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In this paper, we proposed random resource allocation using water filling for Light Fidelity (LiFi) system, namely Water-Filling Random Resource Allocation (W-FRRA). This paper assumes that the room has several things that can be reflected or absorbed the light from LED bulb and produce blocking probability. We consider that users always move and change, randomly in a room. We use 4x4x3 m for room dimension and power bias 1 W to transmit power for the first time. Power control is used to organise signal to noise ratio (SNR) for equality data rates in any user locations. Our simulation shows that after employee W-FRRA, all of users has similarity data rates around 90Mbps for any propagations distance. After equality data rates are achieved using power allocation, we concentrate for limited time-slot resource, unpredictable packet edge and consider to using Non-Orthogonal Multiple Access (NOMA) for increasing the throughput of LiFi. To prove that our proposed method has improve, we compare random packets transmission such as Slotted ALOHA (SA) and Contention resolution diversity slotted ALOHA (CRDSA). We validate the results using packet loss rate and throughput performances based on computer simulation. We found that W-FRRA has highest performance among SA and CRDSA with most number of user can be served. In addition, the throughput performance of W-FRRA has higher around 10% and 30% than CRDSA and SA, respectively. We also prove that our proposed has fairness system and already employee NOMA to serve users without collision for every location on LiFi system.

The fifth generation (5G) network introduce D2D communications on cellular network. On D2D system, the device can communicate each other directly without using the eNB, with limited range. This D2D network can be superimposed on LTE cellular network and will use same resources with the existing cellular users. The interference will happen between D2D users and the existing cellular users. To maintain the system performances, the resources allocation process become the important aspect, because of the interference among users. This work proposed joint-greedy algorithm, a greedy based allocation algorithm to assign the resources to D2D users for communications process. Join-greedy algorithm consists of two phase of sorting to find the best resource for each D2D users. The first sorting process is to find the best resource for each D2D user, and the second sorting process is to find the best solution from first process result. From the simulation process, the proposed algorithm can improve the spectral efficiency up to 0.309 bps/Hz, and improve the energy efficiency by 12.67 kbps/Watt. The proposed algorithm also can maintain the fairness among D2D pair. Join greedy algorithm has the average fairness index 79.05%. This prove that the proposed algorithm has better system performances compared with the other algorithm.

To improve performance in the 64-QAM multicarrier communication system, we propose a new method, closed-loop rotate modulation. The closed-loop process requires feedback channel information in the form of complex quantities that contain information on the gain and delay of the channel. Based on the purpose of distortionless transmission, we can get the equation in the closed-loop rotate modulation method on the multi-carrier system at the transmitter side. From the simulation results, with the application of closed-loop rotate modulation, the output signal of the multicarrier demodulator is exactly the same as the transmission signal. On the probability of error curve generated, the application of closed-loop rotate modulation can coincide with the system performance if only disturbed by the AWGN channel. Terms so that the algorithm can work optimally, the speed of updating feedback must be faster than changes in channel fluctuations and channel feedback works perfectly. The simulation results also show that although channel information feedback is not perfect, but still can produce a good performance, the more accurate channel feedback will result in a better probability of error. Another advantage of the scheme that we propose is that the transmission process of a multi-carrier system does not use guard intervals, so the efficiency of the data is maximized.

The energy consumption level become a new consideration in resources management scheme. This works proposed power transmit allocation using waterfilling method combined with proportional fair allocation algorithm on Multiple Input Multiple Output (MIMO) 2×2 OFDMA system. Waterfilling power allocation is a scheme that try to optimize the energy consumption level by giving more transmit power to user that has bad channel condition, and less power to user that good channel condition. The purpose of this waterfilling scheme is to decrease the energy consumption level of the system. This waterfilling power allocation performed on the system after proportional fair allocation algorithm. The proposed system (waterfilling-proportional fair algorithm) is compared with basic proportional fair algorithm with equal power allocation (EPA). Both are tested on varied user and cell radius. Simulation shows that, proposed waterfilling scheme give improvement in fairness by 4.12% and decrease transmitted power by 11.84% or 4.74 watt.

Device-to-device (D2D) communication not only expected to leverage the energy efficiency in the devices side but also on the network side. The previous works usually only address the energy efficiency of device discovery, which is an important process in D2D, in device side. In this work, we addressed the energy-efficiency of a network element during D2D device discovery. First, we adapted energy calculation for base station energy efficiency in independent device discovery. Second, we also adapted energy calculation for base station energy efficiency in network-assisted device discovery. Third, we conducted simulation to examine base station energy efficiency in both cases. Our simulation result shows that base station energy efficiency can be maximized by utilizing independent device discovery with multiple CHs in a cluster.

The LTE (Long Term Evolution) technology is expected to offer a number of distinct advantages over other wireless technologies. Scarcity of spectrum had encouraged regulator and provider to refarmed the spectrum. Spectrum refarming for LTE in 900MHz, 1800 MHz or 2100 MHz frequencies band is considered to trigger the potential degradation of existing services such as GSM and UMTS. The simulation's results decribe that in those frequencies band options, LTE can well coexist with other technologies in the ecosystem such as GSM and UMTS. Overall simulation results show that at 1800 MHz while LTE is interfered by LTE and others such as GSM and UMTS, the performance is lower than other frequencies, so the best option is at 900 MHz or 2100 MHz of the frequencies.

