rty OSS approaches and to provide a common platform to the operators, vendors, soft- ware developers and system integrators. We will start by providing some background info on OSS, describe the role of different SDOs and then provide details of Next Generation OSS (NGOSS). We will also provide information on how UMTS/EPS and WiMAX are using ITU-T and TM Forum stan- dards in addition to their respective 3GPP and IEEE management specifications in order to manage networks. Core Network Core network is that piece of the network that on one side is connected to the RAN and on the other provides connectivity to the outside world. The key core networks aspects that are part of 3GPP, 3GPP2, WiMAX, and MBWA are discussed in this section. Next Generation Mobile Communications Ecosystem: Technology Management for Mobile Communications Saad Z. Asif © 2011 John Wiley & Sons, Ltd. ISBN: 978-0-470-74746-9 Next Generation Mobile Communications Ecosystem GSM Base Station Mobile Station Subsystem (GSM BSS) CS Domain PS Domain UTRAN Radio Network lu-ps Mobile Station Subsystem (UTRAN 3GPP R99 Core Network Figure 8.1 3GPP Rel 99 core network architecture. Reproduced from Willie © 2002 John Wiley and Sons, Ltd [1] 8.2.1 3GPP Core Network The 3GPP core network has been evolved over the last many years via specifications that were completed in its different releases. The 3GPP specifications that were part of Releases 99 to 8 have been frozen¹ while Releases 9-10 are still in progress. 8.2.1.1 Rel '99 The R99 inherits a lot from the GSM model on the core network side. The R99 enabled WCDMA voice and data system and was functionally frozen in March 2000. The core network of R99 is an evolution of GSM core network which is based on MAP (Mobile Application Part). In 3GPP R99 the core network is divided into two distinct domains: the circuit switched (CS) domain and the packet switched (PS) domain. Generally, the PS domain is more efficient for packet data communications while CS is more preferred for voice services (Figure 8.1). The CS dom