Inversion of Parahermitian matrices

Parahermitian matrices arise in broadband multiple-input multiple-output (MIMO) systems or array processing, and require inversion in some instances. In this paper, we apply a polynomial eigenvalue decomposition obtained by the sequential best rotation algorithm to decompose a parahermitian matrix into a product of two paraunitary, i.e.lossless and easily invertible matrices, and a diagonal polynomial matrix. The inversion of the overall parahermitian matrix therefore reduces to the inversion of auto-correlation sequences in this diagonal matrix. We investigate a number of different approaches to obtain this inversion, and and assessment of the numerical stability and complexity of the inversion process

Dynamic reconfiguration technologies based on FPGA in software defined radio system

Partial Reconfiguration (PR) is a method for Field Programmable Gate Array (FPGA) designs which allows multiple applications to time-share a portion of an FPGA while the rest of the device continues to operate unaffected. Using this strategy, the physical layer processing architecture in Software Defined Radio (SDR) systems can benefit from reduced complexity and increased design flexibility, as different waveform applications can be grouped into one part of a single FPGA. Waveform switching often means not only changing functionality, but also changing the FPGA clock frequency. However, that is beyond the current functionality of PR processes as the clock components (such as Digital Clock Managers (DCMs)) are excluded from the process of partial reconfiguration. In this paper, we present a novel architecture that combines another reconfigurable technology, Dynamic Reconfigurable Port (DRP), with PR based on a single FPGA in order to dynamically change both functionality and also the clock frequency. The architecture is demonstrated to reduce hardware utilization significantly compared with standard, static FPGA design

Acceptability of mindfulness from the perspective of stroke survivors and caregivers: a qualitative study

Background: Depression is very common among stroke survivors with estimated prevalence rates of approximately 33% among stroke survivors, but treatment options are limited. Mindfulness-Based Stress Reduction (MBSR) is an effective treatment for depression generally, but benefits in stroke patients are unclear. The aim of this study was to determine the feasibility of delivering MBSR to stroke survivors and their caregivers in the community. We conducted a study to gain views of MBSR as a potential treatment option among stroke survivors and their caregivers in the community. Methods: Participants were recruited from an urban community in Scotland (UK) using newspaper adverts, social media and support groups run by health charities. A 2-h MBSR taster session was delivered by two experienced mindfulness instructors, followed by focus group sessions with all participants on their user experience and suggestions for MBSR modifications for stroke survivors. The focus group sessions were audio recorded and transcribed verbatim. Transcript data were analysed thematically using the framework approach. Results: The study sample consisted of 28 participants (16 females); there were 21 stroke survivors (11 females) and 7 caregivers (5 females). The median age for participants was 60 years. Most participants described the MBSR taster session as a positive experience. The main challenge reported was trying to maintain focus and concentration throughout the MBSR session. Some participants expressed reservations about the duration of standard mindfulness course sessions, suggesting a preference for shorter sessions. The potential for achieving better control over negative thoughts and emotions was viewed as a potential facilitator for future MBSR participation. Participants suggested having an orientation session prior to starting an 8-week course as a means of developing familiarity with the MBSR instructor and other participants. Conclusion: It was feasible to recruit 21 stroke survivors and 7 caregivers for MBSR taster sessions in the community. A shorter MBSR session and an orientation session prior to the full course are suggestions for potential MBSR modifications for stroke survivors, which needs further research and evaluation

Using normalisation process theory to understand barriers and facilitators to implementing mindfulness-based stress reduction for people with multiple sclerosis

Objectives: To study barriers and facilitators to implementation of mindfulness-based stress reduction for people with multiple sclerosis. Methods: Qualitative interviews were used to explore barriers and facilitators to implementation of mindfulness-based stress reduction, including 33 people with multiple sclerosis, 6 multiple sclerosis clinicians and 2 course instructors. Normalisation process theory provided the underpinning conceptual framework. Data were analysed deductively using normalisation process theory constructs (coherence, cognitive participation, collective action and reflexive monitoring). Results: Key barriers included mismatched stakeholder expectations, lack of knowledge about mindfulness-based stress reduction, high levels of comorbidity and disability and skepticism about embedding mindfulness-based stress reduction in routine multiple sclerosis care. Facilitators to implementation included introducing a pre-course orientation session; adaptations to mindfulness-based stress reduction to accommodate comorbidity and disability and participants suggested smaller, shorter classes, shortened practices, exclusion of mindful-walking and more time with peers. Post-mindfulness-based stress reduction booster sessions may be required, and objective and subjective reports of benefit would increase clinician confidence in mindfulness-based stress reduction. Discussion: Multiple sclerosis patients and clinicians know little about mindfulness-based stress reduction. Mismatched expectations are a barrier to participation, as is rigid application of mindfulness-based stress reduction in the context of disability. Course adaptations in response to patient needs would facilitate uptake and utilisation. Rendering access to mindfulness-based stress reduction rapid and flexible could facilitate implementation. Embedded outcome assessment is desirable

Mindfulness-based interventions for mental well-being among people with multiple sclerosis: a systematic review and meta-analysis of randomised controlled trials

