Rising popularity of 5G communications is making tremendous demands on the cellular network operators for providing true 5G services to the users. With limited numbers of 5G users initially, the investments for 5G services can be very high. In the early stage of 5G deployments, the 5G cells would not be lavishly spread and there would be 5G coverage holes. The operators can provide seamless services to the 5G users by inter working with the existing 4G Long-Term Evolution (LTE) network. The 5G inter working with fully deployed LTE would not only provide fast and seamless coverage but would also provide economic viability to the network operators. In this paper we survey and consolidate the 4G-5G inter working solutions that can assist in attaining the insight about various inter working possibilities and their challenges. It is important that a network operator is able to optimize its deployed infrastructure while being able to guarantee fast and seamless transition to 5G for its subscribers. To this regard, we evaluate the performance and radio resource management challenges for different 4G-5G dual connectivity options proposed by 3rd Generation Partnership Project (3GPP) standardization. We also discuss spectrum sharing possibilities between 4G and 5G wireless networks. Finally, various research challenges and discussions on path for migration to 5G standalone networks are also presented.

Connected living − the true vision of the Internet of Things (IoT) – offers improvement in the quality of life while presenting new business avenues. A combined effort by researchers, industries, manufacturers, service providers, and other stakeholders is required to address distinct IoT requirements. This convergence is expected to unleash a new dimension of opportunities that cannot be fully realized with conventional solutions. At the same time, 5G wireless promises a new connected ecosystem with potential technologies, like massive Multiple-Input and Multiple-Output (MIMO), Cloud Radio Access Network (C-RAN), Heterogeneous-CRAN (H-CRAN), mmWave, software-defined networking, information (content or data)-centric communication, Multi-RAT, and novel multiplexing. Since emerging 5G network is expected to revolutionize the way of communication, its design and standardization should consider IoT as one of the major guidelines. To this regard, we present technical details of emerging 5G networks inline with pressing IoT requirements, essential for the ultimate shaping of a connected living. We also delineate limitations of legacy networks to provide for peculiarities of IoT requirements.

Emerging mmWave enabled 5G wireless communications, offer tremendous increase in data demands and better quality expectations. However, high mmWave frequencies call for directional beamforming to overcome propagation limitations and enhance spatial capabilities. The establishment of new directional paradigm challenges the current Discontinuous Reception (DRX) mechanism for power saving in the User Equipment (UE). In this article, we introduce new Directional-Discontinuous Reception (DDRX) for directional air interface expected in mmWave enabled 5G communications. DDRX mechanism emphasizes the importance of beam searching for alignment of directional beams between UE and 5G base station (gNB), after every sleep cycle. Beam searching, though inevitable, reduces the effective sleep time. We propose three new DDRX mechanisms: Integrated DDRX (I-DDRX), Standalone DDRX (S-DDRX), and Cooperative DDRX (C-DDRX) to limit the impediments on power saving. Probabilistic estimation of UE's power saving and delay is performed for all the three different DDRX mechanisms using semi-Markov process. The power saving achieved in IDDRX is 12.1 percent higher than S-DDRX. The power saving of C-DDRX is 6.1 percent higher than S-DDRX. Analytical results of DDRX proposals are validated by simulation studies, performed over real wireless trace.

Internet of Things (IoT) imbued with several heterogeneous services and applications is integral to the ultimate realization of connected living. However, massive connectivity would pose huge challenges not only due to immense scalability but also due to diverse characteristics of periodicity, delay-criticality, and quality-of-service (QoS) requirement. One important trend of this diversity is that the connected devices would manifest different priorities. Random access procedure (RAP) is the first step by which most devices establish connection to the base station. A major transformation is urgently needed in RAP for cellular IoT as the volume of connected devices would far exceeds human oriented connections of the legacy networks. To prioritize the RAP for IoT devices, we propose novel online control algorithm that enables the most likely successful preamble transmission for the devices that manifest higher priority requirements. In the proposed algorithm, the number of active devices in each priority is recursively estimated based on Bayesian rule and then the preambles to each priority are accordingly allocated. We extend our proposal by adopting access class baring (ACB) to optimize the algorithm and subsequently, enhance it further by incorporating access delay requirements. Extensive simulations show the effectiveness of proposed algorithms over multiple priorities and confirm that the proposed algorithms are able to resolve congestions for massive activation of IoT devices.

The next generation mobile networks would transform not only the way people communicate, but also how they access physical entities. The convergence of things into human-centric wireless communication would unleash opportunities for a better quality of life, while offering new business avenues. Conventional solutions cannot fully realize dense, diverse and heterogeneous dimensions expected in unified connectivity of “things” over the “Internet” (IoT). At the same time, emerging 5G wireless networks promise improvement in spectrum availability, ubiquitous connectivity, overall throughput and energy efficiency. However, to encompass the dynamics of human-centric and machine-centric communication, it is important to explore 5G wireless technologies for flexibility and scalability. To this regard, we propose flexible beamforming (FBF) antenna architecture that allows flexibility in terms of data rates, coverage and scalability in an energy-efficient manner. We capture initial lessons from investigations on mmWaves, beamforming, downtilt and small cell deployment strategies. Our simulation experiments, using real 5G testbed parameters, validate performance benefits of the proposed FBF antenna architecture. With around 4 Gbps throughput capacity, FBF promises higher scalability. Moreover, FBF achieves 53% higher energy efficiency than maximum power beams.