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Spectrally Efficient Frequency Division Multiplexing (SEFDM) systems offer significant bandwidth gains at the expense of receiver complexity. While Maximum Likelihood (ML) and Sphere Decoding (SD) yield optimum performance, these techniques suffer from an impractical computational complexity. Previous work has shown that hybrid detectors combining Truncated Singular Value Decomposition (TSVD) with...
The proposal of Spectrally Efficient Frequency Division Multiplexing (SEFDM) system has added a new dimension for enhancing spectral utilization. SEFDM systems defy the orthogonality principle defined for Orthogonal Frequency Division Multiplexing (OFDM) systems by employing closely packed overlapped subcarriers to save bandwidth. Nevertheless, the loss of orthogonality results in intercarrier interference...
Simulation, using a model of a system or process, is widely accepted as a method of qualification and evaluation of complex systems. The success of a simulation depends on the accuracy of user defined values used to model parameters, which are gathered by analytical or empirical methods. In situations where some parameters are unknown or difficult to quantify, it is required to perform those operations...
This paper describes a digital circuit capable of performing sub-nanosecond phase shifting over a wide range of clock frequencies. In this circuit metastability phenomena and clock jitter generate glitches during the down-converted digital clock state transitions. In the work reported here, such glitches are removed using three deglitching techniques described in the paper. The phase shifter is implemented...
In this paper, a system architecture designed to distribute radio frequency (RF) signals in an Ethernet-based network is proposed. The Ethernet is the physical layer of the White Rabbit (WR) network. The WR network aims to distribute timing signals with sub-nanosecond accuracy. It is based on the IEEE 1588 and Synchronous Ethernet standards to allow rapid deployment for a broad range of applications...
Current trends in low-cost and low power consumption transmitters in state-of-the-art wireless systems is to use the direct-conversion principle. Such transmitters, however, suffer severely from the I/Q imbalance effect, which introduces mirror-frequency interference and degrades data detection. This paper proposes a novel method for frequency-dependent I/Q imbalance estimation and compensation. The...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) system employs non-orthogonal multiple carriers in order to enhance utilization of bandwidth over the Orthogonal Frequency Division Multiplexing system (OFDM). However, the deliberate loss of orthogonality affects many aspects of the system. In particular, the intercarrier interference results in the system becoming ill-conditioned, thus...
For research and development in computationally intensive bandwidth efficient Frequency Division Multiplexing (FDM) systems, it is generally preferable to implement test systems in hardware. This has the benefit of speed improvement over simulation and enables the generation and evaluation of real signals. This paper describes a system implementation of a versatile signal generator featuring high...
Spectrally efficient FDM (SEFDM) systems employ non-orthogonal overlapped carriers to improve spectral efficiency for future communication systems. One of the key research challenges for SEFDM systems is to demonstrate efficient hardware implementations for transmitters and receivers. Focusing on transmitters, this paper explains the SEFDM concept and examines the complexity of published modulation...
The Razor dynamic voltage scaling approach uses in situ error-detection and correction of timing errors to reclaim safety margins for improved energy-efficiency in digital circuits. In this paper, we propose the use of a time borrowing window on critical logic paths, over which timing errors can resolve safely without an explicit replay mechanism. We demonstrate that time borrowing can be incorporated...
Ethernet is synonymous with networking and its application is ubiquitous worldwide. Its popularity is in part due to its high bandwidth over long cable lengths and a driver-less architecture within an operating system environment. Communication over Ethernet has associated complexity, both in terms of the physical hardware the networking stack interface requirements. Hence, it is of great interest...
This work presents the hardware design of a novel algorithm using Field Programmable Gate Arrays (FPGAs) for the detection of Spectrally Efficient Frequency Division Multiplexing (SEFDM) signals. Previous work has shown that a sub-optimal Truncated Singular Value Decomposition (TSVD) approach is well-suited for use in SEFDM systems. TSVD offers a targeted reduction in complexity while outperforming...
Field Programmable Gate Arrays (FPGA) offer a unique combination of software abstraction and hardware performance, enabled by programming languages such as VHDL or Verilog. Inherent from this capability is a multitude of different design possibilities for a single implementation problem. A system can be designed which allows for real world evaluation at real time speeds of algorithms ordinarily restricted...
Spectrally Efficient FDM (SEFDM) systems employ non-orthogonal overlapped carriers to improve spectral efficiency for future communication systems. One of the challenges for SEFDM systems is to demonstrate efficient hardware implementations for transmitters and receivers. This paper presents the first VLSI digital baseband transmitter architecture for SEFDM. The transmitter is reconfigurable between...
The IEEE 802.16 is a series of telecommunication standards that provides Broadband Wireless Access (BWA) services and has received great attention worldwide. The IEEE 802.16j emerged as a standard in the middle of 2009, specifying the procedure of supporting Mobile Multi-hop Relay (MMR) networks. The use of the “multi-hop” architectures not only requires a re-design of the functional implementations...
Spectrally efficient FDM (SEFDM) systems are new and attractive multicarrier systems that can significantly enhance spectral utilization. However, as a multicarrier system SEFDM is prone to high peak to average power ratio (PAPR). In this work we present for the first time a study of the PAPR in SEFDM systems. We explore the performance of standard PAPR reduction techniques and propose a novel PAPR...
Spectrally Efficient FDM (SEFDM) signals employs non-orthogonal and overlapping carriers to provide higher spectrum utilization relative to Orthogonal FDM signals (OFDM). Complex detectors are employed to extract the signal from the intercarrier interference (ICI) created by the loss of orthogonality. Sphere Decoder (SD) is proposed for SEFDM detection as an algorithm that achieves ML bit error rate...
We describe a network architecture for bidirectional transfer of information in the upgraded design of the Large Hadron Collider at CERN. Special requirements imposed by the application lead to a non-conventional network design compared to commercial telecommunication networks. The main factors driving the design are the highly asymmetric and upstream-intensive traffic and the requirement for low...
In this paper, we present a novel circuit-level timing error mitigation technique, which aims to increase energy-efficiency when applying a known in situ error-detection and correction technique, called Razor, to DSP datapaths. Timing errors are detected using Razor flip-flops at critical-path endpoints and the error-rate feedback is used to control a dynamic voltage scaling (DVS) control loop. We...
This paper investigates the transmission in time dispersive channels of Spectrally Efficient Frequency Division Multiplexed (SEFDM) signals, where carrier orthogonality is intentionally violated in order to increase bandwidth efficiency. Sufficient statistics of the transmitted SEFDM signal can be obtained by projecting the received signal onto an orthonormal base generated at the receiver using an...
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