Andrew Grundy

Efficient and adaptive congestion control for heterogeneous delay-tolerant networks

Detecting and dealing with congestion in delay-tolerant networks (DTNs) is an important and challenging problem. Current DTN forwarding algorithms typically direct traffic towards more central nodes in order to maximise delivery ratios and minimise delays, but as traffic demands increase these nodes may become saturated and unusable. We propose CafRep, an adaptive congestion aware protocol that detects and reacts to congested nodes and congested parts of the network by using implicit hybrid contact and resources congestion heuristics. CafRep exploits localised relative utility based approach to offload the traffic from more to less congested parts of the network, and to replicate at adaptively lower rate in different parts of the network with non-uniform congestion levels. We extensively evaluate our work against benchmark and competitive protocols across a range of metrics over three real connectivity and GPS traces such as Sassy 44], San Francisco Cabs 45] and Infocom 2006 33]. We show that CafRep performs well, independent of network connectivity and mobility patterns, and consistently outperforms the state-of-the-art DTN forwarding algorithms in the face of increasing rates of congestion. CafRep maintains higher availability and success ratios while keeping low delays, packet loss rates and delivery cost. We test CafRep in the presence of two application scenarios, with fixed rate traffic and with real world Facebook application traffic demands, showing that regardless of the type of traffic CafRep aims to deliver, it reduces congestion and improves forwarding performance.

Bringing meaning to user involvement in mental health care planning: a qualitative exploration of service user perspectives

BACKGROUND Service users wish to be involved in care planning but typically feel marginalized in this process. Qualitative explorations of the barriers and enablers of user involvement in mental health care planning are limited. QUESTION How is user involvement in care planning conceptualized by service users and how can meaningful involvement be instilled in the care planning process? METHODS In 2013, we conducted five focus groups (n = 27) and 23 individual interviews with current or recent adult users of secondary care mental health services (n = 27) in England. Eight users participated in both. Data were analysed using Framework Analysis. Results Ten themes emerged from the data: these themes encompassed procedural elements (connection; contribution; currency; care consolidation; and consequence), service user characteristics (capacity and confidence) and professional enablers (consultation; choice; and clarity of expression). Procedural elements were discussed most frequently in service user discourse. DISCUSSION The process of care planning, centred on the user-clinician relationship, is key to user involvement. IMPLICATIONS FOR PRACTICE Users describe a common model of meaningful involvement in care planning. Their requests, summarized through a 10C framework of care planning involvement, provide clear direction for improving service users satisfaction with care planning and enhancing the culture of services.

Congestion aware forwarding in delay tolerant and social opportunistic networks

We propose an approach for opportunistic forwarding that supports optimization of multipoint high volume data flow transfer while maintaining high buffer availability and low delays. This paper explores a number of social, buffer and delay heuristics to offload the traffic from congested parts of the network and spread it over less congested parts of the network in order to keep low delays, high success ratios and high availability of nodes. We conduct an extensive set of experiments for assessing the performance of four newly proposed heuristics and compare them with Epidemic, Prophet, Spay and Wait and Spay and Focus protocols over real connectivity driven traces (RollerNet) and with a realistic publish subscribe filecasting application. We look into success ratio of answered queries, download times (delays) and availability of buffer across eight protocols for varying congestion levels in the face of increasing number of publishers and topic popularity. We show that all of our combined metrics perform better than Epidemic protocol, Prophet, Spray and Wait, Spray and Focus and our previous prototype across all the assessed criteria.

Promoting congestion control in opportunistic networks

This paper is concerned with congestion aware forwarding algorithms within opportunistic networks. We remove the reoccurring assumption of unlimited storage, and make it evident that congestion is a prominent problem that needs to be addressed. We propose a distributed congestion control algorithm that adaptively chooses the next hop based on contact history and statistics, as well as storage statistics. We aim to distribute the load away from the storage hotspots in order to spread the traffic around. We perform an extensive set of trace driven simulations for “several-to-many” communication patterns in opportunistic networks. We show that congestion control is an essential component in the transfer of data in opportunistic networks, and can be achieved in a fully open loop manner and by only local dissemination of statistics of nodes availability and connectivity. Our results with real connectivity traces show that by using novel availability heuristic we achieve higher levels of sent and delivered packets and outperform current opportunistic forwarding protocols, such as SimBetTS and FairRoute.

