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In this paper, measurements of the spectral occupancy in some high frequency (HF) bands in the Western part of Romania are presented. Signals have been acquisitioned by means of an Universal Software Radio Peripheral (USRP) equipment and spectrum occupancy values have been calculated off-line for a set of frequency bands that present interest for establishing of a system for emergency communications...
Results concerning joint Spectrum Availability (SA) monitoring in the 5–10 MHz range of the High Frequency (HF) band (3–30 MHz), for a 24-hour period, in two locations situated in the central and western part of Romania are reported. Measurements have been realized simultaneously in the two locations, with similar USRP SDR-based equipment, for 24 hours on February 27, 2017. Results indicate that SO...
Increasing the throughput per user while providing load balance are the main challenges in Heterogeneous Networks (HetNet) deployments. This paper focuses on influence of the two main concepts introduced by enhanced Inter Cell Interference Coordination (eICIC): Cell Range Extension (CRE) and Almost Blank Subframe (ABS) in multi tier HetNet architectures. Based on probabilistic models that characterize...
The ionospheric channel is time-variant and is affected by several factors such as variable attenuation, fading, modification of the polarization plane of waves, Doppler shift and nonlinearities. Therefore, communication channels through the ionosphere are subject to a high degree of variability. Nevertheless, communication through the ionospheric channel presents interest due to the modest requirements...
High frequency data transmission over short distances (few tens-few hundreds of km) is a valuable option for communication links in special/critical situations. Present experimental study of noise level and channel availability for digital multi-carrier modulated signals in the range 2.5–7.6MHz showed that reliable transmission is possible when signal to noise ratio exceeds 14dB and when receiving...
In this paper we explore uplink connection performances in a LTE Heterogeneous Network (HetNet). We perform a set of experiments in two different LTE HetNet configurations and focus on uplink coverage and capacity within an office building. The current results are obtained in single user equipment (UE) environment but the recommendation is valid also for multi-UE environment. The analysis is based...
In Long Term Evolution (LTE) networks handover performance is of high importance. In this paper we disseminate the results obtained during several handover experiments in LTE Heterogeneous Networks (HetNet) considering for handover trigger the A3 event and different parameters: Reference Signal Received Power (RSSP) and Reference Signal Received Quality (RSRQ). We also provide recommendations for...
This paper disseminates a set of results about Heterogeneous Network field trial experiments conducted in an LTE network at 2.6 GHz and focused on coverage within an office building. Two LTE metro cells deployed in indoor as well as LTE macro cells deployed in outdoor are considered. The later rely on small transmission power levels combined with easiest deployment of small cells. We considered an...
Voices Services over Adaptive Multiuser Channels on One Slot (VAMOS) is a 3GPP feature designed to increase GSM network capacity by multiplexing a pair of two users on the same time slot. The pairing problem consists of a proper choice of the two users depending to their radio conditions. We consider a pairing strategy based on necessary transmit power for downlink under the constraint of imposed...
The Voice services over Adaptive Multiuser channels on One Slot (VAMOS) feature has the potential to double voice capacity of the existing GSM mobile communication system while maintaining backward compatibility with the legacy system. The technical method of doubling voice channel capacity is based on Orthogonal Sub-Channel (OSC) approach that allows a single radio resource to support two independent...
VAMOS (Voice services over Adaptive Multi-user channels on One Slot) technique is the next step in the evolution of GSM voice services. The new method is based on the Adaptive QPSK scheme and VAMOS subchannel power control feature, which ensure that VAMOS is fully compatible with legacy mobiles. In this paper we propose a model for VAMOS network traffic. FR (full rate) and HR (half rate) users associated...
In this paper we implement and evaluate two scheduling techniques for mixed data traffic (VoIP and Video Streaming-VS) in LTE systems. We present results regarding resources allocation and traffic evaluation (mean throughput per user) for the Best CQI scheduler and compare to those for a Round Robin (RR) scheduler. Both services are delay-critical services but by prioritizing VoIP in the Best CQI...
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