Multimedia Internet of Things: A Comprehensive Survey <s> VII. PHY-MAC PROTOCOLS FOR M-IoT <s> This chapter provides insights into the structure and services provided by each layer of the ZigBee and IEEE 802.15.4 standards. The protocol layers cooperate with each other to perform various tasks, such as joining a network or routing messages. This chapter reviews the concept of service primitives, which is a convenient way of describing protocol services, focusing on functional descriptions of services provided by each protocol layer. It also offers details on subjects such as frame formats. There are seven layers in the ISO/OSI model, but ZigBee implements only the layers that are essential for low-power, low-data rate wireless networking. Each layer communicates with the adjacent layers through service access points. The IEEE 802.15.4 not only specifies the PHY protocol functions and interactions with the MAC layer but also defines the minimum hardware-level requirements, such as the receiver sensitivity and the transmitter output power. These specifications include channel assignments, energy detection, carrier sense, link quality indicator, and clear channel assessment. The MAC provides the interface between the PHY and the next higher layer above the MAC. In ZigBee wireless networking, this next higher layer is the NWK layer. The IEEE 802.15.4 is not developed specifically for ZigBee applications, and the next higher layer can be any networking protocol layer. This chapter discusses the MAC services in interfacing with the ZigBee NWK layer. Finally, it reviews the security services in ZigBee standards, which support the use of encryption and authentication protocols. <s> BIB001 </s> Multimedia Internet of Things: A Comprehensive Survey <s> VII. PHY-MAC PROTOCOLS FOR M-IoT <s> Low Rate Wireless Personal Area Networks (LR-PAN) such as sensor networks have become very popular in recent years. These networks can be implemented with little or no infrastructure. The first step of standardization for such LR networks was taken in 2003 when the IEEE 802.15.4 was approved. This standard however went through an enhancement process and a newer version was released in 2006 known as the IEEE 802.15.4–2006 (or 802.15.4b) standard. However neither of the two standards supported ranging capabilities between nodes in the network. In order to support distance and hence location information, the IEEE 802.15.4–2007 was approved (also known as 802.15.4a). Standardization process continued and newer standards such as the IEEE 802.15.4c and 4d were sanctioned very recently. This paper reviews the network topologies, physical and MAC layers of the IEEE 802.15.4 family. <s> BIB002 </s> Multimedia Internet of Things: A Comprehensive Survey <s> VII. PHY-MAC PROTOCOLS FOR M-IoT <s> Wireless Personal Area Networks (WPANs) are an emerging technology for future short-range indoor and outdoor multimedia and data centric applications. Two types of WPANs have been standardized by the IEEE 802.15 working group; namely: High data Rate WPANs (HR-WPANs) and Low data Rate WPANs (LR-WPANs). These standards define the network architecture, the physical layer and the medium access control sublayer for these systems. A tremendous number of performance studies through mathematical analysis and simulation have been published. Also, many products have appeared in the market which indicate a clear sign of a quick acceptance to the published standards. An organized review of the network architecture, the physical layer specifications, the Medium Access Control (MAC) protocols and the general network operation concepts of the WPAN systems deserves time and effort to be presented in a collective manner. In this paper we describe the concept of WPANs and its applications. Then, the communication architecture and the allocated frequency spectrum for WPAN operation are explained. The developed MAC sublayer protocols in the literature are explored. <s> BIB003 </s> Multimedia Internet of Things: A Comprehensive Survey <s> VII. PHY-MAC PROTOCOLS FOR M-IoT <s> Wireless Multimedia Sensor Networks (WMSN) have recently gained the attention of the research community due to their wide range of applications and the advancement of CMOS cameras. In this survey paper we outline the WMSN applications, discuss their challenges and resource constraints. In addition, this paper investigates the proposed solutions by the research community to overcome challenges and constraints through architecture design and multimedia encoding paradigms. Moreover, some of the deployed examples of WMSN done by different research groups are also discussed. In addition, we provide a detail discussion of the proposed optimization solutions and outline research areas of possible improvements. <s> BIB004 </s> Multimedia