Joint detection and channel estimation for MIMO systems with SC-FDE modulations

SC modulation (Single-Carrier) with FDE (Frequency-Domain Equalization) allows excellent performance in severely time-dispersive channels, provided that accurate channel estimates are available at the receiver. For this purpose, pilot symbols and/or training sequences are usually multiplexed with data symbols, which lead to spectral degradation. As an alternative, we can use implicit pilots (i.e., pilots superimposed to data). In this paper we consider MIMO SC-FDE systems where the channel estimation is based on either explicit or implicit pilots, for comparison purposes. An iterative receiver with joint equalization, turbo decoding and channel estimation was employed for optimum results, and to reduce the high interference levels between data and pilots (for the implicit pilots). The main differences between the different schemes are discussed and the performance results show that the use of the proposed techniques for channel estimation yield excellent results.info:eu-repo/semantics/acceptedVersio

Performance bound for generalized M-QAM constellations in time-discrete multipath rayleigh fading channels with channel estimation errors

In this paper we derive a lower bound on the bit error rate (BER) for the individual bit streams that can be mapped simultaneously in an hierarchical way onto generalized multilevel quadrature amplitude modulations (M-QAM). The expressions are valid for time-discrete multipath Rayleigh fading environments with imperfect channel estimation and can be regarded as an extension of the well-known matched filter bound (MFB).info:eu-repo/semantics/acceptedVersio

Iterative decoding and channel estimation of MIMO-OFDM transmissions with hierarchical constellations and implicit pilots

In this paper we consider the use of M-QAM hierarchical constellations (Quadrature Amplitude Modulation) combined with implicit pilots for the transmission of multicast and broadcast services in a MIMO-OFDM (Multiple Input Multiple Output - Orthogonal Frequency Division Multiplexing) system. This method of pilot transmission allows coherent detection at the receiver while avoiding the spectral degradation associated with the usual pilot multiplexing techniques but results in mutual interference between pilots and data. Due to the demanding channel estimation requirements and the high sensitivity to interference resulting from the usage of several antennas and hierarchical constellations, an enhanced receiver based on the turbo concept is developed which is capable of dealing with the inherent interference between pilots and data.info:eu-repo/semantics/acceptedVersio

Efficient channel estimation for OFDM systems with hierarchical constellations

In this paper we consider the use of M-QAM hierarchical constellations (Quadrature Amplitude Modulation) combined with implicit pilots for the transmission of multicast and broadcast services in OFDM (Orthogonal Frequency Division Multiplexing) systems. This method of pilot transmission allows coherent detection at the receiver while avoiding the spectral degradation associated with the usual pilot multiplexing techniques but results in mutual interference between pilots and data. Due to the demanding channel estimation requirements and the high sensitivity to interference resulting from the usage of QAM hierarchical constellations, an enhanced receiver based on the turbo concept is developed which is capable of dealing with the inherent interference between pilots and data.info:eu-repo/semantics/acceptedVersio

Linseed essential oil - Source of Lipids as Active Ingredients for Pharmaceuticals and Nutraceuticals

Linseed - also known as flaxseed -, is known for its beneficial effects on animal health attributed to its composition, comprising omega-6 (linoleic) and omega-3 (α-linolenic) fatty acids, various dietary fibers and lignans, which have health benefits in reducing the risk of cancer and cardiovascular diseases, lowering the levels of LDL-cholesterol and relaxing the smooth muscle cells in arteries increasing the blood flow. Essential fatty acids from flax participate in several metabolic processes of the cell, not only as structuring components of the cell membrane, but also as storage lipids. Flax is consumed in the form of seeds (whole, milled or roasted), as an oil and as flour to provide basic nutrition. Flax can be considered a functional food. Several formulations containing flax are available on the market in the form of e.g. capsules and microencapsulated powders having potential as nutraceuticals for their beneficial effects on health. This paper revises the different lipid classes found in flaxseeds and their genomics. It also discusses the beneficial effects of flax and flaxseed oil and their biological advantages as ingredients in pharmaceuticals and in nutraceuticals products.info:eu-repo/semantics/publishedVersio

