Energy Harvesting Communications

5Upper Layer Techniques

5.1 Introduction

The upper layers refer to the layers in the communications model, as shown in Figure 4.1, that are immediately above the physical layer. In the open systems interconnection (OSI) model, these are the link layer that provides link control and the network layer that provides message routing. In the transmission control protocol/internet protocol (TCP/IP) model, they are the upper part of the network interface layer that provides link control and the internet layer that provides message routing. In both models, these layers are the layers that are the closest to the physical layer and therefore they have significant impact on the performances of transmission, detection and estimation in the physical layer. Thus, they will be considered in this chapter for energy harvesting wireless communications.

In the upper layers, the link layer provides control functions for the successful operation of the physical layer and sometimes, it is called the media access control (MAC) layer. These control functions or the MAC protocols coordinate the transmission and reception in the physical layer for each node by performing resource allocation and scheduling. For example, which user should be activated in multi‐user scheduling, which channel should be assigned in access control, and how long and how much power each user should use in duty cycle and power management. These functions are vital for the smooth operation of the physical layer. In energy harvesting ...