The Impact of Efficient Transport Blocks Management on the Downlink Power in MIMO Spatial Multiplexing of LTE-A

Radio spectrum for mobile operators is an expensive resource that should be wisely provisioned to meet users' demands. In long term evolution-advanced, the number of physical resource blocks (PRBs) are used to gauge the users' needs. Accordingly, there is a time in the network when it is beneficial to gain the advantages of consuming the unused PRBs in the transport block (TB) context to operate at a significantly lower power cost per PRB. The novelty of the letter is that the 3rd generation partnership project (3GPP) standard tables are used with multiple-input-multiple-output (MIMO) spatial multiplexing mode, to control the transport block size (TBS) index. This can be done by setting more PRBs and hence changing the modulation order that leads to reducing the transmitted power. In addition to that, MIMO layers, the prerequisite throughput, the intercell interference as well as the channel conditions of each user are considered as constraints to improve the downlink power efficiency. To describe the above-stated problem, an optimization problem is formulated as binary integer nonlinear program, which is very difficult to solve. Thus, a reformulation linearization technique based on a branch-and-bound framework is used to simplify the aforementioned BINLP.