Egon Schulz

Multi-carrier waveform based flexible inter-operator spectrum sharing for 5G systems

This paper presents a multi-carrier waveform based inter-operator spectrum sharing concept for 5G mobile and wireless communication systems. The proposed concept considers the flexible air-interface being developed for 5G and can support coordinated inter-operator spectrum sharing in various scenarios, including mutual renting, spectrum spot market, co-primary sharing, licensed shared access (LSA), secondary horizontal sharing etc. Compared to state-of-the-arts, the proposed concept has much broader applicability and less restrictions on infrastructure conditions, including radio access network (RAN) sharing, inter-operator synchronization and fast inter-operator signaling. Furthermore, the proposed concept allows high flexibility both in spectrum allocation and adaptation of the transmission signals to support the large variety of devices expected in 5G scenarios. The key elements of the proposed concept includes the determination of a common subcarrier grid, a two-stage allocation procedure, fragmented spectrum usage, usage of “out-of-fragment radiation masks”, and adaptation of multi-carrier waveforms. Preliminary results have shown that the proposed concept allows efficient and flexible fragmented spectrum usage, with robustness against inter-operator synchronization mismatch.

Double-directional and dual-polarimetric indoor measurements at 70 GHz

Double-directional, ultra wideband dual-polarized channel measurements at 70 GHz have been carried out in a small-office environment. The aim of these measurements is to study the temporal, directional, and polarization properties of the channel for modelling purposes of the future wireless communication systems at mm-waves. A highly deterministic behaviour of the channel and the environment has been identified, as well as the limitations of only parameterizing channel models as WINNER for the new mm-wave channel models.

Ultra-Wideband Channel Sounder for Measurements at 70 GHz

Owing to the limitation in bandwidth of currently used frequency bands, future fifth generation (5G) mobile networks will need to operate at higher frequencies. However, one important step in the research activities for the next generation of mobile networks is the broadband fully polarimetric analysis of the multipath propagation in dynamic single and multiuser scenarios under time-variant shadowing environments in millimetre- wave (mm-wave) channels. This paper presents a channel sounding campaign at 70 GHz in an urban outdoor scenario focusing on broadband channel characteristic at mmwave. For the measurements a novel dual-polarized (DP) ultrawideband (UWB) multi-channel sounder (DP-UMCS) architecture, developed at the TU Ilmenau for propagation measurements in cellular networks, was used to study the directional and polarization properties of the channel in view of the future wireless communication systems.

Characterisation of Channel Measurements at 70GHz in Indoor Femtocells

A wideband, fully polarimetric and directional radio channel sounding campaign conducted at 70 GHz is presented. Measurement site was chosen as an entrance hall, featuring femtocell size. Transmitter and receiver were placed according to an access-point scenario. Initial large-scale parameters like excess-delay, delay-spread and angular spread are derived for channel characterisation. It is not the papers goal to describe a new channel model. The main focus is the identification of propagation effects and characteristics, which have to be considered in future modelling. It was found, that first more specular than diffuse components occur and second the channel is spatially sparse.

Performance of coarse relay site planning in composite fading/shadowing environments

Relay deployments promise to alleviate the limitations of conventional macrocell networks, such as poor indoor penetration and coverage holes in a cost-efficient way. In this context, the capacity of the wireless relay link between a relay node (RN) and its serving base station (BS) has a crucial role in the achievable end-to-end performance. The deployment flexibility of RNs, which mainly stems from the wireless relay link, compact physical characteristics, and low-power consumption, can be exploited by relay site planning (RSP) to overcome the limitations of the relay link and, thus, enhance the system performance. To this end, RSP is carried out via selecting an RN deployment location from a discrete set of alternatives considering the signal-to-interference-plus-noise ratio (SINR) on the relay link as the selection criterion. In practice, the so-called coarse RSP takes into account only large-scale fading due to shadowing. Nevertheless, as RNs are stationary, the wireless channels pertaining to relay deployments are subject to simultaneous impairments by both shadowing and multi-path fading, i.e., composite fading/shadowing. In this paper, we present the performance of coarse RSP that can be used for planning and dimensioning of two-hop cellular relay networks in composite fading/shadowing environments, where co-channel interference is also present. The relay link is modeled by Nakagami-lognormal distribution while the access link between a mobile terminal (MT) and its serving RN is modeled by Rician-lognormal distribution. Furthermore, we provide an accurate analytical framework through closed-form expressions for relay link SINR, link rates, and end-to-end rate. Results show that coarse RSP can still yield high performance improvements considering composite fading/shadowing channels.

Practical Coarse Relay Site Planning: Performance Analysis Over Composite Fading/Shadowing Channels

Relay deployments promise to alleviate the limitations of conventional macrocell networks, such as poor indoor penetration and coverage holes in a cost-efficient way. In this context, the capacity of the wireless relay link between a relay node (RN) and its serving base station has a crucial impact on the end-to-end performance. The deployment flexibility of RNs, which mainly stems from the wireless relay link, compact physical characteristics, and low-power consumption, can be exploited by relay site planning (RSP) to overcome the limitations of the relay link and, thus, enhance the system performance. To this end, RSP is carried out via selecting an RN deployment location from a discrete set of alternatives considering the signal-to-interference-plus-noise ratio (SINR) on the relay link as the selection criterion. In practice, the so-called coarse RSP takes into account only large-scale fading due to shadowing. Nevertheless, as RNs are stationary, the wireless channels pertaining to relay deployments are subject to simultaneous impairments by both shadowing and multi-path fading, i.e., composite fading/shadowing. In this paper, we present the performance of coarse RSP that can be used for planning and dimensioning of two-hop cellular relay networks in composite fading/shadowing environments, where co-channel interference is also present. The relay link is modeled by Nakagami-lognormal distribution while the access link between a mobile terminal and its serving RN is modeled by Rician-lognormal distribution. Further, we provide an accurate analytical framework through closed-form expressions for relay link SINR, link rates, and end-to-end rate. Results show that coarse RSP can still yield high performance improvements in terms of both SINR and rate considering composite fading/shadowing channels. Moreover, coarse RSP is shown to effectively decrease the amount of fading on the relay link and, thus, mitigate the detrimental effects of composite fading/shadowing.

Cross-Device Signaling Channel for Cellular Machine-Type Services

The Machine-type services induce one critical challenge for the current cellular networks: The capacity of the conventional signaling channel in the network can hardly support the anticipated massive number of machine-type devices. According to the current network design, the signaling channel can easily be blocked up by a number of simultaneous signaling requests. In order to release the bottleneck of the signaling channel, we proposed a cross-device signaling mechanism to reduce the transmitted signaling data during the congestion-critical period. This mechanism removes the redundancy between the signaling messages of different devices. It has especially high performance when multiple highly synchronized devices generate simultaneous signaling requests. Thus, the mechanism can effectively mitigate the potential congestion in the signaling channel and further increase the design capacity of the network.