Teaching telecommunication standards: bridging the gap between theory and practice

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Telecommunication standards have become a reliable mechanism to strengthen collaboration between industry and research institutions to accelerate the evolution of communications systems. Standards are needed to enable cooperation while promoting competition. Within the framework of a standard, the companies involved in the standardization process contribute and agree on appropriate technical specifications to ensure diversity and compatibility, and facilitate worldwide commercial deployment and evolution. Those parts of the system that can create competitive advantages are intentionally left open in the specifications. Such specifications are extensive, complex, and minimalistic. This makes telecommunication standards education a difficult endeavor, but it is much demanded by industry and governments to spur economic growth. This article describes a methodology for teaching wireless communications standards. We define our methodology around six learning stages that assimilate the standardization process and identify key learning objectives for each. Enabled by software-defined radio technology, we describe a practical learning environment that facilitates developing many of the needed technical and soft skills without the inherent difficulty and cost associated with radio frequency components and regulation. Using only open source software and commercial of-the-shelf computers, this environment is portable and can easily be recreated at other educational institutions and adapted to their educational needs and constraints. We discuss our and our students' experiences when employing the proposed methodology to 4G LTE standard education at Barcelona Tech.Peer ReviewedPostprint (author's final draft

A practical approach to cellular communications standards education

The cellular communications industry is steadily growing and expanding to solve the needs of governments, businesses and communities. Standards are fundamental to enable cooperation while promoting competition. The companies involved contribute and agree on appropriate technical specifications to ensure diversity, compatibility and facilitate worldwide commercial deployment and evolution. The specifications of cellular communications standards are extensive, complex and intentionally incomplete to spur innovation and differentiation. This makes standards education a difficult endeavor, but it is highly demanded by the wireless industry. This paper describes a practical approach to teaching cellular communications standards. Our methodology leverages software-defined radio technology and uses the abstraction layer and operating environment (ALOE) to provide a practical learning environment that facilitates developing many of the needed technical and soft skills without the inherent difficulty and cost associated with radio frequency components and regulation. We define six learning stages that assimilate the standardization process and identify key learning objectives for each. We discuss our experiences when employing the proposed methodology at Barcelona Tech in Spain, compare the approach with an equivalent class at Virginia Tech in the US and make the following observations: (1) The complexity of standards need to be abstracted and presented in a form suitable for a given class. (2) Educating about cellular communications standards is most effective when students are immersed in the process. (3) Hands-on activities need careful preparation and close guidance.Peer ReviewedPostprint (published version

Performance of soft-output equalization and convolutional coding over frequency-selective fading radio channels

This paper presents an analysis of soft-output equalization and coding techniques applied to 4 and 16-QAM TDMA radio systems for frequency selective fading channels. In particular, typical urban and hilly terrain environments have been considered. The use of the soft information provided by the equalizer enhances the system performance considerably. Specifically, an improvement of more than 4 dB can be achieved in relation to hard decoding techniques. The necessity of introducing some interleaving in order to destroy the channel memory has also been stated. The actual investigated equalizers have been a soft-output decision-feedback equalizer (SODFE) and a soft-decision M-algorithm (SDMA) jointly with convolutional coding and both ideal and finite interleaving.Peer ReviewedPostprint (published version

Deployment and management of SDR cloud computing resources: problem definition and fundamental limits

Software-defined radio (SDR) describes radio transceivers implemented in software that executes on general-purpose hardware. SDR combined with cloud computing technology will reshape the wireless access infrastructure, enabling computing resource sharing and centralized digital-signal processing (DSP). SDR clouds have different constraints than general-purpose grids or clouds: real-time response to user session requests and real-time execution of the corresponding DSP chains. This article addresses the SDR cloud computing resource management problem. We show that the maximum traffic load that a single resource allocator (RA) can handle is limited. It is a function of the RA complexity and the call setup delay and user blocking probability constraints. We derive the RA capacity analytically and provide numerical examples. The analysis demonstrates the fundamental tradeoffs between short call setup delays (few processors) and low blocking probability (many processors). The simulation results demonstrate the feasibility of a distributed resource management and the necessity of adapting the processor assignment to RAs according to the given traffic load distribution. These results provide new insights and guidelines for designing data centers and distributed resource management methods for SDR clouds.Peer ReviewedPostprint (published version

Dynamic resource allocation in software-defined radio - The interrelation between platform architecture and application mapping

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Software radios: unifying the reconfiguration process over heterogeneous platforms

Future radio transceivers supporting the software radio concept will provide increased features for radio access networks. However, the reconfiguration of radio equipment requires the existence of architecture, a common framework, which allows the flexible management of software running on radio processors. Such a framework must take into account the heterogeneity of hardware devices and platforms for radio applications. Since the flexibility has a cost in terms of added overhead, a conceptually simple but efficient structure that allows powerful mechanisms to develop and deploy software radio applications is required. This paper describes our approach, the reasons that motivated it, and some implementation issues. The proposed framework is essentially based on four items: an abstraction layer which hides any platform-dependent issue, a simple time-driven software structure, a delimited interface format for software blocks which does not actually constrain communication, and a global time-reference mechanism to guarantee real-time behavior.Peer Reviewe

Design and implementation of a wide-band real-time mobile channel emulator

A new wide-band mobile channel emulator for the CODIT project is designed and implemented. The UMTS code-division testbed (CODIT R2020) is a research project within the European RACE-II program set up by the Commission of the European Community. Our goal is to be able to simulate in the laboratory, in real time, the multipath propagation found in the mobile radio channel. As code-division multiple access (CDMA) is the access technique within the CODIT project, it was realized that the channel emulator must have simultaneously good delay resolution between propagation paths and long duration of the impulse response. These considerations led to a very flexible channel emulator specifically designed to host the new wide-band channel models developed within the CODIT project. Our emulator features three independent inputs and two outputs, up to 20 complex propagation paths, 10-MHz radio frequency (RF) bandwidth, a delay resolution of 50 ns, and a maximum duration of the channel impulse response of 80 μs. Starting with an explanation of the global structure of the new channel emulator, we derive the optimum design of the interpolation procedures and present the main implementation issues arising from our initial architecture. Finally, we report the results of the laboratory tests of the first prototype of the channel emulator.Peer Reviewe

Open source software radio platform for research on cellular networked UAVs: It works!

Cellular network-connected unmanned aerial vehicles (UAVs) experience different radio propagation conditions than radio nodes on the ground. Therefore, it has become critical to investigate the performance of aerial radios, both theoretically and through field trials. In this article, we consider low-altitude aerial nodes that are served by an experimental cellular network. We provide a detailed description of the hardware and software components needed to establish a broadband wireless testbed for UAV communications research using software radios. Results show that a testbed for innovation in UAV communications and networking is feasible with commercial off-the-shelf hardware, open source software, and low-power signaling.This work was in part supported by NSF award CNS-1939334.Peer ReviewedPostprint (author's final draft

A real time emulator of the UMTS lower layers for the wineglass demonstrator

In this paper, a general description of the main features of a Real Time Emulator, which emulates the lower layers of the UMTS Radio Access system, is presented. For the physical layer, the emulation model is based on the concept of the Hidden Markov Model. Layer 2 functionality is emulated by means of ad-hoc C++ software, whereas the RRM functionality is statistically described.Peer ReviewedPostprint (published version

SDR in undergraduate engineering education

Postprint (published version