Jaap van de Beek

UHF white space in Europe — A quantitative study into the potential of the 470–790 MHz band

In this paper we study the availability of TV white spaces in Europe. We focus specifically on the 470–790 MHz UHF band that is still predominantly used for TV broadcasting also after the digital dividend (frequency reallocation as part of transition to digital TV), which has taken place or is ongoing in several European countries. We find that in the countries used in our studies, approximately 56% of the TV channels are unused, when averaged over the whole geographic area. Considering the average over population instead of geographic area reduced the mean available white space to 49% of the channels. Our results confirm quantitatively the often stated expectation that there are indeed fewer white spaces available in Europe compared to, for example, the United States. We also study the influence of different modeling assumptions on our results, especially focusing on the impact of the choice of propagation model. Our results show that changing from statistical ITU-R model to the Longley-Rice irregular terrain model does not cause a major change in the overall estimated availability of white spaces. However, changing the propagation model can significantly affect especially the local variability of the estimated availability of spectrum. This underlines the importance of using right system models in various studies before making too far-reaching conclusions.

Multiple Access with Low-Density Signatures

We present sets of spreading sequences that are specifically designed to suit a belief-propagation multiuser detection structure, recently presented for overloaded system scenarios. On one hand, our sequences are of the low-density type; on the other their distance spectrum properties ensure good performance in AWGN channels. Simulations results for raw and coded bit-error probability indicate that significant performance gain is achieved over random sequences and that the loss compared to the single-user bound can be kept small.

Orthogonal Multiplexing in a Subspace of Frequency Well-Localized Signals

A multiplexing scheme onto K OFDM subcarriers arranges M ≤ K dimensions to shape the signals transmit spectrum while the remaining K - M dimensions are used to orthogonally multiplex data symbols. This results in a new class of basis functions along with an equivalent precoder structure. In particular, N-continuous OFDM signals are realized as an orthogonal multiplex.

Constructing radio environment maps with heterogeneous spectrum sensors

In this demonstration proposal we describe a prototype of a radio environment map (REM) for storing and reasoning about spectrum data obtained from heterogeneous sources. The architecture of the REM prototype is both modular and extendible, and can be used with very diverse spectrum sensors, ranging from high-fidelity spectrum analyzers to dedicated low-cost embedded solutions. In the proposed demonstration we will illustrate how information such as transmitter locations and estimates of spectrum occupancy over space and time can be inferred and made available through the REM, based on information obtained from a network of different spectrum sensors deployed specifically for the demonstration.

EVM-Constrained OFDM Precoding for Reduction of Out-of-Band Emission

This contribution addresses the potential of N-continuous OFDM signals in systems where the receiver is unaware of the transmitter precoder operation. First, we present a memoryless precoder render ...

How a layered rem architecture brings cognition to today's mobile networks

In this article, we present a layered radio environment map architecture along with its applications to the self-organizing network functionalities of heterogeneous LTE radio access networks comprising macrocells and femtocells. In this architecture, the functional blocks reappear with different spatial and temporal granularity at different architectural layers. Although the radio environment map is one of the key promising technologies to enable future cognitive radio networks, it can be already applied to provide limited cognitive capabilities to todays commercial networks too. We explain why, and show how, this architecture can support today¿s LTE self-organizing network functions like automatic neighbor relation and minimization of drive tests, and also allow the smooth introduction of new radio access technologies through refarming. We also demonstrate some of the quantitative benefits adopting radio environment map technologies can bring using the minimization of drive tests as an example.

Design of layered radio environment maps for RAN optimization in heterogeneous LTE systems

In this contribution a layered radio environment map (REM) architecture is designed and applied in the framework of radio-access network optimization for heterogeneous LTE systems that comprise both macrocells and femtocells. We define layer as the hierarchical representation of a geographical area. In each layer, different instances of the same architectural block will have different spatial/temporal granularities, associated with network functionalities. The effectiveness of the proposed architecture to support LTE functions like automatic neighbor relation (ANR) and minimization of drive tests (MDT) is discussed. In addition, we present the benefits of using such architecture in the implementation of these functions along with its potential to bring performance gains.

REM-enabled opportunistic LTE in the TV band

In this demonstration paper we describe a prototype of an LTE system deployment that opportunistically exploits the spectral white spaces in the upper UHF TV bands, intelligently guided in its spectum access by a radio environment map (REM). The architecture is modular in the sense that interfaces are generic and minimal. In the proposed demo we will illustrate how information of primary transmitters and other secondary transmitters as well as estimates of the radio field strength over frequency, time and space can be made available and exploited by a secondary TDD-LTE base station to make judicious decisions on its spectral occupation.

5G in rural and low-income areas: Are we ready?

Current trends in telecommunication networks foresee the adoption of the fifth generation (5G) of wireless networks in the near future. However, a large number of people are living without coverage and connectivity. To face this issue, we consider the possibility of deploying 5G networks in rural and low-income zones. After detailing the current state-of-the-art, we consider the main challenges that need to be faced. Moreover, we define the main pillars to follow in order to deploy 5G networks in such zones, as well as a proposal of a future network architecture.

Simple distributed interference source localization for radio environment mapping

In order to construct a radio environmental map that can help navigating secondary communication in TV bands, we present a new method of interference source localization for cognitive radio networks. Our low-cost, high-precision localization method, operates without any prior knowledge of the interference source other than transmitter power. It can be divided into two steps: an estimation step at each sensor based on classical methods to estimate the angle of arrival and the received signal power, followed by an SNR-aided fusion. Simulation results show that tens of sensor nodes each having two antennas in a large-scale area setting are enough to achieve accurate location. The proposed location method is practical, economic and essential for blind interference source localization in cognitive radio networks.