Iterative partial-cancelling MMSE algorithms for W-CDMA MIMO-BLAST systems

This paper focuses on the usage of an enhanced equalization-based receiver for WCDMA (Wideband Code-Division Multiple Access) MIMO (Multiple Input, Multiple Output) BLAST (Bell Labs Layered Space Time)-type systems. The receiver is based on the MMSE (Minimum Mean Square Error) algorithm coupled with an IPC (Iterative Partial Cancellation) scheme. The scheme is tested in both an uncoded and coded setting, using the UMTS (Universal Mobile Telecommunications System) HSDPA (High Speed Downlink Packet Access) standard as a basis, and the reference UMTS environments.info:eu-repo/semantics/acceptedVersio

Measurement of the degree of Polarization Entanglement Through Position Interference

We produce polarization entangled states with variable degree of entanglement for twin photons. Entanglement in polarization is coupled to entanglement in position that produces transverse coincidence interference fringes. We show both theoretically and experimentally that, due to this coupling, we can use the interference pattern to measure the polarization degree of entanglement.Comment: 5 figure

Transverse coloplasty pouch and colonic J-pouch for rectal cancer: a comparative study

OBJECTIVES: The introduction of the colonic J-pouch has markedly improved the functional outcome of restorative rectal cancer surgery. However colonic J-pouch surgery can be problematic and may present some late evacuatory problems. To overcome these limitations a novel pouch has been proposed: the transverse coloplasty pouch. The purpose of our study was to compare the functional outcomes of these two different types of pouches--the transverse coloplasty pouch (TCP) and the colonic J-pouch (CJP)--during the first 12 months postoperatively. PATIENTS AND METHODS: A prospective randomized trial was conducted in which a total of 30 patients with mid and low rectal cancer were submitted either to a transverse coloplasty pouch or a colonic J-pouch. Clinical defaecatory function was assessed and anorectal physiological assessment was carried out, pre-operatively and at 3, 6 and 12 months postoperatively, by means of a standard clinical questionnaire and by anorectal manometry. RESULTS: No statistically significant differences were found between the two groups regarding bowel function. The postoperative frequency of daily bowel movements was lower in the TCP group in all the phases of the study (3.9 vs. 4.1 at 3 months; 3.1 vs. 3.4 at 6 months; 2.1 vs. 2.8 at 12 months), the same occurring with fragmentation (33% vs. 40% at 3 months; 26.6%vs. 33.3% at 6 months; 7.1%vs. 14.3% at 12 months). Less urgency was also seen in the TCP group during the first 6 months (20%vs. 26.7%), with identical values at 12 months (14.3% vs. 14.3%). No significant differences were also found concerning incontinence grading and scoring, with TCP patients having less nocturnal leaks. At one year two CJP patients (14.3%) needed the use of enemas to evacuate the pouch and provoke defaecation, a problem never seen in TCP patients. The anorectal manometry data was similar in both types of pouches. The local complication rates were also identical in the two groups (20%); more anastomotic leaks were seen in TCP patients (13.2% vs. 6.6%), without reaching a statistical significance. CONCLUSION: The transverse coloplasty pouch has similar functional results but fewer evacuation problems than the J-Pouch, making it a safe and reliable alternative to the colonic J-pouch

Quantum key distribution with higher-order alphabets using spatially-encoded qudits

We propose and demonstrate a quantum key distribution scheme in higher-order $d$-dimensional alphabets using spatial degrees of freedom of photons. Our implementation allows for the transmission of 4.56 bits per sifted photon, while providing improved security: an intercept-resend attack on all photons would induce an error rate of 0.47. Using our system, it should be possible to send more than a byte of information per sifted photon.Comment: 4 pages, 5 figures. Replaced with published versio

Effective radio resource management for multimedia broadcast/multicast services in UMTS networks

WOS:000242097300001 (Nº de Acesso Web of Science)Broadcast and multicast offer a significant improvement of spectrum utilization, and become particularly important where information channels are shared among several users. Mobile cellular environments are expected to evolve with the technological approaches necessary to facilitate the deployment of multimedia services, such as streaming, file download, and carousel services. The perspective that video streaming in wireless networks services is an attractive service to end-users has spurred the research in this area. To provide for a video delivery platform in UMTS, the third generation partnership project (3GPP) addressed this problem with the introduction of the multimedia broadcast and multicast services (MBMS) in 3GPP Release 6. In this document we analyse several effective radio resource management techniques to provide MBMS, namely, use of nonuniform QAM constellations, multicode, and macrodiversity to guarantee the optimal distribution of QoS depending on the location of mobiles.info:eu-repo/semantics/publishedVersio