Framework for utility driven congestion control in delay tolerant opportunistic networks

Detecting and dealing with congestion in delay tolerant opportunistic networks is an important and challenging problem. In this paper we describe CAFREP, a unified congestion control framework for routing in such networks that adapts both data sending rates and data forwarding policies through a novel reactive fully distributed approach. CAFREP enables congestion control by detecting and reacting to congested nodes and congested parts of the network by using implicit hybrid contact and resources congestion heuristic. CAFREP exploits localized relative utility based approach to offload the traffic from more to less congested parts of the network, and replicate at adaptively lower rate in parts of the network with higher congestion. We extensively evaluate CAFREP against a number of state of the art adaptive and non-adaptive DTN routing protocols across a number of different metrics over three real trace driven experiments with different mobility and connectivity patterns such as Infocom 2006, Rollernet and Dieselnet CRAWDAD data sets. We show that CAFREP performs well in three different connectivity datasets and continuously outperforms four other protocols in terms of maintaining higher node availability and success ratio while keeping lower delays, lower packet loss rates and lower number of forwarded packets for increasing congestion levels.

Congestion aware data dissemination in social opportunistic networks

Recent developments in social-based opportunistic forwarding [1], [2], [10] have identified that load is unfairly distributed towards nodes which are better connected. Unfair load distribution and high unrestricted volumes of traffic produce congestion. Congestion in opportunistic and delay tolerant networks takes the form of persistent storage exhaustion [1][4]. Several solutions exist including slowing sources, using alternative routes, discarding traffic, or migrating messages to alternative storage locations. We focus on congestion aware forwarding algorithms that adaptively choose the next hop based on contact history, predictive storage and delay analysis in order to distribute the load away from the storage hotspots and spread the traffic around. We describe new forwarding heuristics that uses nearby nodes with available storage and low delays to store data that would otherwise be lost during opportunistic bulk data transfers. More specifically we describe the two metrics Receptiveness and Retentiveness, each is a measurement of how utilised a node is, regarding node delays and buffer capacity respectively. Our heuristics factors in a cost metric associated with storage and delays so that the traffic is spread away from ego-network-centric paths and only paths with more storage and lower delays are chosen at times of congestion. Our heuristics makes use of the diversity of forwarding paths in human contact networks [7] by forwarding packets along multiple paths similarly to the resource pooling principal [6]. For our evaluation, we perform an extensive set of trace driven simulations for an opportunistic peer to peer file casting application. We build a realistic interest-driven P2P content dissemination overlay on the top of our congestion aware forwarding protocol. Our results show that our availability heuristics dramatically increases robustness of content distribution in terms of shorter download times and higher ratio of queries being successfully solved in the face of increasing congestion levels while still maintaining high availability among nodes when compared to SimBetTs[11] and Fairroute[4]. We induce congestion levels by increasing the topics popularity (number of randomly chosen subscribers) and the number of randomly chosen file publishers from 3% to almost 100%.

Decongesting opportunistic social-based forwarding

Social network based forwarding algorithms for opportunistic networks, such as Pocket Switched Networks, are primarily concerned with throughput and efficiency. In this paper we seek to improve our understanding of how forwarding based on a heuristic that favours connectivity causes unfair load distribution, which in turn leads to congestion. We propose a number of metrics, that help balance the load distribution and actively prevent congestion. We optimise and filter existing metrics such as Centrality and Similarity, and introduce Availability and Performance feedback mechanisms. We state a preliminary Utility formula that combines our observations allowing us to select a suitable next hop. We present initial modelling results showing that our refinement techniques improve the balance of load distribution, reducing the stress on individual nodes.

A cluster randomised controlled trial and process evaluation of a training programme for mental health professionals to enhance user involvement in care planning in service users with severe mental health issues (EQUIP): study protocol for a randomised controlled trial

BackgroundInvolving service users in planning their care is at the centre of policy initiatives to improve mental health care quality in England. Whilst users value care planning and want to be more involved in their own care, there is substantial empirical evidence that the majority of users are not fully involved in the care planning process. Our aim is to evaluate the effectiveness and cost-effectiveness of training for mental health professionals in improving user involvement with the care planning processes.Methods/DesignThis is a cluster randomised controlled trial of community mental health teams in NHS Trusts in England allocated either to a training intervention to improve user and carer involvement in care planning or control (no training and care planning as usual).We will evaluate the effectiveness of the training intervention using a mixed design, including a ‘cluster cohort’ sample, a ‘cluster cross-sectional’ sample and process evaluation. Service users will be recruited from the caseloads of care co-ordinators.The primary outcome will be change in self-reported involvement in care planning as measured by the validated Health Care Climate Questionnaire. Secondary outcomes include involvement in care planning, satisfaction with services, medication side-effects, recovery and hope, mental health symptoms, alliance/engagement, well-being and quality of life. Cost- effectiveness will also be measured. A process evaluation informed by implementation theory will be undertaken to assess the extent to which the training was implemented and to gauge sustainability beyond the time-frame of the trial.DiscussionIt is hoped that the trial will generate data to inform mental health care policy and practice on care planning.Trial Registration NumberISRCTN16488358 (14 May 2014)

