Several textbooks exist either on mobile networks or on (packet) networking, but separately, and they usually consider their subjects in isolation from each other. However, no mobile network exists without a related transport network connecting the elements; and also, mobile networks are becoming more and more important ‘customers’ for many kinds of packet networks.
Therefore this book is about considering these two domains together, and about looking at mobile network and backhaul network interactions, and how these two domains should take each other into account, particularly in the new era of (fully) packet-based transport solutions.
Mobile backhaul, as shown in Figure 1.1, is at the intersection of a mobile network and a transport network. Some aspects are more closely related to the radio network. Another area originates from the transport and networking side.
Figure 1.1 Mobile backhaul.
Usually mobile networks, radio interfaces, and other radio related topics are discussed within a circle of radio communication experts, without considering so much the other parts of the whole network. As an example, the 3GPP view of the transport connection between any two mobile network elements is a single, straight line. This very high level of abstraction serves focusing on the mobile network specific issues. However, when transport connections in real life are more complex, and in the era of packet networks very much more complex, different types of issues start to appear; functionalities and especially performance of the mobile network are impacted. The influence can in some cases be significant.
Correspondingly, it is not that easy for a networking expert to delve into the details of mobile network – even the fundamental concepts may be hidden into a number of mobile network standards. Also, 3GPP mobile networks, and their radio interfaces are not at all like a wireless LAN: their protocols are not based on Ethernet (which one could feel familiar with), and there is more of protocol layering and a division of functionality between mobile elements; simply put, they are more complex.
Therefore, if your background is in radio communication and mobile network, you will benefit from having an understanding of how the backhaul is built and how it influences the actual behavior and performance of the mobile network. For example, end-user bit rates are not limited only by the radio interface, but also by backhaul links, and thus it is becoming more important to understand and take into account the backhaul solutions applied.
On the other hand, if you are an IP and networking expert, you can use your competence more effectively when you understand more of the internal workings of the radio network side, and the basic requirements of radio networks relating to connections. Even if mobile backhaul is not the main driver for the networking industry, innovative solutions are needed to provide economic connections for advanced mobile networks and their services and data volumes, for example to cope with the high peak rates of HSPA+ and LTE networks.