Inter-cell Interference Mitigation Techniques Research Articles

A REVIEW OF INTER CELL INTERFERENCE MANAGEMENT IN REGULAR AND IRREGULAR GEOMETRY CELLULAR NETWORKS

This paper reviews the inter-cell interference (ICI) mitigation approaches in the OFDMA based multicellular networks with more emphasis on the frequency reused based ICI coordination schemes in the downlink systems. The geometry of the network severely affects the Signal to Interference and Noise Ratio (SINR); therefore, the wireless cellular systems are strongly dependent on the spatial BSs configuration and topology of a network. ICI mitigation techniques for both regular and irregular geometry networks are analyzed and a qualitative comparison along with the future research directions are presented.

Performance evaluation of inter-cell interference prediction in massive MIMO

This paper presents inter-cell interference prediction in massive multiple input multiple output. The rapid demand for widespread multimedia services notwithstanding the deployment of 4G in Lagos, Nigeria and the urgent need to upgrade to 5G networks with downlink and uplink data capacities of not less than 300 and 60 Mbps, respectively for at least 95% penetration rate at any instantaneous time; there is a possibility of experiencing crosstalk and adjacent inter-cell interference within the receiving antennas. 5G inter-cell interference prediction scheme that employs LTE performance index using locally sourced data from Huawei Nigeria limited was presented. The performances of the currently deployed LTE network were evaluated by employing performance metrics such as uplink and downlink capacities and recommending a possible inter-cell interference mitigation technique to be implemented in the deployment of 5G network in Lagos. The identified key performance metrics used include over the air emulation, carrier to interference plus noise ratio, peak RLC throughput, coverage probability, and the map-based model. Hence, ICIC static coordination algorithm, which comprise NOICIC, Hard FFR, PFR, SFR and SFFR were analyzed. With static ICIC algorithm, the coverage probability was 78% for receiving more than 20 kbps, with cell-edge users using resources of centre-users and with edge-users of neighbouring cells using different resource block; therefore reducing interference and consequently increasing throughput when there is static ICIC coordination. Implementing the static ICIC schemes on the 5G network when deployed in Lagos will improve the average downlink throughput over what is currently attainable with the 4G network in use at the moment

Dynamic and location‐based power allocation mechanism for inter‐cell interference mitigation in 5G heterogeneous cellular network

SummaryIn this paper, a dynamic and location‐based power allocation mechanism is proposed which could be adopted at both macrocell (MC) and overlaid fixed/mobile small cells (SCs) to mitigate inter‐cell interference (ICI) effects in heterogeneous cellular networks (HetCNs). The proposed Dynamic Power Allocation based on User Location (DPAUL) mechanism allows both MCs and deployed fixed/mobile SCs to dynamically allocate transmit power to its serving base stations (BSs) based on the location of a user in the cell. The paper illustrates the mitigation of dynamic downlink interferences occurring due to the mobility of SCs and users. The mobility of cell and its users is analyzed by introducing the Cell‐User mobility (CUM) model in the network. The proposed DPAUL mechanism is compared with the authors' other ICI mitigation techniques: Dynamic Fixed Region Cooperation (DFRC) and Dynamic Power Allocation Mechanism (DPAM). The network metrics Sumrate, User throughput, Energy‐efficiency, and Outage probability are investigated with allocation of sub 6 GHz and mmWave spectrums at MCs and fSCs/mSCs, respectively.

Dynamic and energy‐efficient ICI mitigation techniques for mobility‐based 5G HetCN

In this study, two dynamic mechanisms are proposed to mitigate inter-cell interference (ICI) in the heterogeneous cellular network (HetCN) namely: Dynamic Fixed Region Cooperation (DFRC) and Dynamic Power Allocation Mechanism (DPAM). The DFRC allows serving mSCs and other interfering base stations (BSs) to cooperate during transmission of a signal to a user. The DPAM dynamically allocates power to serving BS based on the farthest user in a cell. The study illustrates downlink interferences typically linked with a HetCN. For analysis, a macrocell (MC) network distributed with heterogeneous users is overlaid with both fixed and mobile small cells (SCs). The authors also introduced the cell-user mobility model for deployed mobile SCs in the network. The effects on network performance metrics: Sumrate, Average user throughput, and Energy efficiency are investigated with an allocation of sub 6 GHz and mmWave bands at MC and deployed SCs, respectively.

