ng, Y. Chen, M. Al-Shalash, C. Caramanis, and J. G. Andrews, "User Association for Load Balancing in Heterogeneous Cellular Networks", IEEE Transactions on Wireless Communications, 12(6), 2706-2716 (2013). [9] 3GPP TS 36.423, 'X2 Application Protocol (X2AP)', v.12.2.0, June 2014. [10] 3GPP TS 36.101, 'User Equipment (UE) Radio Transmission and Reception', v.12.4.0, June 2014. [11] P. Szilagyi, Z. Vincze, and C. Vulkan, 'Enhanced Mobility Load Balancing Optimisation in LTE', Proc. 2012 IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC), 2012. Smartphone Optimization Rafael Sanchez-Mejias, Laurent Noël and Harri Holma 16.1 Introduction Smartphone Traffic Analysis in LTE Networks Smartphone Power Consumption Optimization Smartphone Operating Systems Messaging Applications 16.6 Streaming Applications Voice over LTE Smartphone Battery, Baseband and RF Design Aspects 16.9 Summary References 16.1 Introduction Smartphones are the main source of traffic in the mobile broadband networks. This chapter analyses the traffic patterns created by smartphones and focuses on the network optimization for the typical smartphone applications. Section 16.2 explains the main learnings about the traffic patterns from live LTE networks. The analysis covers user plane and control plane and can be used for network dimensioning. Section 16.3 illustrates the optimization of smartphone power consumption with carrier aggregation (CA) and with discontinuous reception. Section 16.4 presents the signalling traffic from smartphones with different operating systems (OSs) and applications. Messaging and streaming application optimization is considered in Sections 16.5 and 16.6. A number of different voice solutions are tested in Section 16.7 in terms of power consumption and bandwidth requirements. The smartphone design aspects are considered in Section 16.8 and the chapter is summarized in Section 16.9. LTE Small Cell Optimization: 3GPP Evolution to Release 13, First Edition. Edited by Harri Holma, Antti