In this paper, the authors propose a novel Cluster Head Rotation method to spare the cluster head burden in energy consumption. The clustering method, which is a state-of-the-art approach in D2D communication, is expected to reduce the devices’ energy consumption. However, this method may induce significant energy burden for cluster head, which can bring significant disproportion in cluster head and cluster member energy consumption ratio. The authors performed several simulations to prove the eminence of Cluster Head Rotation. According to our simulation, Cluster Head Rotation achieve a better balance in energy consumption (1.25:1 for CH:CM) compared to standard clustering method (3:1 for CH:CM). Furthermore, the overall energy consumption of Cluster Head Rotation is also 75% lower than standard clustering method.

Long Term Evolution Advanced (LTE-A) is a promising technology to achieve peak data rate of up to 1 Gbit/s in the downlink and 500 Mbit/s in the uplink. Because adjacent cells employs the same frequency in universal frequency reuse scheme, interference between adjacent cells may degrade the bit rate, particularly at the cell edges. Inter-Cell Interference Coordination (ICIC) based on carrier aggregation as well as Coordinated Multipoint (CoMP) transmission and reception techniques have been considered as promising techniques to overcome the interference problem and to improve the bit rate at the cell edges. ICI problem can be mitigated by using different arrangements of frequency-bands allocations and possibly with different transmission power, distinguishing between the cell centre and the cell edge users. In this paper, mitigation of inter-cell interference using carrier aggregation (CA) and coordinated multipoint (CoMP) techniques are evaluated through computer simulaton. The simulation employs different frequency allocation schemes, fractional frequency reuse, different transmission powers, and different radio resource scheduling algorithms to evaluate and to enhance cell edge performance, bandwidth efficiency and throughput. The performance is evaluated in terms of SINR as a function of the number of femtocell users, and the separation distance from interfering cells. The performance is then compared between conventional technique, CA technique and the combined CA and CoMP techniques.

In this paper, utilizing user-order chunk allocation algorithm for OFDMA systems using carrier aggregation environment is proposed and evaluated. Chunk allocation algorithm is performed based on mean greedy algorithm which has low complexity. In order to adopt this algorithm to those system, all users are divided into a certain group in accordance with the number of available aggregated carriers. The simulation results are shown that the performance and time complexity of the proposed scheme is same with the system without user grouping. Therefore, the proposed scheme could be considered to realize in LTE-Advanced platform.

Clustering and cooperative clustering method in D2D communication, a promising technology for 4G and 5G communication, will decrease energy consumption in mobile communication. The novelty of this work is we analyzed the impact of variation in number of mobile terminals in one cell, data transfer rate, and number of cluster members in one cluster for energy consumption. Clustering and cooperative clustering method, which are two sophisticated methods for D2D communication, are expected to make D2D communication more efficient in energy consumption. Energy efficiency of devices was examined through several simulations. The first simulation, we studied the impact of different number of mobile terminals per cell for energy efficiency. The result shows that cells with a greater number of mobile terminals has higher mobile consumption. Furthermore, compared with other cells, a cell with cooperative clustering method has less energy consumption. Secondly, we also examined the impact of different data transfer rate for devices energy consumption. The result shows that energy consumption rate is decreasing exponentially along with the increment of data transfer rate. Finally, we investigated the impact of different number of cluster members per cluster. The result informs that in the scenario with clustering method, the variation in the number of MT per cluster relatively did not affect energy consumption. However, in the scenario with cooperative clustering method, each one increment of number of mobile terminals per cluster increase energy consumption approximately by 25%.

LTE-Advanced and Femtocell are deployed by cellular operators to improve the coverage and capacity to respond the demand for higher data rates in wireless networks. Integration of femtocell into cellular network faced interference between femtocell and macrocell. Several scenarios based on Fractional Frequency Reuse (FFR) methods have been proposed to mitigate this interference, including integer fractional fraction reuse (FFR), soft frequency reuse (SFR), frequency frequency reuse orde-3 (FFR-3) and optimal static fractional frequency reuse (OSFFR). The study proposes Distributed Fractional Frequency Reuse scenario to mitigate interference and improve performance simultaneously. Distributed fractional Frequency reuse (DFFR) is an improvement of OSFFR by allocating sub-bands proportional and it is reused for each sector.

In this paper, two algorithms in resource allocation with fractional power control scheme are proposed and evaluated. In these algorithms, we joint chunk allocation and unequal power allocation in one chunk by considering fractional power control scheme as power constraint on each user to improve the sum of spectral efficiency of users and fairness among users. In order to evaluate our proposed algorithms, we compare the performances of our proposed algorithms with those of the previous algorithms with fractional power control scheme as power constraint in each user. From the simulation results are shown that our proposed algorithms can improve the sum of spectral efficiency and fairness among users in macrocell urban and suburban condition.