Section: New Results

Flexible Radio Node

Radio wave propagation

The MR-FDPF (Multi-Resolution Frequency Domain Partial Flow) method is proven to be a fast and efficient method to simulate radio wave propagation. It is a deterministic model which can provide an accurate radio coverage prediction. In reality, radio channels have the nature of randomness due to e.g. moving people or air flow. Thus they can not be rigorously simulated by a pure deterministic model. However, it is believed that some statistics can be extracted from deterministic models and these statistics can be very useful to describe radio channels in reality. In [20] , large scale fading statistical characteristics are extracted based on the MR-FDPF method. They are validated by comparison to both the theoretical result and measurement. The match also demonstrates that MR-FDPF is capable of simulating large scale fading.

In [2] we study Realistic Prediction of Bit error rate (BER) and adaptive modulation and coding (AMC) for Indoor Wireless Transmissions. Bit error rate is an important parameter for evaluating the performance of wireless networks. In this letter, a realistic BER for indoor wireless transmissions is predicted. The prediction is based on a deterministic radio propagation model, the MR-FDPF model, which is capable of providing accurate fading statistics. The obtained BER map can be used in many cases, e.g., adaptive modulation and coding scheme or power allocation.

In [4] , we propose a modification of the MR-FDPF method that allows simulating radio propagation channels in a frequency range. The performance of the proposed MR-FDPF implementation has been analyzed based on different realistic propagation scenarios. We also analyze the possibility of applying the multi-resolution frequency domain approach to the well-known transmission-line matrix method. The proposed multi-resolution frequency domain transmission-line matrix method provides a computationally efficient way of modeling radio wave propagation in three dimensional space at multiple frequencies.

In [3] , we consider the performance of coded wireless communication systems experiencing non-frequency selective fading channels in shadowed environments. The quality of service (QoS) in a wireless network is dependent on the packet error outage (PEO). We address the problem of finding a tractable expression for the coded PEO over Nakagami-m channels with shadowing, considering multilevel modulations, various block, convolutional channel coding schemes and hard decision decoding. In order to obtain the coded PEO, an inversion of the coded packet error probability (PEP) w.r.t. the signal to noise ratio (SNR) is needed. To this end, we propose an invertible approximation for the coded PEP w.r.t. the uncoded bit error probability (BEP) in Nakagami-m fading channels which is accurate for all BEPs of interest. The BEP itself depends on the average SNR and we hence make use of previous results on the inversion of the uncoded BEP w.r.t. the SNR in Nakagamim fading channels, holding for M-PSK and M-QAM signals. We were thus able to obtain a reliable closed form expression for the coded PEO in flat fading and shadowing channels

Power consumption

In [24] , we propose the use of an existing opensource network simulator, wsn et, to evaluate the interest of using multi-mode relays in terms of energy consumption. We show that the combination of mimo and multi-mode provides a solution to reduce global energy consumption, but that conclusions are really scenario-dependent. Moreover, we explain how a multi-mode mimo terminal can improve these results using adaptive strategies.

the energy consumption in wireless sensor networks is studied. In order to minimize the consumed power at the analog and RF part, an energy recovering system combined with a wake-up radio is proposed for discussion. The proposed architecture has three activity levels : zero consumption, low and high energy consumption. In order to quantify the gain in terms of power consumption, a power consumption model state of the art is proposed. in [7] all radio channel models which can be used for mimo heterogeneous network with small cells are described.

MIMO

In [28] , we study mimo and next generation system. For the past decade or more mimo systems have been the subject of very intensive research. However in the past few years, these techniques have begun to be implemented in practice. In particular they have appeared in the standards for next generation systems such as lte , 3gpp-lte Advanced and WiMAX, as well as the latest versions of Wifi. This chapter, extracted from the book edited by the Cost Action 2100: “Pervasive Mobile and Ambient Wireless Communications”, brings together the mimo systems used in next generation systems with other work on the implementation and simulation of these systems. It also describes advances in mimo techniques in a number of areas. The first section is divided into two sub-sections dealing first with simulators and testbeds which are used in system-level simulators to evaluate overall system capacity, as discussed in later chapters of this book. Secondly the development of terminals for next generation mimo systems is considered, especially considering the additional RF hardware required for mimo . Section 7.2 then discusses especially precoding techniques used in many of the recent standards to implement mimo . In particular precoding allows the implementation of closed loop or adaptive mimo . In next generation systems there is also much increased attention on mu -mimo and on multi-terminal mimo in general, including so-called “network mimo ” approaches, which appear in LTE as Coordinated Multiple Point: this is covered in Sect. 7.3. Various advanced mimo transmission and detection approaches are covered in Sects. 7.4 to 7.6, including some interesting work on mimo techniques involving continuous phase modulation, giving advantages in terms of peak-to-average power ratio.