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Quorum sensing (QS) is a bacterium-to-bacterium communication mechanism that uses signaling molecules called autoinducers (AI). However, such mechanism is not well defined yet due to its inherent complexity and energy constraints. We construct a communication network with the QS mechanism and analyze the average uplink channel capacity and bit-error-rate performance of the proposed system model over...
In this paper, a multi-cell joint optimization scheme based on pilot allocation is proposed in order to mitigate pilot contamination for multi- cell massive MIMO systems. This method measures interference of each pilot sequence caused by users multiplexing from adjacent cells exploiting the massive MIMO characteristics of fading channels. The scheme takes jointly optimizing a plurality of cells into...
This paper investigates the Gaussian state-dependent Z-interference channel (Z-IC), in which two receivers are corrupted respectively by two correlated states that are noncausally known to transmitters and unknown to receivers. Three interference regimes are studied, and the capacity region or sum capacity boundary is characterized either fully or partially under various channel parameters. The impact...
We investigate the global throughput maximization of distributed spectrum reusing (DSR) in cognitive radio (CR) network, which reaches the two-dimensional spectrum multiplexing. Most previous works only consider the temporal-domain accessing, which greatly underutilize the spectrum resources. In this paper, we propose a new temporal-spatial spectrum reusing scheme by fully exploiting the location...
Massive MIMO technology can increase capacity, data rate, and link reliability significantly without additional bandwidth or transmission power. Most of the previous study on Massive MIMO systems are using low frequency (2.6 GHz). This frequency is not suitable for future broadband technology, because IoT devices will use high frequency and possible cell coverage would be smaller. This work proposes...
In this paper, we consider a cognitive radio system, consisting of a primary user (PU), a secondary user (SU) transmitter, and a SU receiver. The SUs are equipped with directional antennas. The SU transmitter first performs spectrum sensing (with errors) and then transmits data. We assume the SU and PU can coexist and the SU transmits at two power levels, according to the result of spectrum sensing...
In this paper, we propose the new scheme, multi-user full-duplex MIMO (Multiple-Input and Multiple-Output) system, which performs uplink and downlink signal transmissions at the same frequency and time between the base station and multiple terminals. We show the characteristics of the transmission capacity of the proposed full duplex MIMO system by use of the channel information measured in an actual...
This paper proposes a simple coordinated multipoint (CoMP) transmission method for taxi radio systems in order to prevent inter-cell interference (ICI) without a significant renewal of facilities. The proposed method takes advantage of the interesting property that the ICI which is essential for CoMP can be represented by the communication distance easily obtained from vehicle position information...
Although Fractional Frequency Reuse (FFR) is a good solution for Inter-Cell Interference (ICI) problem, combined FFR and beamforming can be utilized for more improved cellular system performance. In this paper, we consider a hexagonal cellular network, where we derive the Downlink (DL) worst case Signal to Interference Ratio (SIR) closed form formula for three different beamforming techniques (horizontal,...
Nowadays, the use of Wireless Sensor Networks (WSN) is gaining popularity especially in dense urban scenarios with a wide range of applications which share the same ISM band of the spectrum frequency, this situation leads to severe congestion problems. Therefore, it is important to define mechanisms that allow the use of their resources in an efficient way maintaining system quality even under harsh...
The objective of this presentation is to illustrate that the principle of superposition of power is not always valid in electrical engineering and hence not applicable to analysis of multi antenna systems where multi-streams are affected by mutual interference. In electrical engineering, it is the voltage and the current that always can be superposed and that is why another name of it is field theory,...
Dense urban zones with high concentration of Wireless networks can degenerate in problems such as spectrum scarcity for devices in licensed bands, or high interference levels for devices in unlicensed bands, thus producing QoS problem. A possible solution to deal with this issue is the use of wireless devices to access opportunistically a licensed band. For this reason, this paper evaluates a channel's...
A channel capacity analysis is presented in this work for a spectrum-sharing cognitive radio link in which the fading experienced by the signal is modeled with the Hoyt (Nakagami-q) distribution. Based on a novel formulation of the squared Hoyt distribution derived by the authors, simple expressions for the capacity of the secondary link in a number of scenarios of interest are derived, which are...
This paper proposes a simple coordinated multipoint (CoMP) transmission method for taxi radio systems. The feature of the proposed method is to realize CoMP only by using the vehicle position information, which enables us to free from a significant renewal of facilities. The proposed approach is inspired by the idea that the channel capacity based on the inter-cell interference (ICI) can be represented...
In the underlay cognitive radio network, the secondary users are allowed to transmit concurrently with the primary users , which shows great potential to relieve the spectrum scarcity problem. However, it raises significant security issues at the physical layer due to the spectrum sharing approach. Different from most present research, in this paper we study the secure communication problem between...
This paper details novel methods to accurately estimate the achievable rates of channels with additive Gaussian mixture (GM) noise. Attention is paid to a Gaussian input and discrete inputs. Such discrete inputs represent a wide range of signaling strategies and include the capacity-achieving input as a special case. At first, we propose a simple technique to calculate the GM noise entropy. Specifically,...
This paper proposes an efficient method for combing multi-user MIMO (MU-MIMO) employing Tomlinson Ha-rashima precoding (THP) with semiorthogonal user selection (SUS). Although the ordering of MU-MIMO THP and SUS create space diversity benefit and multi-user diversity benefit, respectively, a significant computational effort is required, which is expected to be relaxed while retaining the system level...
In Physical Layer Network Coding (PLNC), since the two sources access the relay station at a time, the relay station can hardly demodulate each information owing to the mutual interference between two transmitted signals. The PLNC achieves the high secure relay communication based on physical layer security (PLS). The source needs the transmit power control based on the channel state information (CSI)...
Due to the increasingly scarce spectrum resources and densely deployed wireless networks, how to increase the spectrum utilization efficiency becomes a hot topic. Channel reservation and cooperative transmission have shown great potential to improve the spatial reuse and network capacity. However, it is difficult to avoid the shortcomings that simply adopting either scheme. In this paper, we propose...
Currently, the widely deployed Wi-Fi devices generally reside in three non-overlapped channels, resulting in severe co-channel interference and performance deterioration. The avoidance of using Partially Overlapped Channels (POC) is mainly because of the complicated interference effects among them, which has not been well studied. In this paper, we build an OpenWrt based Wi-Fi interference measurement...
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