Objective: Impairment of mental well-being (anxiety, depression, stress) is common among people with multiple sclerosis (PwMS). Treatment options are limited, particularly for anxiety. The aim of this study was to update our previous systematic review (2014) and evaluate via meta-analysis the efficacy of mindfulness-based interventions (MBIs) for improving mental well-being in PwMS. Methods: Systematic searches for eligible randomised controlled trials (RCTs) were carried out in seven major databases (November 2017, July 2018), using medical subject headings and key words. Studies were screened, data extracted, quality appraised and analysed by two independent reviewers, using predefined criteria. Study quality was assessed using the Cochrane Collaboration risk of bias tool. Mental well-being was the primary outcome. Random effects model meta-analysis was performed, with effect size reported as standardised mean difference (SMD). Results: Twelve RCTs including 744 PwMS were eligible for inclusion in the systematic review, eight had data extractable for meta-analysis; n=635. Ethnicity, socioeconomic status, comorbidity and disability were inconsistently reported. MBIs varied from manualised to tailored versions, lasting 6–9 weeks, delivered individually and via groups, both in person and online. Overall SMD for mental well-being (eight studies) was 0.40 (0.28–0.53), p<0.01, I2=28%; against active comparators only (three studies) SMD was 0.17 (0.01–0.32), p<0.05, I2 =0%. Only three adverse events were reported. Conclusions: MBIs are effective at improving mental well-being in PwMS. More research is needed regarding optimal delivery method, cost-effectiveness and comparative-effectiveness

Processing of seismic data from an automatic digital recorder

Data from a three-component, long-period seismometer system is recorded in digital form on magnetic tape by a device which has been described by Miller. Preliminary editing and processing is performed to select events of interest from the 24-hour tapes and place them on a library tape that is compatible with a computer. Emphasis is placed on location, correction, and flagging of errors that occur during the recording and editing process. Processing routines developed include: correction for seismometer response, orbital motion functions, energy computation, band pass filtering for mode separation, etc. The dynamic range of the system is 86 db and the response is adequate over the range .02 to 2.0 cps. For the purpose of detailed analysis, digital records from this system are superior to paper records from any of the existing seismographs in use at this laboratory. The main disadvantage of data in this form is the difficulty of inspecting signals by eye in order to make preliminary interpretations

Editorial

In the past years, digital signal processing (DSP) algorithms and architectures for baseband communication systems have fuelled the delivery of applications such as 3G mobile communications and wireless LAN to mass markets. This was made possible by a tremendous growth in the performance of computational devices such as digital signal processors and FPGAs, as well as an increase in sampling rates of conversion devices to potentially several 100 MHz. While the development of both computational devices and ADCs/DACs continues, thus permitting DSP to be applied at IF sampling rates and possibly beyond, the opportunities for further enhancing radio devices by DSP algorithms and architectures arise. Against this background of development, an IEE/EURASIP conference on “DSP-Enabled Radio” was held at the Institute for System Level Integration (ISLI) in Livingston, Scotland, in September 2003. This very lively one-and-ahalf- day event brought together 120 researchers from both industry and academia with a strong international participation. It was the spirit of this DSP-Enabled Radio conference and the contributions therein that brought to life the idea to this special issue. This issue contains both contributions from the event and responses to an open call for papers

Dynamic spectrum access : secondary user coexistence in the FM band

The explosion of wireless everything in recent years has placed a strain on the radio spectrum, and has led to the so-called ‘spectrum crunch’, where the spectrum is described as being nearly at capacity [1]. It is widely accepted that in reality this is not the case, as great numbers of ‘allocated’ bands are underutilized or not in use at all. In other words, the radio spectrum is not used as efficiently as it could be. Commonly, bands (containing many channels) are classified by spectrum regulators for a particular type of use, such as those for FM Radio, Digital TV and cellular services. If there are not enough Primary Users (PUs) to use all of the channels in these bands, they lie empty. Using new spectrum access techniques, these channels can be targeted for 5G and IoT applications. This work focuses on targeting the FM Radio band (88-108 MHz). Signals broadcast at these frequencies have excellent propagation characteristics, and are able to diffract around objects such as hills and human-made structures, and penetrate through buildings well. Recent studies [2] have shown that a significant portion of the 100 individual 200 kHz-wide FM Radio channels are unused at any given location

Training based channel estimation algorithms for dual hop MIMO OFDM relay systems

In this paper we consider minimum mean square error (MMSE) training based channel estimation for two-hop multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) relaying systems. The channel estimation process is divided into two main phases. The relay-destination channel is estimated in the first phase and can be obtained using well known point-to-point MIMO OFDM estimation methods. In the second phase, the source-relay channel is estimated at the destination with the use of a known training sequence that is transmitted from the source and forwarded to the destination by a non-regenerative relay. To obtain an estimate of the source-relay channel, the source training sequence, relay precoder, and destination processor, require to be optimised. To solve this problem we derive an iterative algorithm that involves sequentially solving a number of convex optimisation problems to update the source, relay, and destination design variables. Since the iterative algorithm may be too computationally expensive for practical implementation we then derive simplified solutions that have reduced computational complexity. Simulation results demonstrate the effectiveness of the proposed algorithms