## 4 Wireless Access for IoT Applications  
Wireless access networks for IoT applications span different geographic ranges, as shown in Figure 2[4]. Wireless personal area networks (WPANs) based on radio frequency identification (RFID) and near field communication (NFC) are the near-me area network type communication networks for devices in close proximity.  
WPANs are used to convey information over short distances among the group of participating devices with little or no infrastructure. These networks can be connected to cloud platforms through a centralized device or server. Most of theWPANs are designed for low data rate, power efficiency, and short distance, and are meant to be inexpensive solutions. ProminentWPAN technologies include IEEE 80.15.4 low rateWPANs, ZigBee, WirelessHart, ISA100.11a, 6 LoWPAN, Wibree, Bluetooth low energy (BLE), Insteon, Wavenis, Z-wave, ANT+, Enocean, and CSRMesh.  
Wireless local area networks (WLANs) are primarily designed for high speed data exchange between the devices with campus-wide coverage limited to a few hundred meters. WLAN technologies include the different flavors of the IEEE 802.11 standard. In addition, wireless neighborhood area network (WNAN) has evolved as a new architectural system for broadband wireless local distribution applications, which comprise of a service area smaller than metropolitan, but larger than local area networks. It can be used for residential, campus, and street-level environments for utility and smart grid applications. The technologies for WNAN are Wi-SUN, ZigBee NAN, and Wireless M-bus.  
Wireless wide area networks (WWANs) are designed to cater to larger areas compared with WLANs and WNANs. They have different requirements for different applications in terms of coverage, power efficiency, data rates, scalabilities, resource reuse, and others. WWANs can be broadly classified into cellular and LPWANs. Cellular networks such as 3G and 4G are primarily designed to transfer data at a high rate for a few to tens of kilometers. These networks support mobility, and hence provide extended coverage beyond the range of a single cell via handover mechanisms. LPWANs are the wireless communication technologies designed to allow long range communications with low power  
Figure 1: Application requirement attributes.  
consumption, low cost interface, and a relatively low bit rate for IoT and M2M applications. LPWAN is a major segment of IoT-based applications that span a long distance and are sensitive to both cost and power consumption. It is estimated that one-quarter of overall IoT/M2M devices will be connected to the Internet using either proprietary or standard LPWAN technologies. LPWAN solutions typically involve a massive number of end devices, send small-sized infrequent messages, and are tolerant of reasonably long end-to-end delays. Reliability requirements vary depending upon the application. LPWAN technologies complement and sometimes supersede the conventional cellular and short-range wireless technologies in performance for various emerging applications [6].  
Most of the intelligent applications will require some combinations of the above wireless access solutions.