Training-Symbol Embedded, High-Rate Complex Orthogonal Designs for Relay Networks

Distributed Space-Time Block Codes (DSTBCs) from Complex Orthogonal Designs (CODs) (both square and non-square CODs other than the Alamouti design) are known to lose their single-symbol ML decodable (SSD) property when used in two-hop wireless relay networks using the amplify and forward protocol. For such a network, a new class of high rate, training-symbol embedded (TSE) SSD DSTBCs are proposed from TSE-CODs. The constructed codes include the training symbols within the structure of the code which is shown to be the key point to obtain high rate along with the SSD property. TSE-CODs are shown to offer full-diversity for arbitrary complex constellations. Non-square TSE-CODs are shown to provide better rates (in symbols per channel use) compared to the known SSD DSTBCs for relay networks when the number of relays is less than 10. Importantly, the proposed DSTBCs do not contain zeros in their codewords and as a result, antennas of the relay nodes do not undergo a sequence of switch on and off transitions within every codeword use. Hence, the proposed DSTBCs eliminate the antenna switching problem.

Training-Embedded, Single-Symbol ML-Decodable, Distributed STBCs for Relay Networks

Recently, a special class of complex designs called Training-Embedded Complex Orthogonal Designs (TE-CODs) has been introduced to construct single-symbol Maximum Likelihood decodable (SSD) distributed space-time block codes (DSTBCs) for two-hop wireless relay networks using the amplify and forward protocol. However, to implement DSTBCs from square TE-CODs, the overhead due to the transmission of training symbols becomes prohibitively large as the number of relays increase. In this paper, we propose TE-Coordinate Interleaved Orthogonal Designs (TE-CIODs) to construct SSD DSTBCs. Exploiting the block diagonal structure of TE-CIODs, we show that the overhead due to the transmission of training symbols to implement DSTBCs from TE-CIODs is smaller than that for TE-CODs. We also show that DSTBCs from TE-CIODs offer higher rate than those from TE-CODs for identical number of relays while maintaining the SSD and full-diversity properties.

Antenna Selection Training in MIMO-OFDM/OFDMA Cellular Systems

Antenna selection allows multiple-antenna systems to achieve most of their promised diversity gain, while keeping the number of RF chains and, thus, cost/complexity low. In this paper we investigate antenna selection for fourth-generation OFDMA- based cellular communications systems, in particular, 3GPP LTE (long-term evolution) systems. We propose a training method for antenna selection that is especially suitable for OFDMA. By means of simulation, we evaluate the SNR-gain that can be achieved with our design. We find that the performance depends on the bandwidth assigned to each user, the scheduling method (round-robin or frequency-domain scheduling), and the Doppler spread. Furthermore, the signal-to-noise ratio of the training sequence plays a critical role. Typical SNR gains are around 2 dB, with larger values obtainable in certain circumstances.

Training-Symbol Embedded, High-Rate, Single-Symbol ML-Decodable, Distributed STBCs for Relay Networks

Distributed space-time block codes (DSTBCs) from complex orthogonal designs (CODs) (both square and nonsquare), coordinate interleaved orthogonal designs (CIODs), and Clifford unitary weight designs (CUWDs) are known to lose their single-symbol ML decodable (SSD) property when used in two-hop wireless relay networks using amplify and forward protocol. For such networks, in this paper, three new classes of high rate, training-symbol embedded (TSE) SSD DSTBCs are constructed: TSE-CODs, TSE-CIODs, and TSE-CUWDs. The proposed codes include the training symbols inside the structure of the code which is shown to be the key point to obtain the SSD property along with the channel estimation capability. TSE-CODs are shown to offer full-diversity for arbitrary complex constellations and the constellations for which TSE-CIODs and TSE-CUWDs offer full-diversity are characterized. It is shown that DSTBCs from nonsquare TSE-CODs provide better rates (in symbols per channel use) when compared to the known SSD DSTBCs for relay networks. Important from the practical point of view, the proposed DSTBCs do not contain any zeros in their codewords and as a result, antennas of the relay nodes do not undergo a sequence of switch on/off transitions within every codeword, and, thus, avoid the antenna switching problem.

Modulation Diversity in Fading Channels with a Quantized Receiver

In this paper, we address the design of codes which achieve modulation diversity in block fading single-input single-output (SISO) channels with signal quantization at the receiver. With an unquantized receiver, coding based on algebraic rotations is known to achieve maximum modulation coding diversity. On the other hand, with a quantized receiver, algebraic rotations may not guarantee gains in diversity. Through analysis, we propose specific rotations which result in the codewords having equidistant component-wise projections. We show that the proposed coding scheme achieves maximum modulation diversity with a low-complexity minimum distance decoder and perfect channel knowledge. Relaxing the perfect channel knowledge assumption we propose a novel channel training/estimation technique to estimate the channel. We show that our coding/training/estimation scheme and minimum distance decoding achieves an error probability performance similar to that achieved with perfect channel knowledge.