Successive Interference Cancellation and Fractional Frequency Reuse for LTE Uplink Communications

Cellular networks are increasingly densified to deal with the fast growing wireless traffic. Interference mitigation plays a key role for the dense cellular networks. Successive interference cancellation (SIC) and fractional frequency reuse (FFR) are two representative inter-cell interference (ICI) mitigation techniques. In this paper, we study the application of both SIC and FFR for LTE uplink networks, and develop an analytical model to investigate their interactions and impact on network performance. The performance gains with FFR and SIC are related to key system functionalities and variables, such as SIC parameters, FFR bandwidth partition, uplink power control and sector antennas. The ICIs from individual cell sectors are approximated by log-normal random variables, which enables low complexity computation of the aggregate ICI with FFR and SIC. Then, network performance of site throughput and outage probability is computed. The model is fast and has small modeling deviation, which is validated by simulations. Numerical results show that both SIC and FFR can largely improve network performance, but SIC has a stronger impact than FFR. In addition, most of the network performance gains with SIC could be obtained with a small number of SIC stages applied to a few sectors.

Comparative Analysis of Intercell Interference Mitigation Techniques in LTE-A Network

The performance of long term evolution-advance (LTE-A) depends on different factors such as spectral efficiency, throughput and signal interference to noise ratio (SINR). Interference causes the performance of a network to be grassed to very low level, it directly affects the parameters such as noise interference, receiving diversity and system receiving gain so to mitigate the interference in LTE-A network is very important. Interference occurs in two forms, intra-cell interference and inter-cell interference. Intra-cell interference is removed by orthogonal frequency division multiple access, but the problem of inter-cell interference still exists due to reception of signals from two adjacent base stations at same frequency on user equipment, so coordination is applied between the cells to reduce the interference between the cells. This paper focuses on coordination between the base stations using dynamic cooperative Base Station selection (DCBS). In this paper, SINR, system capacity, minimum and maximum rates of the system are analyzed when coordination is applied between the cells. Three different scenarios are discussed in this paper, which includes coordinated multipoint transmission and reception (COMP), non-COMP and DCBS and then the results of these scenarios are compared.

Improvements of femto‐base station resource utilisation and ABS assignment convergence for dynamic ABS assignment

Almost blank subframe (ABS) techniques emerge as inter-cell interference mitigation techniques in time region. One of the conventional ABS techniques is dynamic ABS assignment, which is able to adapt to interference state to protect the outage users more. However, the number of ABS assignments increases to protect a lot of outage users in the dense BS deployment. Therefore, the resource utilisation of base stations (BSs) decreases. Moreover, the convergence time of subframe assignment should be short enough to adapt to the change of environments. In this study, the authors propose a dynamic ABS assignment method to improve the resource utilisation of BSs and the convergence time of subframe assignment. Each BS receives feedback from surrounding BSs and users, and selects its subframe assignment based on the received feedback. Simulation results show that the proposed method improves the resource utilisation of BSs and the convergence time of subframe assignment compared with the conventional dynamic ABS assignment one, while achieving a similar user outage ratio.

Non-Orthogonal Multiple Access for Large-Scale 5G Networks: Interference Aware Design

Non-orthogonal multiple access (NOMA) is promoted as a key component of 5G cellular networks. As the name implies, NOMA operation introduces intracell interference (i.e., interference arising within the cell) to the cellular operation. The intracell interference is managed by careful NOMA design (e.g., user clustering and resource allocation) along with successive interference cancellation. However, most of the proposed NOMA designs are agnostic to intercell interference (i.e., interference from outside the cell), which is a major performance limiting parameter in 5G networks. This paper sheds light on the drastic negative-impact of intercell interference on the NOMA performance and advocates interference-aware NOMA design that jointly accounts for both intracell and intercell interference. To this end, a case study for fair NOMA operation is presented and intercell interference mitigation techniques for NOMA networks are discussed. This paper also investigates the potential of integrating NOMA with two important 5G transmission schemes, namely, full duplex and device-to-device communication. This is important since the ambitious performance defined by the third generation partnership project for 5G is foreseen to be realized via seamless integration of several new technologies and transmission techniques.

