Mobile Systems Development - A literature review <s> Wireless communications <s> A mobile ad hoc network (MANET) consists of mobile nodes communicating over wireless channels. Routing in MANETs is very challenging due to the random mobility of nodes and unreliability of wireless channels. Therefore most of the existing routing algorithms make only the best effort to find routes for communication but do not provide any performance guarantee. Because of the widespread use of MANETs in real-time applications, it becomes pertinent to provide deterministic network behavior. Quality of Service (QoS) aims to shape the network behavior and provide performance guarantees. In this work, a novel heuristic called Advanced-Optimised Link State Routing (A-OLSR) protocol is designed to provide QoS. It functions by enhancing the connectivity of nodes and establishing more stable routes as compared to standard best-effort Optimised Link State Routing (OLSR) protocol. The simulation results show that A-OLSR provides lower delay, reduces energy consumption and achieves higher throughput without introducing any additional routing overhead as compared to the standard OLSR and it's variants-A$$'$$?-OLSR and A$$''$$??-OLSR. The results also show that A-OLSR provides scalability since it's performance remains consistent with the increasing size of network. <s> BIB001 </s> Mobile Systems Development - A literature review <s> Wireless communications <s> In overlaying an existing cdma2000 network with a UMTS network, service transparency and number portability are important requirements for end users and hence the network operator. To support both requirements, one could introduce a protocol conversion node between the two networks; however, such a solution does not fully meet the requirements due to inherent technical constraints imposed by the differing standards. This article describes a network architecture based on the dual stack concept that satisfies the service transparency and number portability requirements across UMTS and cdma2000 networks, and also defines the functionality of the network nodes and the call processing procedures. <s> BIB002
In this context wireless communications covers research on or strongly related to cellular systems and network infrastructure. The increasing number of new or improved wireless network technologies is immense. The primary challenge is therefore not any longer just to go wireless, but seem to be "the ability to provide seamless and adaptive quality of service in such a heterogeneous environment" (Gao, Wu et al. 2004, p. 24) . Currently, this field seems to attract particular interest both in practice and in research. Examples of some the latest contributions are: BIB001 discuss the challenges of mobile ad hoc networks (MANETs) and future directions and challenges, BIB002  ) present challenges and solutions in an attempt to solve the interoperability problems in the UMTS network,  propose a framework for integration of cellular wide wireless area networks (WWAN) and wireless local area networks (WLAN), and    ) attacks the challenges associated with turning the 4G platform into an open architecture including different wireless networks.