A review on current work in mobility prediction for wireless networks

The vision of next generation networks (4G & beyond) is to make possible seamless mobility across heterogeneous networks and to support real-time multimedia services. This would require intra/inter-domain handovers and service reconfiguration procedures to be completed with minimum latency. Mobility Prediction has been identified as a key abettor to this goal. The increasing ease of coupling between the mobile user and the network requires that a mobility prediction scheme that is to be deployed in next generation networks be capable of high levels of prediction accuracy despite randomness in user movement. In this work we have presented a survey on mobility prediction schemes that have been proposed for wireless networks. The results of our simulation study focused on the robustness of different schemes to randomness in user movement are also presented.

PAPR reduction technique for LTE OFDMA systems

Long term evolution (LTE) is the final step toward the 4th generation (4G) of radio technologies designed to increase the capacity and speed of mobile networks. LTE uses orthogonal frequency division multiple access (OFDMA) for the downlink transmission and single carrier-frequency division multiple access (SC-FDMA) for uplink. OFDMA meets the 4G requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates. However, the potentially large peak-to-average power ratio (PAPR) of the transmitting signals has limited its application. This high PAPR causes interference when the OFDM signals are passed through an amplifier which does not have enough linear range. In this article, we investigate a clipping based PAPR reduction method for LTE OFDMA systems. Simulation results show that the clipping method is reduced PAPR significantly which decreases as the number of clip and filtering level is increased. As a results, increase the mean transmit power, and improve the power amplifier efficiency. This comes at the outlay of complexity, efficiency as well as cost.

Micronutrient intakes affect early growth in extremely preterm infants : preliminary results from a Swedish cohort

Background: Extremely preterm infants generally experience postnatal growth failure. It is still unclear if this is related to micronutrient intakes.

Aim: To investigate the effect of micronutrient intakes (calcium, zinc, iron, phosphorus, sodium, potassium, chloride, magnesium, vitamin A, vitamin D, vitamin E, folate and vitamin B12) on growth during the first 28 days of life in extremely preterm infants.

Method: From the EXPRESS cohort (all infants born < 27 gestational weeks between 2004-2007 in Sweden), those who survived the first 28 days were included (n=524). Daily parenteral and enteral intakes and anthropometric measurements were retrieved from hospital records.

Results: Preliminary analyses of data from 333 infants (mean±SD gestational age 25.2±1.0 weeks, birth weight 753±168g) showed that macronutrient intakes were lower than recommended (energy 98±13kcal/kg/day, protein 2.9±0.4g/kg/day). Infants showed postnatal growth failure: mean standard deviation scores decreased by 2.2 for weight, 2.3 for length and 1.4 for head circumference. Intakes of micronutrients were generally low, e.g. adjusted enteral intakes of calcium were 66.6±21.4 mg/kg/day. The exception was iron, with a high parenteral intake of 2.7±1.6 mg/kg/day, mainly from blood transfusions. Adjusting for protein intake and other confounders, calcium intakes were positively correlated with head growth (r=+0.19, p=0.006) and iron intakes were negatively correlated with length gain (r=-0.18, p=0.009).

Conclusions: Low calcium intakes and high iron intakes were associated with poor growth with regard to head circumference and length, respectively. If these results are confirmed, optimized micronutrient intakes may improve early growth in extremely preterm infants.