Future Network & Mobile Summit 

Abstract: Channel state information at the transmitter (CSIT) can greatly improve the capacity of a wireless MIMO communication system. In a time division duplex (TDD) system CSIT can be obtained by exploiting the reciprocity of the wireless channel. This however requires calibration of the radio frequency (RF) chains of the receiver and the transmitter, which are in general not reciprocal. In this paper we investigate different methods for relative calibration in the presence of frequency offsets between transmitter and receiver. We show results of theses calibration methods with real two-directional channel measurements, which were performed using the Eure-com MIMO Openair Sounder (EMOS). We demonstrate that in a single-user MIMO channel and for low signal-to-noise (SNR) ratios, the relative calibration method can increase the capacity close to the theoretical limit.

Abstract: Small cell deployment is one of the most promising technology trends to cope with the rising need for very high data rates foreseen in future mobile networks. Nevertheless, it has the side effect of introducing more complex interference scenarios, needing to be properly managed by means of coordination mechanisms. The recently introduced Cloud-RAN architecture, based on centralized processing, enables the implementation of efficient interference prevention and cancelation algorithms across multiple cells. However, it struggles with the need of high-capacity front-haul links and cost-intensive deployments. This paper introduces the novel concept of RANaaS (Radio Access Network-as-a-Service) as a flexible architecture based on centralized processing, capable of handling the increasing interference in very dense networks, reducing energy consumption, cost-efficiently deploying and managing cellular networks.

Abstract: The area of activity recognition is essential for context-aware systems. Previous and current investigations demonstrate that the accelerometer is suitable for accurate movement and activity recognition. Since smartphones are used by people in their daily lives, they can be seen as an attractive sensor device for the purpose of activity recognition. In our work, experiments have been carried out to investigate the suitability of the built-in accelerometer by comparing the influences of classification algorithms, features and the combination of sampling rates and window sizes for features extraction have on the classification accuracy. Obtained results indicate that smartphones similar to the test device provide good accuracy in recognizing common movements.

Abstract: Mobile data traffic has been increasing at a rapid pace over the past few years due to the rise of both smartphones and tablets To accommodate such a huge traffic volume in cellular systems, it is imperative to reduce cell size to increase system capacity To reduce cell size, the main issue confronting mobile network operators is system cost to provide coverage areas with small cells Therefore, we propose a suitable RAN architecture for deploying small cells First, a base band is physically separated into one baseband unit (BBU) and remote radio heads (RRHs) The BBUs are centralized in some locations One BBU can connect to one or more RRHs Such a network architecture, which we call Colony-RAN due to its ability to flexibly change cell layout, can dynamically change the connections of BBUs and RRHs in respect to traffic demand As a result, because traffic distribution is non-uniform, Colony-RAN can drastically reduce the number of BBUs due to the statistical multiplexing effect As a rough estimation based on the population of the Tokyo metropolitan area, we confirmed that the number of BBUs can be reduced by 75% with the co-located BBU and RRHs compared with conventional cellular systems Another characteristic of Colony-RAN is its ability to reduce inter-cell interference and increase link quality by accommodating several RRHs in the same BBU taking user mobility and/or user distributions into consideration