In computer networking, a heterogeneous network is a network connecting computers and other devices where the operating systems and protocols have significant differences. For example, local area networks (LANs) that connect Microsoft Windows and Linux based personal computers with Apple Macintosh computers are heterogeneous. Heterogeneous network also describes wireless networks using different access technologies. For example, a wireless network that provides a service through a wireless LAN and is able to maintain the service when switching to a cellular network is called a wireless heterogeneous network. HetNet Reference to a HetNet often indicates the use of multiple types of access nodes in a wireless network. A Wide Area Network can use some combination of macrocells, picocells, and femtocells in order to offer wireless coverage in an environment with a wide variety of wireless coverage zones, ranging from an open outdoor environment to office buildings, homes, and underground areas. Mobile experts define a HetNet as a network with complex interoperation between macrocell, small cell, and in some cases WiFi network elements used together to provide a mosaic of coverage, with handoff capability between network elements. A study from ARCchart estimates that HetNets will help drive the mobile infrastructure market to account for nearly US$57 billion in spending globally by 2017. Small Cell Forum defines the HetNet as ‘multi-x environment – multi-technology, multi-domain, multi-spectrum, multi-operator and multi-vendor. It must be able to automate the reconfiguration of its operation to deliver assured service quality across the entire network, and flexible enough to accommodate changing user needs, business goals and subscriber behaviours.’ HetNet architecture From an architectural perspective, the HetNet can be viewed as encompassing conventional macro radio access network (RAN) functions, RAN transport capability, small cells, and Wi-Fi functionality, which are increasingly being virtualized and delivered in an operational environment where span of control includes data center resources associated with compute, networking, and storage. In this framework, self-optimizing network (SON) functionality is essential to enable order-of-magnitude network densification with small cells. Self-configuration or ‘plug and play’ reduces time and cost of deployment, while self-optimization then ensures the network auto-tunes itself for maximum efficiency as conditions change. Traffic demand, user movements and service mix will all evolve over time, and the network needs to adapt to keep pace. These enhanced SON capabilities will therefore need to take into account the evolving user needs, business goals and subscriber behaviors. Importantly, functions associated with HetNet operations