Inter-Cell Interference Mitigation Techniques in Long Term Evolution Networks: A Survey

Objectives: This paper gives survey of different techniques and the overview of how the bandwidth is dispensed to the users at the major/edge regions and minor/center regions .It also gives an overview of how the power is dispensed to the users at minor group and major group regions Methods: ICIC has one of the schemes which is based on reusing the frequency called as Fractional Frequency Reuse (FFR). There are different techniques of FFR. They are Partial Frequency Reuse (PFR), Soft Frequency Reuse (SFR) and Soft Fractional Frequency Reuse (SFFR). Findings: In this survey it is found that, the different techniques of FFR gives different throughput and it is also found that SFFR scheme gives the highest throughput when compared with others. Applications: The different techniques of FFR can be used in LTE (Long Term Evolution) based networks. The users will get benefitted based on different power allocations. The real time applications of this technique can be seen in 4G networks.

5G Backhaul Challenges and Emerging Research Directions: A Survey

5G is the next cellular generation and is expected to quench the growing thirst for taxing data rates and to enable the Internet of Things. Focused research and standardization work have been addressing the corresponding challenges from the radio perspective while employing advanced features, such as network densification, massive multiple-input-multiple-output antennae, coordinated multi-point processing, inter-cell interference mitigation techniques, carrier aggregation, and new spectrum exploration. Nevertheless, a new bottleneck has emerged: the backhaul. The ultra-dense and heavy traffic cells should be connected to the core network through the backhaul, often with extreme requirements in terms of capacity, latency, availability, energy, and cost efficiency. This pioneering survey explains the 5G backhaul paradigm, presents a critical analysis of legacy, cutting-edge solutions, and new trends in backhauling, and proposes a novel consolidated 5G backhaul framework. A new joint radio access and backhaul perspective is proposed for the evaluation of backhaul technologies which reinforces the belief that no single solution can solve the holistic 5G backhaul problem. This paper also reveals hidden advantages and shortcomings of backhaul solutions, which are not evident when backhaul technologies are inspected as an independent part of the 5G network. This survey is key in identifying essential catalysts that are believed to jointly pave the way to solving the beyond-2020 backhauling challenge. Lessons learned, unsolved challenges, and a new consolidated 5G backhaul vision are thus presented.

Multi-Cell Coordinated Scheduling and MIMO in LTE

This paper provides an overview of multi-cell coordinated scheduling and multiple-input multiple-output (MIMO) techniques in LTE. We first discuss single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO) for LTE and identify potential techniques for further improving the performance of LTE, such as enhanced channel state information feedback and adaptive switching between SU-MIMO and MU-MIMO. Then, we address inter-cell interference mitigation techniques for downlink and uplink, respectively. Finally, potential research challenges and topics in the area are discussed.

Selecting the Optimal Fractional Frequency Reuse Scheme in Long Term Evolution Networks

Long Term Evolution (LTE) networks offer high capacity and are specified and designed to accommodate small, high performance, power-efficient end-user devices. One limiting factor that influences LTE performance is the interference from neighbouring cells, the so called Inter-Cell Interference (ICI). The investigation of ICI mitigation techniques has become a key focus area in achieving dense spectrum reuse in next generation cellular systems. Fractional Frequency Reuse (FFR) has been proposed as a technique to overcome this problem, since it can efficiently utilize the available frequency spectrum. This manuscript proposes a dynamic mechanism that selects the optimal FFR scheme based on a custom metric, which is called user satisfaction. In detail, the proposed mechanism divides the cell into two regions, the inner and outer region, and selects the optimal size as well as the optimal frequency allocation between these regions with main target to maximize the user satisfaction metric. The proposed mechanism is evaluated through several simulation scenarios that incorporate users' mobility and its selected FFR scheme is compared with other frequency reuse schemes in order to highlight its performance.

