Layered Steered Space-Time Codes and their capacity

A capacity analysis of a multifunctional multiple-input multiple-output system that combines the benefits of vertical Bell Labs space-time scheme, space-time block codes and beamforming is presented

Coherent and Differential Downlink Space-Time Steering Aided Generalised Multicarrier DS-CDMA

This paper presents a generalised MultiCarrier Direct Sequence Code Division Multiple Access (MC DS-CDMA) system invoking smart antennas for improving the achievable performance in the downlink. In this contribution, the MC DSCDMA transmitter employs an Antenna Array (AA) and Steered Space-Time Spreading (SSTS). Furthermore, the proposed system employs both Time and Frequency (TF) domain spreading for extending the capacity of the system, which is combined with a user-grouping technique for reducing the effects of Multi-User Interference (MUI). Moreover, to eliminate the high complexity Multiple Input Multiple Output (MIMO) channel estimation required for coherent detection, we also propose a Differential SSTS (DSSTS) scheme. More explicitly, for coherent SSTS detection MVNr number of channel estimates have to be generated, where M is the number of transmit AAs, V is the number of subcarriers and Nr is the number of receive antennas. This is a challenging task, which renders the low-complexity DSSTS scheme attractive. Index Terms—MIMO, MC DS-CDMA, beamforming, spacetime spreading, differential space-time spreading

Downlink Steered Space-Time Spreading Assisted Generalised Multicarrier DS-CDMA Using Sphere-Packing-Aided Multilevel Coding

This paper presents a novel generalised Multi-Carrier Direct Sequence Code Division Multiple Access (MC DS-CDMA) system invoking smart antennas for improving the achievable performance in the downlink, as well as employing multi-dimensional Sphere Packing (SP) modulation for increasing the achievable diversity product. In this contribution, the MC DS-CDMA transmitter considered employs multiple Antenna Arrays (AA) and each of the AAs consists of several antenna elements. Furthermore, the proposed system employs both time- and frequency- (TF) domain spreading for extending the achievable capacity, when combined with a novel user-grouping technique for reducing the effects of Multiuser Interference (MUI). Moreover, in order to further enhance the system’s performance, we invoke a MultiLevel Coding (MLC) scheme, whose component codes are determined using the so-called equivalent capacity based constituent-code rate-calculation procedure invoking a 4-dimensional bit-to-SP-symbol mapping scheme. Our results demonstrate an approximately 3.8 dB Eb/N0 gain over an identical throughput scheme dispensing with SP modulation at a BER of 10?5

Iteratively Decoded Irregular Variable Length Coding and Sphere-Packing Modulation-Aided Differential Space-Time Spreading

In this paper we consider serially concatenated and iteratively decoded Irregular Variable Length Coding (IrVLC) combined with precoded Differential Space-Time Spreading (DSTS) aided multidimensional Sphere Packing (SP) modulation designed for near-capacity joint source and channel coding. The IrVLC scheme comprises a number of component Variable Length Coding (VLC) codebooks having different coding rates for the sake of encoding particular fractions of the input source symbol stream. The relative length of these source-stream fractions can be chosen with the aid of EXtrinsic Information Transfer (EXIT) charts in order to shape the EXIT curve of the IrVLC codec, so that an open EXIT chart tunnel may be created even at low Eb/N0 values that are close to the capacity bound of the channel. These schemes are shown to be capable of operating within 0.9 dB of the DSTS-SP channel’s capacity bound using an average interleaver length of 113, 100 bits and an effective bandwidth efficiency of 1 bit/s/Hz, assuming ideal Nyquist filtering. By contrast, the equivalent-rate regular VLC-based benchmarker scheme was found to be capable of operating at 1.4 dB from the capacity bound, which is about 1.56 times the corresponding discrepancy of the proposed IrVLC-aided scheme

Clinical consequences of polypharmacy in elderly.

INTRODUCTION: Polypharmacy, defined as the use of multiple drugs or more than are medically necessary, is a growing concern for older adults. MEDLINE and EMBASE databases were searched from January 1, 1986 to June 30, 2013) to identify relevant articles in people aged \u3e 65 years. AREAS COVERED: We present information about: i) prevalence of polypharmacy and unnecessary medication use; ii) negative consequences of polypharmacy; and iii) interventions to improve polypharmacy. EXPERT OPINION: International research shows that polypharmacy is common in older adults with the highest number of drugs taken by those residing in nursing homes. Nearly 50% of older adults take one or more medications that are not medically necessary. Research has clearly established a strong relationship between polypharmacy and negative clinical consequences. Moreover, well-designed interprofessional (often including clinical pharmacist) intervention studies that focus on enrolling high-risk older patients with polypharmacy have shown that they can be effective in reducing aspects of unnecessary prescribing with mixed results on distal health outcomes

The Change of the Vessel Markings by Ligation of the Branch of the Pulmonary Artery

In relation with the collapse therapy of the lung, I observed the change of vessel markings of the lobe when the secondary atrophy of the lung occurs by ligation of pulmonary artery. Using a cat weighing 2-3 kg, I obtained specimens by infusing dyes in a living cat at various periods after operation. The results were as follows. 1) There were observed no dangerous symptoms by the ligation of the branch of the pulmonary artery. The necrosis of the ligated lobe did not occur. 2) Directly after the ligation there occurs a formation of a collateral pathway by a capillary communication from the vessels of the bronchial wall which extends to the wall of the alveolus, then by the newly built vessels which came outside the lobe through the adhesion with the peripheral area of it. 3) By ligation a thrombus will be formed in the pulmonary artery but a circulating pathway can be noticed inside the thrombus. This is considered to be a circulating pathway retrogradely to the pulmonary artery through the capillary net work of the alveolus wall by the vessels of the bronchial walls and the vessels which invaded from the outside of the lobe through the adhering portion. A week after the ligation the thrombus is nearly absorbed and the recovery of the circulation inside the pulmonary artery can be noticed. 4) The change of the lobe which occurs by the ligation of the branch of the pulmonary artery can be applied clinically

Performance improvement and cost reduction techniques for radio over fiber communications

Advanced cost reduction and performance improvement techniques conceived for Radio Over Fiber (ROF) communications are considered. ROF techniques are expected to form the backbone of the future 5G generation of wireless networks. The achievable link performance and the associated deployement cost constitute the most salient metrics of a ROF architecture. In this paper, we commence by providing a rudimentary overview of the ROF architecture and then elaborate on ROF techniques designed for improving the attainable system performance. We conclude by describing the ROF techniques conceived for reducing the ROF system installation costs