MOBILE BACKHAUL

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Foreword
In the last few years we have seen an explosion of traffic on mobile networks as more and moreof our communication has become mobile. Today, many of the world’s most advanced mobilenetworks struggle to meet the performance and cost requirements placed on them and theytypically respond by investing heavily in technologies such as HSPA+ and LTE to increase thecapacity of the air interface. What cannot be ignored in the end-to-end architecture of mobilenetworks is the transport that plays a major role in determining the overall performance andcost of such networks. It is in this context that hardly any title could be more topical thanMobile Backhaul.The natural cycle of technology evolution and rapid replacement of legacy networks bymore capable and efficient packet networks further complicate the transport strategiesemployed by service providers. As the benefits of past investments compete with the capacityand efficiency of new investments, the result is an environment where multiple technologiesco-exist.In addition, packet based communication poses technical challenges that are not straightforward to overcome. Not all packet technologies can be applied to mobile backhaul and acareful examination of the underlying technology is required to ensure the integrity of theoverall system and its ability to meet specific requirements. Two relevant examples arequality of service and security. IP networks behave very differently in these two domainswhen compared with the legacy networks based on E1’s. Additionally, mobile networkscreate specific issues for the backhaul. A relevant example here is the need forsynchronization in a mobile environment in order to enable handover of users fromone base station to another and prevent interference, however, IP networks were notoriginally designed with these requirements in mind and need modifications to handlesuch requirements appropriately. Similarly, in an IP environment the delivery of allpackets is not guaranteed and this lack of guarantee poses challenges for mobilecommunication. Other technical and non-technical challenges also exist in buildingbackhaul networks which when taken together, lead us to conclude that a commonrule for building advanced backhaul networks capable of adequately handling manysimultaneous requirements is impossible to find. At the end, every network has to bespecified and deployed as a unique solution.The book you’re holding now does a great job in discussing these topics and reviewing andassessing technologies and possible solutions that are available either in the mobile network orin the packet network domains. Many innovations are known to be the result of combiningmultiple disciplines and this is exactly what the authors and editors of this book have done.
                                               Hossein MoiinChief Technology and Strategy OfficerNokia Siemens NetworksEspoo, Finland