China
Africa
Explore chapters and articles related to this topic
The Future of the Enterprise Lan
Published in Marcus K. Weldon, The Future X Network, 2018
Therefore, for applications that require a consistent quality of experience or session continuity while mobile, a cellular service is used. The macro cellular network or a distributed antenna system (DAS) — acting as a local repeater for an externally originated macro cellular signal — most often provides enterprise cellular coverage today. However, to meet the capacity and coverage requirements of the entire set of enterprise applications — as well as rising device density — what is needed are enterprise small cells, using licensed cellular spectrum. These small cells are typically deployed by mobile network operators and play a hybrid private/public access role in the enterprise, allowing private access to enterprise users within the enterprise location, but seamless hand-off to the public macro-cellular network, outside the enterprise. Initially, starting around 2010, small cells were deployed to provide indoor coverage for mobile communications due to the inferior penetration of the macro radio signal inside buildings. But with the increasing prevalence of mobile broadband data services, the data capacity they provide has become an important complement.
Microwave Photonics
Published in Chi H. Lee, Microwave Photonics, 2017
Today, the so-called AOCs play a significant role, for example, in storage and data centers or other short-range interconnections. High-performance and ultrahigh-speed computing connectivity can be achieved. These AOCs are optical links of Figure 1.20a completed by corresponding electrical connectors and power supplies. Many products are available on the market. Particular products are using broadband analog transmission suitable for radio-over-fiber (RoF) techniques, more discussed in detail in the following section. L-, S-, and C-band and even Ku- and Ka-band links can carry microwave signals over long distances due to fiber’s low insertion loss. The link distances can range from a few hundred meters to >10 km. AOCs can replace coaxial cables with the additional advantage of lightweight and immunity to electromagnetic interference from external RF sources. RoF solutions up to ca. 100 GHz are available for the data and video transport from remote satellite antennas, communication links on ships, trains, and airplanes, distribution of clock signals and signals in phased array systems, including delay lines, and secure interconnections between buildings. In this field, another term has been defined: distributed antenna system (DAS). An HFC DAS solution can connect existing Cat-5/6 cabling structures with new services like 4G LTE and provides a scalable technique for enterprises to invest as it grows.
5G Disruptive Technologies and Architecture
Published in Ashish Bagwari, Geetam Singh Tomar, Jyotshana Bagwari, Advanced Wireless Sensing Techniques for 5G Networks, 2018
Anu Mangal, M.A. Rizvi, Shadab Pasha Khan
In a distributed antenna system, there are both active and passive elements. For example, when a signal comes from an outside tower and reaches a building, it gets attenuated and suffers from penetration loss. In DAS, a base station is installed in the building and the DAS element (master unit) is equipped with that capability. Then in the complete building, remote units are located at different places which coordinate with the master unit. This remote unit provides its signals to the other elements. So, the DAS consist of many antennas which are all distributed throughout a building. Hence, the user is much closer to the area from where the signal is coming. This provides a much better user experience.
Energy-efficient power allocation scheme for distributed MISO system with transmit correlation
Published in International Journal of Electronics, 2018
Benben Wen, Xiangbin Yu, Ying Wang, Xiaoyu Dang
Traditional communication technologies mainly focus on improving the system spectral efficiency (SE) while neglecting the energy saving. The increase of SE is excessively at the expense of the huge energy consumption. To reduce the energy consumption of the communication system effectively, the green communication is proposed recently; it aims at pursuing high energy efficiency (EE) and has received considerable attention (Feng et al., 2013; Li, Xu, Xiong, &Yang, 2011). Moreover, the fifth-generation mobile communication system also regards the increase of EE as one of the main goals (Cavalcante, Stanczak, Schubert, & Eisenblaetter, 2014; Wang et al., 2014). Distributed antenna system (DAS) can enhance the system capacity and lower the transmit power, and has been an ideal technique to improve EE (Heath, Peters, Wang, & Zhang, 2013; Heath et al., 2013; Kim, Lee, Lee, & Lee, 2012). Different from the conventional centralized antenna system (CAS), the remote antenna units (RAUs) in DAS are separately placed in the cell, and linked to the central processing unit (CPU) via optical fibers, coaxial cables and dedicated wired links (Park, Lee, & Lee, 2012). As the RAUs are scattered in the cell, DAS can reduce the average access distance of the mobile station, and thus the transmitted power is lowered. Therefore, the DAS can obtain higher EE than the CAS.
Architect’s role to improve in-building wireless coverage
Published in Cogent Engineering, 2020
Mohammad Tanvir Kawser, Zebun Nasreen Ahmed
The base station can also be employed only for the specific support of Internet of Things (IoT), and in this regard, three competing platforms, namely, Sigfox, Long Range (LoRa), and Narrowband Internet of Things (NB-IoT) have become popular. Here, Sigfox and LoRa are two proprietary technologies from companies whereas NB-IoT is the development from 3GPP as a feature of the conventional 4 G/5 G cellular system. All these technologies operate at low data rate and low power, and thus, match the requirements of most of the IoT devices. Sigfox and LoRa use unlicensed industrial, scientific, and medical (ISM) radio bands. On the other hand, NB-IoT is a feature of the conventional 4 G/5 G cellular system, and so, it uses the licensed bands. At present, NB-IoT is more expensive compared to Sigfox and LoRa (Mekkia et al., 2019). However, the cost of NB-IoT will gradually decrease, and it will emerge with many advantages (5G Americas, 2019). In-Building Solutions (IBS): The cellular service can be generated inside the building using an in-building solution (IBS). This is primarily used for large buildings, where proper wireless coverage can be very difficult with signal from the outside base station, due to heavy penetration losses. IBS can be of the following types (The HetNet Forum, 2013). Femtocells: Femtocells are very small cellular base stations, designed for use within residential buildings, and in small commercial buildings or premises.Picocells: Picocells are small cellular base stations, suited for small and medium-sized buildings and premises.Distributed Antenna System (DAS): DAS provides efficient distribution of wireless connections inside large buildings, by routing signals through cables, from a single small base station to multiple antennas, located throughout the building.Small Source in the Building: A number of solutions exist, which use small devices to generate wireless service in the building. However, these small devices are often connected to the outside cellular base stations, for backhaul. These solutions include Wi-Fi, Zigbee, Bluetooth, Z-Wave, and Thread (Pradeep et al., 2016). These solutions differ in their capabilities, costs, and popularities. Besides, WiGig is introduced for a very high data rate and it uses high frequency, which is around 60 GHz (Chakkravarthy et al., 2019).