scholarly journals Small Cells-The Future of Cellular Networks

2016 ◽  
Vol 78 (6-11) ◽  
Author(s):  
Ahmed M. Al-Samman ◽  
Tharek A. Rahman ◽  
Razali Ngah

The demands of high data rate transmission for future wireless communication technologies are increasing rapidly. The current bands for cellular network will not be able to satisfy these requirements. The millimeter wave (mm-wave) bands are the candidate bands for the future cellular networks. The 28 GHz band is the strongest candidate for 5G cellular networks. The large bandwidth at this band is one of the main parameters that make the mm-wave bands promising candidate for the future cellular networks. To know the wideband channel behavior in mm-wave bands, the wideband channel characterizations are required. In this paper, the 3D WINNER model is used to model the wideband channel at 28 GHz band. Based on this model, the time dispersion parameters at 28 GHz mm-wave band are investigated. The root mean square delay spread and the mean excess delay are the main parameters that can be used to characterize the wideband channel. Morever, the cumulative distribution function (CDF) is used to model the RMS delay spreads. The results show that the RMS delay spread varies between 4.1 ns and 443.7 ns.


2020 ◽  
Vol 75 (4) ◽  
pp. 369-382
Author(s):  
Moubachir Madani Fadoul

Abstract The rapid growth of small cells is driving cellular network toward randomness and heterogeneity. The multi-tier heterogeneous network (HetNet) addresses the massive connectivity demands of the emerging cellular networks. Cellular networks are usually modeled by placing each tier (e.g macro, pico and relay nodes) deterministically on a grid which ignores the spatial randomness of the nodes. Several works were idealized for not capturing the interference which is a major performance bottleneck. Overcoming such limitation by realistic models is much appreciated. Multi-tier relay cellular network is studied in this paper, In particular, we consider $${\mathscr {K}}$$ K -tier transmission modeled by factorial moment and stochastic geometry and compare it with a single-tier, traditional grid model and multi-antenna ultra-dense network (UDN) model to obtain tractable rate coverage and coverage probability. The locations of the relays, base stations, and users nodes are modeled as a Poisson Point Process. The results showed that the proposed model outperforms the traditional multi-antenna UDN model and its accuracy is confirmed to be similar to the traditional grid model. The obtained results from the proposed and comparable models demonstrate the effectiveness and analytical tractability to study the HetNet performance.


Author(s):  
Hyoungju Ji ◽  
Hyojin Lee ◽  
Seunghoon Choi ◽  
Youngbum Kim ◽  
Younsun Kim ◽  
...  

2020 ◽  
pp. 849-865
Author(s):  
Saif Hikmat Mousa ◽  
◽  
Mahamod Ismail ◽  
Rosdiadee Nordin ◽  
Nor Fadzilah Abdullah

To handle the huge traffic in cellular networks and increase the offered bandwidth for User Equipment (UE), we proposed two enhanced methods to simultaneously access the channels in Heterogeneous Bands (HetBands). The Enhanced Dual Band Femtocell (EDBF) is utilized in single Radio Access Technology (RAT) that comprises Long Term Evolution (LTE) only, while Enhanced Integrated Femto Wi-Fi (EIFW) cell can be used for multi-RAT network (LTE and Wi-Fi). Using the unlicensed band as a supplementary band that usually occupied by Wi-Fi devices (wDevices), a fair sharing can be achieved, and however it may result in reduced network throughput. This work proposes a novel framework to enhance the overall Base Station (BS) performance of both methods in unlicensed band, thus attaining optimal throughput and fair sharing. Firstly, we proposed a channel access scheme for each enhanced method adopts our new procedure that effectively use the scheme parameters (Tattempt, Ttrans, and Tsense) to enhance the BS performance. Secondly, two new approaches are proposed in our analytic model to obtain the channel and manage coexistence in unlicensed band based on the channel states and scheme's parameters. Thirdly, a new formulation is proposed in our dynamic algorithm to obtain the optimal fraction of channel time in unlicensed band (tf*), using the optimal power in licensed band (Pf*(s)). We validated our analysis in terms of fair sharing using simulation. Results show that our proposed framework substantially enhance the overall performance of both enhanced methods in terms of throughput, fraction of channel sharing time, and traffic balancing, which make EDBF and EIFW attractive small cells to be used (one type or both) in the deployments of current and future cellular networks.


2015 ◽  
Vol 64 (10) ◽  
pp. 4797-4806 ◽  
Author(s):  
Shaowei Wang ◽  
Wentao Zhao ◽  
Chonggang Wang

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