Internet of Things: A Comprehensive Survey <s> VII. PHY-MAC PROTOCOLS FOR M-IoT <s> Internet of Things (IoT) is a fast-growing innovation that will greatly change the way humans live. It can be thought of as the next big step in Internet technology. What really enable IoT to be a possibility are the various technologies that build it up. The IoT architecture mainly requires two types of technologies: data acquisition technologies and networking technologies. Many technologies are currently present that aim to serve as components to the IoT paradigm. This paper aims to categorize the various technologies present that are commonly used by Internet of Things. <s> BIB005 </s> Multimedia Internet of Things: A Comprehensive Survey <s> VII. PHY-MAC PROTOCOLS FOR M-IoT <s> This paper focuses on the the emerging transmission technologies dedicated to IoT networks. We first analyze the classical cellular network technologies when taking into account the IoT requirements, and point out the need of dedicated technologies for IoT. Then, we present the PHY and MAC layers of the technologies that are already deployed, or likely to be deployed: UNB by SigFox, CSS by LoRa T M , Weighless, and RPMA by Ingenu. We then compare their performances to highlight their pros and cons. Finally, we discuss on the open research challenges that still need to be addressed. <s> BIB006
The network protocol stack of the IoT architecture rests on the joint PHY-MAC layer as depicted in Fig. 16 . The protocols under this layer, feature low power operations and guarantee a stringent QoS compliant performance. The discussion of the M-IoT applications in the preceding sections indicates a general guideline for the design of the PHY-MAC protocols. These guidelines include an ability to manage a dense, as well as a sparse network, with a small network overhead, over a wide range and with a low energy requirement BIB006 . The applicability of M-IoT in the wide range of applications like industrial monitoring, healthcare, security, and smart services in smart city applications implies that there are multiple QoS and QoE parameters for each application. Additionally, the heterogeneity of the devices in the network creates a set of challenges in terms of interoperability. That results in a need for application-oriented data transformations at the network gateway BIB005 . Therefore, the PHY-MAC layer for each application is designed to fulfill these QoS and QoE parameters. This section discusses the different MAC-PHY standards and protocols designed for specific applications. The major standard in use today is the IEEE 802.15.4 that covers the physical layer specifications for the global application. It forms the basis of the ZigBee standard that is usually used in the smart living IoT scenarios. Additionally, the IEEE 802.15.6 standard is defined for the healthcare scenarios. The other standards used for specific application cases are BLE, Long Range Wide Area Network (LoRaWAN), NB-IoT, and Near Field Communication (NFC). These provide the physical layer as well as MAC specifications for the M-IoT networks. The IEEE 802.15.4 family of Low Rate Wireless Personal Area Networks (LR-WPANs) was first approved in 2003 BIB002 . Since then, several amendments have been made to the standard. There have been numerous regionspecific amendments as well as application-specific amendments in the 2003 approved standard. The features of the PHY-MAC standards, along with the amendments, are tabulated in Table 9 . This standard supports both, a star topology as well as a peer-to-peer topology. The MAC layer resides above the PHY layer in the OSI model and provides an interface between the PHY and the higher layers BIB002 , BIB001 . The MAC specifications for the IEEE 802. 15.4 (2003 release) envisages the use of a Carrier Sense Multiple Access with Collison Avoidance (CSMA/CA) mechanism for Channel Access. The CSMA/CA supports the beaconed mode as well as the non-beaconed mode  , BIB003 . The CSMA/CA mechanism for this standard and the IEEE 802.11 differs due to the absence of a request to send/clear to send (RTS/CTS) frame exchange in the IEEE 802.15.4 family. Additionally, in the IEEE 802.15.4a-2007 amendment, the ALOHA is used for the channel access for the Ultra-Wide Band (UWB)  . The 802.15.4 standard serves as the PHY-MAC standard for a large range of applications which requires a unique approach to each problem such as in industrial systems. Additional applications include multimedia surveillance, traffic management, advanced healthcare, and environmental monitoring BIB004 . Therefore, the focus of this section remains the IEEE 802.15.4 standard as most of the M-IoT scenarios are operated by this standard. The application-oriented PHY-MAC approaches are discussed under the following sub-headings.