Joint User Scheduling and Adaptive Intercell Interference Cancelation for MISO Downlink Cellular Systems

Recently, an adaptive intercell interference (ICI) mitigation technique has been proposed for downlink cellular systems as a means to increase throughput with low system complexity. However, in the prior work, the issue of intercell user scheduling has not been considered. In this paper, we study multiple-input-single-output (MISO) downlink cellular systems that jointly design adaptive ICI cancelation (ICIC) and intercell user scheduling assuming that partial channel state information (CSI) is shared among base stations (BSs). Since the optimal solution would require high complexity, we investigate a new low-complexity algorithm that selects the best users and their beamforming strategies in terms of maximizing the weighted sum rate (WSR). To this end, we first develop a simple threshold criterion for each user to decide the preferred beamforming strategy based on the derivation of the expected signal-to-interference-plus-noise ratio (SINR). Then, according to users' feedback about their decisions, a successive user and beamforming selection algorithm is performed at the BSs. From simulation results, we show that, combined with proportional fair scheduling, the proposed scheme provides excellent throughput performance with very low computational complexity and the amount of inter-BS CSI exchange. Furthermore, we discuss an extension of the proposed scheme to limited feedback systems and observe that our algorithm also provides similar advantages over conventional schemes with quantized feedback.

Short-Term Multi-Cell Dynamic Resource Allocation in Future Cellular Networks

In future cellular system, it is becoming more challenging to optimize the radio resource management and maximize the system capacity whilst meeting the required quality of service from user's point of view. Traditional schemes have approached this problem mainly focusing on resources within a cell and to large extent ignoring effects of multi-cell architecture. For multi-cell systems employing intra-cell orthogonal communication channels, inter-cell interference mitigation techniques are expected to be one of the key radio resource management functions. In this paper, we propose a multi-cell coordinated and un-coordinated dynamic resource sharing algorithms and reuse techniques among base station/ relay station cells. The sub carrier allocation and power allocation are performed on the basic of sum-rate maximization, by considering the load over the cell (3-sector cell). The simulation results show the performance comparison between both coordinated and un-coordinated resource allocation schemes with different sum-rate maximization algorithms.

On Collision Probabilities in Frequency-Domain Scheduling for LTE Cellular Networks

In an Orthogonal Frequency Division Multiple Access (OFDMA) wireless network, inter-cell interference (ICI) is one of the main challenges, and is of special concern for users near the cell edge. ICI arises naturally from collisions of frequency resource assignments among neighboring base stations. An important performance parameter is the probability distribution of assignment collisions. In this paper, an exact analytical expression for the collision probability is derived for an arbitrary number of base stations with non-coordinated schedulers. The expression can be used to determine conditions under which ICI mitigation techniques may be required as well as to establish a baseline for performance comparison with ICI coordination schemes. For the important case of two base stations, the expression is particularly simple. Numerical results are presented to illustrate the analytical results.

Research on uplink coordinated transmission schemes in LTE-advanced systems

The investigation of inter-cell interference mitigation techniques is a key area in wireless communications. Coordinated multiple points (CoMP) transmission/reception is a candidate technique for interference cancellation in 3GPP LTE-Advanced system. However, the coordination scheme in CoMP remains a key research problem to be solved, which will have a strong influence on the performance of CoMP. In this paper, a novel coordinated transmission scheme is proposed for the uplink LTE-Advanced system. In our scheme, several base transceiver stations (BTS) and users are selected as coordination partners which form a CoMP cluster. Joint processing is used at the receiver to mitigate interference. From the perspective of coordinated partner selection, our scheme can be divided into static and dynamic coordination which are both considered to fully exploit the throughput gain of CoMP. The proposed schemes are evaluated by system level simulation and compared with the conventional LTE system based upon single cell processing. Our simulation results demonstrate that the proposed schemes attain superior performance as opposed to the conventional system in terms of cell average and cell edge throughput.