Petri Luoto

Co-Primary Multi-Operator Resource Sharing for Small Cell Networks

To tackle the challenge of providing higher data rates within limited spectral resources we consider the case of multiple operators sharing a common pool of radio resources. Four algorithms are proposed to address co-primary multi-operator radio resource sharing under heterogeneous traffic in both centralized and distributed scenarios. The performance of these algorithms is assessed through extensive system-level simulations for two indoor small cell layouts. It is assumed that the spectral allocations of the small cells are orthogonal to the macro network layer and thus, only the small cell traffic is modeled. The main performance metrics are user throughput and the relative amount of shared spectral resources. The numerical results demonstrate the importance of coordination among co-primary operators for an optimal resource sharing. Also, maximizing the spectrum sharing percentage generally improves the achievable throughput gains over non-sharing.

Gibbs Sampling based Spectrum Sharing for Multi-Operator Small Cell Networks

To tackle the challenge of providing higher data rates within limited spectral resources we consider the case of multiple operators sharing a common pool of radio resources in the downlink. The goal is to maintain a long term fairness of spectrum sharing with a no coordination among small cell base stations. It is assumed that the spectral allocations of the small cells are orthogonal to the macro network layer and thus, only the small cell traffic is modeled. We develop a decentralized control mechanism for base stations using Gibbs sampling based learning techniques. Four algorithms are compared addressing the co-primary multi-operator radio resource sharing under heterogeneous traffic in both centralized and distributed scenarios. The performance of these algorithms is assessed through extensive system-level simulations for two indoor small cell layouts. The main performance metrics are user throughput and fairness between operators. The numerical results demonstrate that the proposed Gibbs sampling based learning algorithm provides considerably high throughput while ensuring fairness between OPs.

Performance evaluation of vehicular LTE mobile relay nodes

European Telecommunication Standards Institute (ETSI) is standardizing the 3GPP Long Term Evolution Advanced (LTE-A) relay nodes (RNs) which are intended to be used for providing enhanced cell edge coverage and capacity. We present simulation results on the prospected LTE-A mobile relay node (MRN) applications. The future vehicles can communicate with their environment by exchanging information with surrounding sensor networks and objects. This is related to the concept of Internet of Things (IoT), in which even the smallest objects are equipped with sensors and connectivity capabilities, in order to report information on, e.g., temperature and air pressure. We consider a scenario where in-car connectivity is provided by a short range wireless link such as Wi-Fi or Bluetooth, which can be utilized by the passengers, various sensors, or the vehicle itself. We study the achievable system performance improvement when MRNs are utilized in comparison with the case, in which the users are independently connected to the LTE network. Through simulations, we show that the wireless links via MRNs can give significant advantage when compared to the direct connections from personal handsets to LTE base stations (eNBs).

Bit-map based resource partitioning in LTE-A femto deployment

Self organizing network techniques are needed to manage serious two-tier interference in an ad hoc operation of dense femtocell deployment. This paper considers downlink frequency domain inter-cell interference coordination (ICIC) in femtocell deployment. The studied resource partitioning method works such that each active femtocell may adapt, determine, and advertise a so-called binary resource partition sequence indicating which physical resource blocks (PRBs) the femtocells may occupy for their current operation. The main idea is to avoid interference from neighbor femto access points (FAPs) and try to achieve guaranteed bit-rate to femto users. The considered coordination method requires only low rate, infrequent updates in stationary phase and enables ICIC in distributed self organizing manner. The resource partitioning strategies are simulated in an LTE compliant system level simulator. The system level results show that different resource partitioning methods provide substantial gain when MRC receiver is used. When LMMSE receiver is used gains are smaller but at least one of the resource partitioning methods provided a gain over the case without ICIC. Furthermore, it is shown that proposed method works in two different femto environments.

Energy efficient load sharing in LTE-A HetNets

This paper addresses energy efficiency and throughput performance of joint LTE-A macrocell and femtocell deployment. We consider two techniques discontinuous transmission (DTX) and offloading of users from macrocells to lower power femtocells. When the DTX is applied base stations delay transmissions until sufficient user data is available to transmit using 40 percent or more of the system bandwidth. This allows the base stations to remain inactive for larger periods of time, and therefore reducing energy consumption. The target is to reduce the overall network energy consumption per area with minimal impact to the throughput. The numerical results show that when the majority of macrocell users can be offloaded to be served by femtocells the mean power per area consumption will decrease by up to 34.7 percent and at the same time a larger portion of users are able to meet the intended throughput target. When DTX is applied energy consumption is reduced further still to 45.3 percent.