EQUIP training the trainers: an evaluation of a training programme for service users and carers involved in training mental health professionals in user‐involved care planning

Accessible summary What is known on the subject?UK NHS policy highlights the importance of user and carer involvement in health professional training.We know little about service user and carer motivations and experiences of accessing training courses for delivering training to health professionals and how well such courses prepare them for delivering training to healthcare professionals.‘Involvement’ in training has often been tokenistic and too narrowly focused on preregistration courses.There is limited data on how best to prepare and support potential service user and carer trainers. &NA; What does this paper add to existing knowledge?This study adds to the international literature by highlighting service user and carer motivations for accessing a training course for delivering training to health professionals.Service users and carers wanted to gain new skills and confidence in presentation/facilitation as well as to make a difference to healthcare practice. We also learned that service users desired different levels of involvement in training facilitation – some wanted to take a more active role than others.A one‐size‐fits‐all approach is not always appropriate. Encountering resistance from staff in training was a previously unidentified challenge to service user and carers’ experience of delivering training in practice and is a key challenge for trainers to address in future.Professional training involvement can be enhanced via specialist training such as the EQUIP training the trainers programme evaluated here. &NA; What are the implications for practice?When training service users and carers to deliver training to mental health professionals, it is important that service users are equipped to deal with resistance from staff.It is important that service user and carer roles are negotiated and agreed prior to delivering training to healthcare professionals to accommodate individual preferences and allay anxieties.Training for service users and carers must be offered alongside ongoing support and supervision.Mental health nurses (and other health professionals) will be better able to involve service users and carers in care planning.Service users and carers may feel more involved in care planning in future. Introduction: Limited evidence exists on service user and carer perceptions of undertaking a training course for delivering care planning training to qualified mental health professionals. We know little about trainee motivations for engaging with such train the trainers courses, experiences of attending courses and trainees’ subsequent experiences of codelivering training to health professionals, hence the current study. Aim: To obtain participants’ views on the suitability and acceptability of a training programme that aimed to prepare service users and carers to codeliver training to health professionals. Method: Semi‐structured interviews with nine service users and carers attending the training programme. Transcripts were analysed using inductive thematic analysis. Results: Participants’ reasons for attending training included skill development and making a difference to mental health practice. Course content was generally rated highly but may benefit from review and/or extension to allow the range of topics and resulting professional training programme to be covered in more depth. Trainees who delivered the care planning training reported a mix of expectations, support experiences, preparedness and personal impacts. Implications for Practice: Mental health nurses are increasingly coproducing and delivering training with service users and carers. This study identifies possibilities and pitfalls in this endeavour, highlighting areas where user and carer involvement and support structures might be improved in order to fully realize the potential for involvement in training.

Understanding experiences of and preferences for service user and carer involvement in physical health care discussions within mental health care planning

BackgroundPeople with severe mental illness suffer more physical comorbidity than the general population, which can require a tailored approach to physical health care discussions within mental health care planning. Although evidence pertaining to service user and carer involvement in mental health care planning is accumulating, current understanding of how physical health is prioritised within this framework is limited. Understanding stakeholder experiences of physical health discussions within mental health care planning, and the key domains that underpin this phenomena is essential to improve quality of care. Our study aimed to explore service user, carer and professional experiences of and preferences for service user and carer involvement in physical health discussions within mental health care planning, and develop a conceptual framework of effective user-led involvement in this aspect of service provision.MethodsSix focus groups and four telephone interviews were carried out with twelve service users, nine carers, three service users with a dual service user and carer role, and ten mental health professionals recruited from one mental health Trust in the United Kingdom. Data was analysed utilising a thematic approach, analysed separately for each stakeholder group, and combined to aid comparisons.ResultsNo service users or carers recalled being explicitly involved in physical health discussions within mental health care planning. Six prerequisites for effective service user and carer involvement in physical care planning were identified. Three themes confirmed general mental health care planning requirements: tailoring a collaborative working relationship, maintaining a trusting relationship with a professional, and having access to and being able to edit a living document. Three themes were novel to feeling involved in physical health care planning discussions: valuing physical health equally with mental health; experiencing coordination of care between physical-mental health professionals, and having a physical health discussion that is personalised.ConclusionsHigh quality physical health care discussions within the care planning process demands action at multiple levels. A conceptual framework is presented which provides an evidence-based foundation for service level improvement. Further work is necessary to develop a new patient reported outcome measure to enable meaningful quantification of health care quality and patient experience.