UTRA/FDD RF Transceiver Requirements

Unified RF requirements are derived for an UMTS Terrestrial RadioAccess/Frequency Division Duplex (UTRA/FDD) compliant mobile transceiver. Aset of transceiver requirements are proposed with consideration to systemissues including duplex aspects. From these design-compatible requirements areproposed for each functional block in the transceiver.     

A four-step method for de-embedding gigahertz on-wafer CMOSmeasurements

In this paper, a de-embedding method is proposed for conducting accurate on-wafer device measurements in the gigahertz range. The method addresses issues of substrate coupling and contact effects and is therefore suitable for measurements with lossy technologies such as CMOS. The method assumes a probe-tip two-port calibration performed with well-known techniques and impedance substrates. By employing a physical interpretation of the test-fixture, the method alleviates a number of known problems with common de-embedding procedures. Four distinct mathematical steps are suggested to de-embed parasitics for the test-fixture to give an accurate measurement of the device under test. By introducing a simple compensation factor for in-fixture standard imperfections, the proposed method allows large devices to be measured with high accuracy. The applicability of the method is demonstrated with measurements up to 12 GHz     

Effects of Dominant Other-Sector Interference on Dual Rx-Antenna HSDPA Performance

Link level SINR simulation results and network level sector throughput simulation results that quantify the benefit of dual antenna MMSE reception in a macrocellular WCDMA/HSDPA system are provided. Dual antenna RAKE receiver performance serves as baseline reference. Link-level simulation results are accompanied by a novel analytical expression that in flat Rayleigh fading and for uncorrelated rx-antenna branches describes spatial interference suppression mean SINR gain as function of a dominant other-sector interference ratio (DIR). It is shown that the MMSE receiver’s spatial interference suppression gain heavily depends on the amount of experienced DIR. The higher the DIR the higher the SINR gain. Nevertheless, seen on network level the SINR gain turns into moderate sector throughput gain, well below 50%. This is due to the fact that high DIR situations are rare in the investigated macrocellular scenario. Moreover, the logarithmic relation between SINR and capacity hinders translation of the full SINR gain into HSDPA sector throughput.     

An overview of downlink radio resource management for UTRAN long-term evolution [Accepted from Open Call]

Radio resource management algorithms ranging from bearer admission control to semi-persistent and dynamic packet scheduling, fast link adaptation, and transmission control of multiantenna transmission modes are addressed in this article for UTRAN long-term evolution. First, a high-level system overview of LTE is given, with special emphasis on the important components related to RRM. The quality of service parameter framework is outlined, as one of the main objectives for the families of RRM algorithms is to maximize system capacity while serving all users according to their minimum QoS constraints. It is demonstrated how the collocation of the RRM algorithms at the base station with easy access to air interface measurements offers opportunities for efficient cross-functional optimization between layers 1, 2, and 3. Examples of performance results for different traffic mixes and antenna transmission schemes are also presented, and the article is concluded with recommendations on how to operate the various RRM options under different load and traffic conditions.     

Implementation aspects for successive interference cancellation in DS/CDMA systems

This paper addresses the practical implementation of Successive Interference Cancellation (SIC) for DS/CDMA systems. The practical aspects of such an implementation are discussed and a convenient pipelined architecture is presented. An important aspect is the integration of power control (PC) and interference cancellation which has synergistic effects of optimizing the SIC, reducing intercell interference, and facilitating the implementation. This revised version was published online in July 2006 with corrections to the Cover Date.     

EM-Simulation of Planar Inductor Performance for Epitaxial Silicon Processes

We used a 2.5D EM-simulator to study planar inductor performance in a submicron CMOS technology. We found good agreement between simulations and measurements using only the nominal process parameters for the layer thicknesses, permittivities, and conductivities. By sweeping the thickness and conductivity of the epitaxial layer we show how these parameters affect inductor performance. The presence of a highly conductive substrate layer is shown to have a detrimental effect on inductor performance whereas the thickness and conductivity of the epitaxial layer is less important.     

Selecting indicators to assess the fisheries of Lake Malawi and Lake Malombe: Knowledge base and evaluative capacity

The provision of management information on the fisheries of Lakes Malawi and Malombe has been characterised by top–down controlled single species steady-state assessment techniques originating from single gear industrial fisheries but applied to an open access highly diverse and adaptive small-scale multispecies and multi-gear fishery. The result has largely been an unhappy marriage with uncertainties blamed more on the data than the process, although the data collection generally is detailed and comprehensive on catch and effort parameters. An extensive literature review of primary and grey literature on ecosystem drivers, exploitation pressures, and fish population and community states shows that Malawi has the necessary knowledge base for expanding their assessment into multi-causal and exploratory indicator-based methods that can assist in better understanding and more disciplined use of existing data and monitoring systems. Selection and ranking of a suite of indicators focusing on the major fisheries in the Southeast arm of Lake Malawi and Lake Malombe were done by a group of Malawian fisheries researchers and management advisers, thereby testing a framework of scoring criteria assessing an indicator's acceptability, observability, and relatedness to management. Indicators that are close to raw observational data and that require limited permutations and few assumptions appear to be preferable in the Malawian context. CPUE-based assessments can improve the utility of data and information in communicating developments and processes and evaluate fisheries management policies.     

Water level fluctuations and the ecosystem functioning of lakes

Hydrological regimes are key drivers of productivity and structure in freshwater ecosystems but are increasingly impacted by human activity. Using 17 published food web models of 13 African lakes as a case study, we explored relationships between seasonal and interannual water level fluctuations and 15 attributes related to ecosystem function. We interpreted our results in the context of Odum's ecosystem maturity hypothesis, as systems with higher magnitude fluctuations may be kept at an earlier maturity stage than those that are relatively stable. The data we compiled indicate that long-term changes in the hydrological regimes of African lakes have already taken place. We used Least Absolute Shrinkage and Selection Operator (LASSO) regression to examine relationships between ecosystem attributes and seven physical characteristics. Of these characteristics, interannual water level fluctuation magnitude was the most frequently retained predictor in the regression models. Our results indicate that interannual water level fluctuations are positively correlated with primary and overall production, but negatively correlated with fish diversity, transfer efficiency, and food chain length. These trends are opposite those expected with increasing ecosystem maturity. Interestingly, we found seasonal water level fluctuations to be positively correlated with biomass. An increase in standing biomass is generally associated with more mature ecosystems. However, we found that less production and biomass occurred at high trophic levels in highly fluctuating compared to relatively stable systems. This synthesis provides evidence that water level fluctuations are a key process influencing ecosystem structure and function in lakes.