Performance evaluation of adaptive beamforming in 5G-V2X networks

Vehicles are the third fastest growing connected device type after smart phones and tablets. Also, automotive industry is interested to get more vehicles connected to the internet to improve traffic safety and efficiency. This creates a need for Vehicle-to-Everything (V2X) communications. In this work, the possibility of exploiting beamforming in LTE-V2X is considered. Singular value decomposition (SVD) receiver and precoder is implemented in an LTE-A system level simulator and the performance on multi-lane highway scenario is simulated and analyzed in downlink Vehicle-to-Infrastructure (V2I) scenario. The performance is compared to the conventional maximum-ratio combining (MRC) and LTE codebook precoded minimum mean square error (MMSE) receivers. In addition, the switched-beam beamforming is imitated by modified antenna patterns with 7 and 15 narrow beams. The results show that the SVD receiver provides gain compared to the conventional MRC and MMSE receivers in ideal scenario. Furthermore, with modified antenna patterns, the performance was enhanced when compared to the default antenna pattern.

Vehicle clustering for improving enhanced LTE-V2X network performance

Vehicle-to-Everything (V2X) communication holds the promise for improving road safety and reducing road accidents by enabling reliable and low latency services for vehicles. Vehicles are among the fastest growing type of connected devices. Therefore, there is a need for V2X communication, i.e., passing of information from Vehicle-to-Vehicle (V2V) or Vehicle-to-Infrastructure (V2I) and vice versa. In this paper, we focus on both V2I and V2V communication in a multi-lane freeway scenario, where coverage is provided by the Long Term Evolution Advanced (LTE-A) road side unit (RSU) network. Here, we propose a mechanism to offload vehicles with low signal-to-interference-plus-noise ratio (SINR) to be served by other vehicles, which have much higher quality link to the RSU. Furthermore, we analyze the improvements in the probabilities of achieving target throughputs and the performance is assessed through extensive system-level simulations. Results show that the proposed solution offloads low quality V2I links to stronger V2V links, and further increases successful transmission probability from 93% to 99.4%.

RF Driven 5G System Design for Centimeter Waves

5G system design is a complex process due to a great variety of applications and their diverse requirements. This article describes our experiences in developing a centimeter waves mobile broadband concept satisfying future capacity requirements. The first step in the process was the radio channel measurement campaign and statistical modeling. Then the link level design was performed tightly together with the radio frequency (RF) implementation requirements to allow as large scalability of the air interface as possible. We started the concept development at 10 GHz frequency band and during the project World Radiocommunication Conference 2015 selected somewhat higher frequencies as new candidates for 5G. Thus, the main learning was to gain insight of interdependencies of different phenomena and find feasible combinations of techniques and parameter combinations that might actually work in practice, not only in theory.

Configurable 5G air interface for high speed scenario

In fifth generation (5G) networks one target is to provide very high capacity wireless access for the places where a lot of people consume a lot of data. Wireless communication is needed to provide access to high moving vehicles, however, extreme velocities must be taken into account in the design. Specific problems for air interface design to support extreme velocities are: high Doppler shifts, Inter-Carrier Interference (ICI), and difficulties in channel measurements needed for demodulation and hand-over measurements. Furthermore, very high data rates on outdoor macro cellular environment is challenging due to path loss. In high speed train (HST) deployments, the presence of line-of-sight connection enables the usage of wide bandwidths that are available on cmWave and mmWave spectrum. In this paper, we investigate the performance of mmWave single frequency network (SFN) in HST scenario. The performance of orthogonal frequency division multiplexing (OFDM) transmission with different new radio (NR) parameters is analyzed. Especially, the effect of Doppler and cyclic prefix (CP) is analyzed. Moreover, we conduct link level simulations and analyze the spectral efficiency in ideal HST scenario. Results show that it is possible to achieve very high data rates up to 10 Gbps.

System level analysis of multi-operator small cell network at 10 GHz

Due to higher cost and spectrum scarcity, it is expected that an efficient use of spectrum in fifth generation (5G) networks will rather rely on sharing than exclusive licenses, especially when higher frequency allocations are considered. In this paper, the performance of a dense indoor multi-operator small cell network at 10 GHz is analyzed. The main goal is to show the benefits obtained at higher carrier frequency due to network densification while mobile network operators are sharing the spectrum. The analysis is assessed through extensive system level simulations. The main performance metrics are user throughput and signal-to-interference-and-noise ratio. Results show that when 10 GHz carrier frequency is used it allows higher network densities while satisfying user throughput requirements. However, when network is sparse lower carrier frequency leads to better performance. When network is dense, on average 2 Mb/s better mean throughput is achieved at 10 GHz when compared to traditional cellular frequency.