Helga Dolorico Balbi

Bio: Helga Dolorico Balbi is an academic researcher from Centro Federal de Educação Tecnológica Celso Suckow da Fonseca. The author has contributed to research in topics: Wireless network & Handover. The author has an hindex of 1, co-authored 1 publications receiving 3 citations.

Ultra-high-bit-rate networking : From the transcontinental backbone to the desktop : Optical networks technology in Europe

Abstract: The advances in photonic device technologies are bringing ultra-high-bit-rate networking-at speeds towards 100 Gb/s and beyond-much closer to practical reality. It is increasingly likely that in the longer term ultrafast optical time-division techniques-together with wavelength multiplexing-will be used in networks at all levels, from the transcontinental backbone to the desktop. Examples of devices include a subpicosecond clock source packaged inside a laptop personal computer and an OTDM switch on a single semiconductor chip, both produced at HHI. Advances similar to these make it possible now to envisage the use of OTDM techniques, not just in the highest layers of national and international networks, but also much closer to the user-such as the world-first demonstrations at BT Laboratories of a 40 Gb/s TDMA LAN and a 100 Gb/s packet self-routing switch for multiprocessor interconnection. Ultrafast networks might even provide the interconnection backplane inside future desktop routers and servers with massive throughput.

CSIscan: Learning CSI for Efficient Access Point Discovery in Dense WiFi Networks

Abstract: Network densification through the deployment of WiFi access points (APs) is a promising solution towards achieving high connectivity rates required for emerging applications. A critical first step is to discover an AP before an active association between the client and the AP can be established. Legacy AP discovery procedures initiated by the client result in high latency in the order of a few 100 ms and waste spectrum, especially when clients need to frequently switch between multiple APs. We propose CSIscan that exploits the broadcast nature of WiFi channels by embedding discovery related information within an AP’s ongoing regular transmissions. The AP does this by intelligently distorting the transmitted OFDM frame by inducing perturbations in the preamble, and these injected ‘bits’ of information are detected via changes in the perceived channel state information (CSI). A deep learning framework allocates the optimal level of distortion on a per-subcarrier basis that keeps the resulting packet error rate to less than 1%. Existing clients perceive no changes in their ongoing communication, while potential new clients quickly obtain discovery information at the same time. We experimentally demonstrate that CSIscan reduces the overall WiFi latency from 150 ms to 10 ms and improves spectrum utilization with ~72% reduction in the probe traffic. We show that CSIscan delivers up to 40 discovery information bits in the outgoing WiFi packet in an indoor environment.

Handoff optimization for joint base station association and power control in uplink non‐orthogonal multiple access small cell networks

Abstract: This article investigates the handoff optimization in an uplink non‐orthogonal multiple access‐based small cell network (SCN) with successive interference cancellation that takes both the base station (BS) association and power control into consideration. Due to user mobility and varying communication environment, it is important to associate a user with the proper BS and control its transmit power by considering the user mobility for the SCNs. To overcome overly frequent re‐association and handoffs between BSs, a novel joint optimization of handoff, BS association, and total transmit power is presented that maximizes the system‐wide and handoff utilities and minimizes power consumption simultaneously. We define the handoff utility function by considering the BS association in each time frame with the previous time frame. Then, we formulate two inter‐related optimization problems under the minimum average‐rate and maximum allowable transmit power of mobile users (MUs) constraints. The designed optimization problems are combined through the weighted sum method into a single‐stage optimization problem. The transformed problem is solved by adopting the coalition formation game and primal decomposition theories. We design the coalition value function by collectively considering the handoff number of each BS in every time frame, transmit power of all MUs, and the number of associated MUs to every BS. The simulation results show the efficiency of the proposed handoff algorithm in comparison to another BS association algorithm in terms of the number of handoffs.