BS , ;
(15)Update ;
(16)if
(17)User k (1 ≤ k ≤ K) deletes the BS in its list ;
(18)end if
(19)end for
(20)end for
(21)until all users associate with BSs.
(22)SBSs on/off strategy:
(23)Initialization:
(24)All BSs hold “on”, i.e., ; ;
(25)Sort ;
(26)repeat
(27)Turn off FBSs i based on the load of FBSs;
(28)Update the EE by the user association algorithm, set , and record the number of FBSs turned off is n;
(29)until