We present an approach to the schematic design and time-dependent simulation of microfluidic systems that are composed of basic components, such as pumps, channels, mixing junctions, and valves. For the schematic capture and the simulation, the Cadence Virtuoso design framework is employed, with the components modeled by Verilog-AMS. The pressures and flow rates are calculated with the help of the hydraulic analogy between electronics and fluidics. Signal flow quantities are used to express the flow of chemical concentration. Our focus is on systems employing chemofluidic transistors, i.e., hydrogel-based microvalves that facilitate autonomous flow control without the need for an external control unit. Our approach also covers layout editing by the use of programmed cells. The utility of the approach is exemplified by the successful top-down design of a chemofluidic oscillator circuit and by the functionally correct simulation of a chemofluidic SR flip-flop.

Mobile network operators are facing a challenging dilemma. While on the one hand they are committed to reducing their carbon emissions, and energy consumption, they are also required to continuously upgrade existing networks, ensuring that the relentless growth in data traffic can still be supported. In most cases, these upgrades increase the energy consumption of the network even further. This paper presents a nation-wide case study, based on a commercial network of a leading European operator, intended to provide a clear understanding of how the energy consumption of mobile networks is expected to evolve from 2012 until 2020. The study also considers an efficient network capacity evolution path, including base station equipment improvement forecasts.

We consider the application of a channel state information (CSI) based multi-user (MU) multiple input multiple output (MIMO) scheme to the downlink of 3GPP Long Term Evolution (LTE) cellular networks. For that purpose, we propose a novel feedback method for providing CSI to the base stations (BSs) based upon standard vector quantization techniques. Moreover, we introduce and compare different ways for additionally signaling information about the interference situation observed by a certain user equipment (UE) to its serving BS. Apart from the actual CSI itself, the interference information is essential for choosing appropriate precoders and particularly for facilitating an efficient link adaptation. The performance of the proposed scheme is thoroughly investigated for different parameter settings by means of extensive system-level simulations and it is shown that considerable performance gains can be obtained compared to standard LTE Release 8 networks, which support channel quality indicator (CQI) feedback only.

In current cellular networks base stations (BSs) usually perform independent scheduling without coordinating the resource allocation among different cells. This, however, often leads to high interference levels in cellular networks operating with universal frequency reuse, such as the 3GPP UTRAN Long Term Evolution (LTE). Coordinated scheduling between different BSs may mitigate this problem by taking interference from and to nearby BSs into account in order to avoid high interference situations, especially for user equipments (UEs) located near the cell-edge. For that purpose, we propose in this paper a novel interference-aware joint scheduling scheme based on proportional fairness for the uplink of a 3GPP UTRAN LTE system, where different BSs cooperate with each other via a fast backhaul network in order to jointly allocate frequency resources to the various UEs, taking the caused inter-cell interference into account. Furthermore, we propose an efficient method for dynamic interference coordination based on the standardized high interference indicator and we compare the achievable performance with this approach to a system with interference-aware joint scheduling. It is shown that our joint scheduling scheme outperforms a dynamic interference coordination scheme and that it yields significant gains over a conventional LTE Release 8 system without any interference coordination.

Cellular networks operating with a frequency reuse factor of one are often interference-limited. For that reason, base station (BS) cooperation techniques aiming at mitigating the effects of interference caused by simultaneous transmissions on the same frequency resources in nearby sectors may considerably improve the system performance. However, for that purpose generally high-capacity backhaul links are required, which are often not available in practice. A crucial factor for realizing such cooperative techniques in the short-term therefore is to develop efficient ways for reducing the backhaul load without significantly worsening the achievable performance. In this paper, we evaluate the performance of inter-site joint detection with reduced backhaul capacity requirements for the uplink of a 3GPP UTRAN Long Term Evolution (LTE) system, where different BSs cooperate with each other in order to jointly detect the signals transmitted by various users. By means of extensive system-level simulations, we show that with the proposed methods still significant performance gains may be realized over conventional systems-especially in terms of the cell-edge throughput-while the backhaul load can be considerably reduced compared to a system with full-complexity joint detection.

The interference situation in the uplink of cellular networks, such as the 3GPP UTRAN Long Term Evolution (LTE), is usually highly volatile since from one transmission time interval to the other different users might be scheduled in nearby cells, thus often causing completely different levels of interference. This unstable behavior of the interference generally has a negative impact on the performance of fast link adaptation schemes since there is always an inherent delay between the time when the link adaptation is performed and the actual data transmission. In order to partially mitigate this problem, we propose in this paper a novel approach for predicting the interference situation during the actual data transmission already in advance, so that the link adaptation process can be considerably improved. This is accomplished by exchanging scheduling information between a set of cooperating base stations combined with multi-cell channel estimation. The performance of the proposed scheme is evaluated by means of extensive system-level simulations and we show that significant performance gains may be realized this way.

We evaluate the performance of the uplink of a 3GPP UTRAN Long Term Evolution (LTE) system with intra-site cooperation, where different sectors belonging to the same site may cooperate with each other in order to improve the system performance. This represents an intermediate step towards general coordinated multipoint (CoMP) systems as currently under discussion for LTE-Advanced, where a cooperation might take place even between sectors belonging to different sites. In contrast to general CoMP systems, however, intra-site cooperation as considered here is already feasible with LTE Release 8 and generally does not suffer from any restrictions due to limitations of the underlying backhaul network. In this regard, we consider both joint detection as well as joint link adaptation and we investigate the achievable performance for various cases by means of extensive system-level simulations. It is shown that intra-site cooperation may yield significant performance gains compared to conventional systems at reasonable complexity, thus making it a suitable approach for implementation in real-world networks.