Diversity in ranking via resistive graph centers

Users can rarely reveal their information need in full detail to a search engine within 1--2 words, so search engines need to "hedge their bets" and present diverse results within the precious 10 response slots. Diversity in ranking is of much recent interest. Most existing solutions estimate the marginal utility of an item given a set of items already in the response, and then use variants of greedy set cover. Others design graphs with the items as nodes and choose diverse items based on visit rates (PageRank). Here we introduce a radically new and natural formulation of diversity as finding centers in resistive graphs. Unlike in PageRank, we do not specify the edge resistances (equivalently, conductances) and ask for node visit rates. Instead, we look for a sparse set of center nodes so that the effective conductance from the center to the rest of the graph has maximum entropy. We give a cogent semantic justification for turning PageRank thus on its head. In marked deviation from prior work, our edge resistances are learnt from training data. Inference and learning are NP-hard, but we give practical solutions. In extensive experiments with subtopic retrieval, social network search, and document summarization, our approach convincingly surpasses recently-published diversity algorithms like subtopic cover, max-marginal relevance (MMR), Grasshopper, DivRank, and SVMdiv.

Training for Antenna Selection in Time-Varying Channels: Optimal Selection, Energy Allocation, and Energy Efficiency Evaluation

Single receive antenna selection (AS) is a popular method for obtaining diversity benefits without the additional costs of multiple radio receiver chains. Since only one antenna receives at any time, the transmitter sends a pilot multiple times to enable the receiver to estimate the channel gains of its N antennas to the transmitter and select an antenna. In time-varying channels, the channel estimates of different antennas are outdated to different extents. We analyze the symbol error probability (SEP) in time-varying channels of the N-pilot and (N+1)-pilot AS training schemes. In the former, the transmitter sends one pilot for each receive antenna. In the latter, the transmitter sends one additional pilot that helps sample the channel fading process of the selected antenna twice. We present several new results about the SEP, optimal energy allocation across pilots and data, and optimal selection rule in time-varying channels for the two schemes. We show that due to the unique nature of AS, the (N+1)-pilot scheme, despite its longer training duration, is much more energy-efficient than the conventional N-pilot scheme. An extension to a practical scenario where all data symbols of a packet are received by the same antenna is also investigated.

Diversity of selective and non-selective fishing gear and their impact on inland fisheries in Bangladesh

The paper describes the wide range of traditional fishing gear used by subsistence and professional fishers in the inland waters in Bangladesh as well as their impact on the fisheries and the environment. The negative impacts indicate the need for regulation of specific types of fishing gear at particular times of the year. An awareness/training program should be extended to the fishermen to create awareness of the long-term effects of their fishing practices and to impart knowledge of fishing laws.

Diversity and Inclusion at UMD Libraries Survey Results

The survey was made available online to library faculty, staff, and student workers. Participation in the survey was completely voluntary, and each individual question was entirely optional. In accordance with UMD policy, responses were treated as confidential. Fewer than five responses in a particular category were considered identifiable by the U.S. Department of Education and were not included in this report. Those who participated in the survey represent a significant portion of the Libraries’ community.

Diversity in the fitness industry : a cross-case comparison /

This cross-case study explored the extent to which two fitness facilities were accommodating diversity with respect to age, ethnicity, gender, social class, sex-role socialization, and persons with a disability among both members and staflf. The sites were purposely chosen in a large city and a smaller city in order to provide as representative an example as possible of health clubs within a small sample population. The interview participants were selected by a combination of stratified, typical case, and snowball sampling strategies. . , .. , The intent of the exploration was a two-fold examination of diversity issues within both the membership and the staff of the organization. Data were collected and analysis was done using a triangulation method involving personal interviews, observations, and facility documentation. The results ofthe study showed that the members and staff at each facility were rather homogeneous in ethnicity, age, social class, physical ability, and physical appearance. From a membership standpoint, the environment of the sites presented the impression of being affordable only to the middle- and upper-middle classes, unwelcoming to the older, less fit, or overweight participant, economically exclusive for youth, and nonaccommodating for people with a disability. With respect to staff, the findings indicated that the fitness facilities purported to be team-oriented in theory, but were hierarchical in practice, with the major decision making being made by the male executives. The paper concludes with the recommendation that students must be given a practical toolkit for dealing with these issues in their postsecondary courses.

