Long Term Evolution (LTE) Tutorials
LTE video tutorial
Rohde & Schwarz's 14-part presentations provide an excellent introduction to LTE. The presentations start with a background on LTE. This is followed by lectures that cover LTE frequency bands, OFDM, OFDMA, SC-FDMA and LTE signaling. The lectures also cover channel mapping and UE categories.
LTE physical layer
LTE link layer design
This article describes the LTE link-layer protocols, which abstract the physical layer and adapt its characteristics to match the requirements of higher layer protocols.The LTE link-layer protocols are optimized for low delay and low overhead and are simpler than their counterparts in UTRAN. The state -of-the-art LTE protocol design is the result of a careful crosslayer approach where the protocols interact with each other efficiently. This article provides a thorough overview of this protocol stack, including the sub-layers and corresponding interactions in between them, in a manner that is more intuitive than in the respective 3GPP specifications.
Introduction to LTE architecture
This article provides an overview of the LTE radio interface, together with a more in-depth description of its features such as spectrum flexibility, multi-antenna transmission, and inter-cell interference control. The performance of LTE and some of its key features is illustrated with simulation results.
This article provides a high-level overview of LTE and some of its key components: spectrum flexibility, multi-antenna transmission, and ICIC. Numerical simulations are used to show the performance of the first release of LTE, as well as assess the benefit of the key features. Indeed these contribute strongly to LTE meeting its performance targets. An outlook of the evolution of LTE toward LTE-Advanced and full IMT-Advanced capabilities complete the article. Clearly, LTE offers highly competitive performance and provides a good foundation for further evolution.
LTE and LTE Advanced presentations
LTE protocol architecture
This paper describes the system architecture and performance objectives of LTE. The role of different functional elements and their interfaces are covered. The article also discussed the uplink and downlink channel types. The article also covers mobility management in LTE.
LTE network architecture
This paper provides a short, but comprehensive, overview of the LTE network architecture and interfaces. The paper introduces control plane and user plane architecture. LTE procedures on S1 and X2 interfaces are described in detail. The paper also briefly touches the bearer establishment procedure.
EPS architecture overview
This excellent video by Russell DeLong covers the EPS in detail. The topics covered here are:
Terminology clarifications for "4G LTE" and the EPS.
Overview of each component of EPS. Russell walks you through the role of the MME, the S-GW and the P-GW.
Overview of each logical connection between each component on the EPS.
LTE channels and performance
In this paper, an overview of the air interface for LTE E-UTRA with system performance results is provided. It is shown that LTE E-UTRA system performance can achieve 3-4x improvement over HSDPA and HSUPA with receiver diversity. LTE EUTRA uplink performance improvement relative to HSUPA was achieved without using any MIMO, interference suppression, or larger TTI and was mainly due to orthogonality and ability to use narrow band transmissions for coverage limited situations. In the downlink, the performance gap in reaching the desired target range of 3-4x spectral efficiency and average user throughput can be met using MIMO techniques.
LTE channels and protocol layers
This paper provides an overview of the MAC for 3GPP™ Long Term Evolution (LTE) also referred to as E-UTRAN, with a focus on the handset or User Equipment (UE). The protocol stack functions consist of the Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Radio Resource Control (RRC).
LTE uses all the time on the downlink for conveying data; the downlink PHY is fully scheduled so there are no gaps due to arbitration or contention except for the initial access on the random access procedure. The downlink carries multiple logical channels over one link, so a lot of information is multiplexed together in one transport block, as opposed to other networks where any given packet is only carrying one type of information at a given time, such as in a control plane or a user plane..
LTE physical layer presentation
Dynamic radio resource management in LTE
Radio resource management attracts great attention while utilizing available resources to provide users with enhanced system throughput. Radio resources management include transmission power management, mobility management, and scheduling of radio resources. An intelligent radio resource management is at the heart of LTE to make it a robust technology to meet the broadband mobility needs of upcoming years. This will schedule the available resource in a best way and provide to the users with the enough transmission capability to achieve the decided QoS even while they move freely and also will make sure that these assigned resources would not interfere with already assigned resources. This will also be of interest that the transmitted signal will reach the receiver in a good health while utilizing the power efficiently available at the transmitter.
For over a decade universities and wireless research labs have been combining multiple antenna transmission techniques with advanced signal processing algorithms to create what is sometimes called smart-antenna and is also known as multi-input multi-output (MIMO) technology. These schemes are now moving into mainstream communication systems. Indeed, MIMO technologies can already be found in wireless local area network access points (e.g. 802.11n based solutions). This has led to MIMO being standardized in WiMAX as well as in 3GPP Rel-6 and Rel-7 of the UTRAN (HSPA) specifications. Further, Rel-8 of the E-UTRAN (LTE) 3GPP specifications, completed in March 2009, included the most advanced forms of MIMO in any standard in the industry. And even more advanced MIMO enhancements are currently being studied for inclusion in 3GPP Rel-9 and Rel-10.
LTE signal visualization
LTE signal demonstration
LTE visualization tool
This tool is free to download and use. It models the allocation of downlink Resource Elements to the set of Signals and Physical Channels. The user can configure each of the variables which have an impact upon the allocation of Resource Elements, e.g. the channel bandwidth, number of transmit antenna and cell identity. The tool also quantifies throughput for each modulation scheme and a range of assumed coding rates.
LTE/LTE Advanced Networks - special issue
This special issue consists of five papers. The first three papers focus on LTE: there is a survey paper on resource scheduling and interference mitigation techniques, a paper on resource scheduling for the provision of different services, and a paper on a method for improving the tradeoff between service quality and radio coverage for enhanced multimedia broadcast and multicast service (E-MBMS). The other two papers are focused on LTE-A: one paper discusses distributed algorithms for solving two self-configuration problems and the other examines the performance of decode-and-forward relaying.
Voice over LTE
VoLTE video tutorial
Circuit switched fallback in LTE
LTE & Voice by chrisreece
Many networks use circuit switched fallback for setting up voice. When an LTE user makes a voice call, the mobile falls back to to UMTS. Pros and cons of CS fallback are also discussed.
Introduction to IMS
IMS will increasingly play a bigger role in next generation IP services. IMS will start with voice and move over to other services. IMS components and their interactions with LTE and voice networks are discussed.