## 3 Fixed Wireless Access  
In Section 2.1, we discussed different fixed-line broadband technologies. This section focuses on the broadband wireless scheme features, design considerations, challenges, and viable solutions. Broadband wireless is based on exploiting the inherent advantages of wireless technologies in offering a broadband experience with a variety of unique benefits to the subscribers. Basically, broadband wireless can be categorized into fixed wireless broadband and MBB. The former tries to deliver many services that are similar to the one offered by the traditional fixed-line broadband while employing a wireless transmission medium. Consequently, it can be seen as a good alternative to the cable modem or DSL. In addition, the latter presents additional features, such as nomadicity, portability, and mobility [159]. The FWA is based on the notion of broadband services (internet access, voice, and video) provision to the households and Small and Medium-sized Enterprises using wireless mobile network technologies instead of cable or fixed-line systems [8, 239, 240, 241, 230, 242, 243, 244, 24] as discussed in Section 2.1. In FWA technology, an access unit attached to the street or parking sign connects wirelessly to an Rx being deployed in the subscriber property. At that point, the Rx feeds a router that offers a wireless signal in the building [4]. This concept is more desirable in scenarios where no infrastructure is available for delivering wired broadband service through fiber, copper, or hybrid schemes. FWA also finds applications in a situation where the existing infrastructure is inadequate and/or underperforming. In essence, FWA offers the providers the opportunity of delivering faster network connectivity to subscribers that need an upgrade and also help in extending high-speed broadband services to regions without access to the existing fixed-line broadband network [8, 240, 242, 243, 244, 245, 246, 247, 248]. As a result of this, the potential of ubiquitous FWA emerges considerably with each generation of wireless mobile technology discussed in Section 2.3. Moreover, one of the salient features of mobile technology generations is the support for network convergence. This helps in delivering both fixed and MBB access using the same technologies and shared infrastructures. For instance, FWA could be helpful in the LTE and LTE-A networks as an add-on enhancement to the MBB. Moreover, with LTE evolutions, the implementation happens to be stronger. Note that there have been notable concerns about the related costs and performance issues of the earlier FWA system compared to the fixed-line broadband system. For instance, the present mobile system cannot match either the latency levels or download speeds of the modern fiber broadband connection [6, 249]. This is because the WiMAX-based system can deliver tens of Mbps speed services, while the LTE-based system can provide tensto hundreds of Mbps. On the other hand, the 5G-based system is envisaged to offer Gbps speed services, resulting in fiber-like user experience [48; 249]. The outstanding improvement will be partly due to the advanced multi-antenna technologies that would be exploited [10; 84; 86; 88; 89; 90]. It is remarkable that, MIMO schemes can help in achieving broader coverage in the 5G network [250]. For instance, the capacity of \(N_{r}\times N_{t}\) MIMO scheme can be expressed as [165; 251; 252]  
\[ \begin{split} C&=\log_{2}\biggl{[}\det\biggl{(} \mathbf{I}_{N_{r}}+\frac{\gamma_{k,j}}{N_{t}}\mathbf{H}\mathbf{H}^{\dagger} \biggr{)}\biggr{]}\mathsf{b}/\mathsf{s}/\mathrm{Hz}\\ &=\sum_{i=1}^{\min(N_{t},N_{r})}\log_{2}\biggl{(}1+\frac{\gamma_{ k,j}}{N_{t}}\lambda_{i}\biggr{)}\mathsf{b}/\mathsf{s}/\mathrm{Hz}\end{split}