Measuring bee diversity in different European habitats and biogeographical regions

Bee pollinators are currently recorded with many different sampling methods. However, the relative performances of these methods have not been systematically evaluated and compared. In response to the strong need to record ongoing shifts in pollinator diversity and abundance, global and regional pollinator initiatives must adopt standardized sampling protocols when developing large-scale and long-term monitoring schemes. We systematically evaluated the performance of six sampling methods (observation plots, pan traps, standardized and variable transect walks, trap nests with reed internodes or paper tubes) that are commonly used across a wide range of geographical regions in Europe and in two habitat types (agricultural and seminatural). We focused on bees since they represent the most important pollinator group worldwide. Several characteristics of the methods were considered in order to evaluate their performance in assessing bee diversity: sample coverage, observed species richness, species richness estimators, collector biases (identified by subunit-based rarefaction curves), species composition of the samples, and the indication of overall bee species richness (estimated from combined total samples). The most efficient method in all geographical regions, in both the agricultural and seminatural habitats, was the pan trap method. It had the highest sample coverage, collected the highest number of species, showed negligible collector bias, detected similar species as the transect methods, and was the best indicator of overall bee species richness. The transect methods were also relatively efficient, but they had a significant collector bias. The observation plots showed poor performance. As trap nests are restricted to cavity-nesting bee species, they had a naturally low sample coverage. However, both trap nest types detected additional species that were not recorded by any of the other methods. For large-scale and long-term monitoring schemes with surveyors with different experience levels, we recommend pan traps as the most efficient, unbiased, and cost-effective method for sampling bee diversity. Trap nests with reed internodes could be used as a complementary sampling method to maximize the numbers of collected species. Transect walks are the principal method for detailed studies focusing on plant-pollinator associations. Moreover, they can be used in monitoring schemes after training the surveyors to standardize their collection skills.

Preparing early childhood professionals to work with parents: the challenges of diversity and dissensus

This article examines how early childhood staff in diverse circumstances negotiate relationships with parents. It draws on interviews with staff in two rural and three urban communities in Australia, who were asked about their parent communication practices, their experiences of these practices, and their preferences within these practices. Their responses were analysed in the light of international research showing the importance of creating strong interpretive communities between staff and parents but consistent staff anxiety about their relationships with parents. The paper explores the extent to which staff's different approaches to communicating with parents can create sustainable interpretive communities between them, and it highlights some implications for staff training and development around parent involvement.

Nurses' perceived training needs in child protection issues

Purpose – The purpose of this research is to explore nurses' perceptions of their current skills and knowledge and training needs to identify cases of child abuse and their understanding of their roles and responsibilities in relation to child abuse. Nurses, including health visitors and midwives, have been recognised as having a key role in the protection and care of children, especially in identifying and referring possible cases of child abuse and neglect.

Design/methodology/approach – A structured questionnaire concerning knowledge and training needs in child protection was sent to all nurses employed in a Scottish NHS Primary Care Trust (approximately 1,900), of whom one-third (667) responded. These survey results were complemented by semi-structured interviews with 99 members of the nursing workforce.

Findings – Almost all training in child protection had been confined to health visitors, resulting in the Trust giving an implicit message that child protection is not a role in which other nurses need have any involvement. In general, those nurses who both worked with children and had involvement in child protection issues, considered themselves to be most in need of knowledge around child protection work, to have the greatest level of knowledge and to consider further training a priority.

Research limitations/implications – Nurses who had an interest or involvement in child protection work were more likely to participate in the research, which may have biased the results.

Practical implications – Training strategies need to address the diversity of nurses' involvements in child protection work through the development of training programmes which are appropriate for different workplaces and different occupational groupings. Nurses in some settings will need to be first convinced they have the potential to play an important role in protecting children from abuse and neglect.

Originality/value – Many NHS Trusts have in recent years introduced mandatory training in child protection for all staff in contact with children. However, previously published studies have considered training issues only in respect of nurses identified as working directly with children, whereas this study explores child protection issues for all nurses employed in a primary care NHS Trust.

Technology and teachers in rural schools : diversity and similarity

This paper reports on a project situated in regional areas of Victoria in which 16 primary and secondary teachers participated in an intensive professional development program designed to assist them in embedding Information Communications Technology (ICT) into their classroom practice. The project provides some insight into the availability and use of current technological resources in the rural schools and examines the impact of an intensive professional development program on the implementation of ICT into the curriculum.

The results identified a large diversity of circumstances experienced by the schools in the project, not only in terms of ICT availability and use, and teacher experience, but also in more general issues of cultures of curriculum planning and integration, size, communication, and pedagogical presumptions. The successful integration of ICT into their pedagogical practice was influenced by a complex of factors including the availability of ICT resources, the teachers’ ICT skill level, the teachers’ ability and opportunity to integrate ICT in classroom, the level of support provided, both technical and pedagogical, and the curriculum requirements.

The results of the project have been positive with evidence of increased networking among the teachers, changes in teaching practice and increased teacher proficiency and awareness of ICT resources. The project has highlighted common difficulties that teachers experienced including frustrations with the unreliability of technology and a lack of time for necessary training and preparation. In response to the constraints, teachers have been resourceful and inventive in developing pedagogical strategies to aid the integration of ICT into their classroom practice.