The Full Dimension-MIMO (FD-MIMO) technology is capable of achieving huge improvements in network throughput with simultaneous connectivity of a large number of mobile wireless devices, unmanned aerial vehicles, and the Internet of Things (IoT). In FD-MIMO, with a large number of antennae at the base station and the ability to perform beamforming, the capacity of the physical downlink shared channel (PDSCH) has increased a lot. However, the current specifications of the 3rd Generation Partnership Project (3GPP) does not allow the base station to perform beamforming techniques for the physical downlink control channel (PDCCH), and hence, PDCCH has neither the capacity nor the coverage of PDSCH. Therefore, PDCCH capacity will still limit the performance of a network as it dictates the number of users that can be scheduled at a given time instant. In Release 11, 3GPP introduced enhanced PDCCH (EPDCCH) to increase the PDCCH capacity at the cost of sacrificing the PDSCH resources. The problem of enhancing the PDCCH capacity within the available control channel resources has not been addressed yet in the literature. Hence, in this paper, we propose a novel beamformed PDCCH (BF-PDCCH) design which is aligned to the 3GPP specifications and requires simple software changes at the base station. We rely on the sounding reference signals transmitted in the uplink to decide the best beam for a user and ingeniously schedule the users in PDCCH. We perform system level simulations to evaluate the performance of the proposed design and show that the proposed BF-PDCCH achieves larger network throughput when compared with the current state of art algorithms, PDCCH and EPDCCH schemes.
@cite_14: 
@cite_13: This paper presents optimal and efficient suboptimal resource allocation algorithms for the downlink control channel of the Third Generation Partnership Project-Long Term Evolution (3GPP-LTE) standard. A novel formulation of this resource allocation problem as a pure binary-integer program called the set packing problem is performed. This problem has been well-studied in operations research. In addition a greedy heuristic sub-optimal algorithm that reduces the processing complexity involved in finding the optimal solution and also approaches the optimal performance is presented. Performance comparisons of these proposed schemes based on Monte-Carlo simulations in a 5 MHz bandwidth LTE system are provided. The results prove that the proposed algorithms can significantly improve the system's cell-edge performance.
@cite_3: In Long Term Evolution (LTE), the provision of Quality of Service (QoS) strongly depends on the efficiency with which control resources are allocated. Unfortunately, the design of the control channel, the Physical Downlink Control Channel (PDCCH), is not flexible enough to support Intercell Interference Coordination (ICIC) and hence, its degradation at cell edges (a well known issue in LTE) severely jeopardizes system performance. This problem acquires especial relevance in realistic large scale deployments where Signal to Interference plus Noise Ratio (SINR) distributions are much worse than the ones predicted by means of hexagonal layouts. Thus, this paper investigates the challenge of improving SINR levels at cell edges in order to enhance the performance of the PDCCH. The proposed scheme adjusts the power allocated to the PDCCH at each cell in order to improve SINR distributions (minimizing the usage of control resources) and, due to its multiobjective nature, it considers several perspectives of the problem. The results show that gains in the order of 25 can be obtained in severely interfered cells while overall energy savings are around 50 .
@cite_13 , authors have presented an algorithm to optimally schedule the users in PDCCH and thus, increase the control channel capacity. In @cite_14 , authors have proposed a novel method of allocation for cell radio network temporary identifiers and increase the control channel capacity. In @cite_3 , authors propose power allocation techniques to improve the control channel capacity. However, none of the above papers discussed the beamforming and exploited the large antennae structure for increasing the control channel capacity. Further, we have implemented the optimal LTE-PDCCH scheduling algorithm presented in @cite_13 , and compared its performance against the proposed BF-PDCCH design in .