Dynamic Resource Partitioning for Downlink Femto-to-Macro-Cell Interference Avoidance (original) (raw)
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Femto-Cell Resource Partitioning
2009 IEEE Globecom Workshops, 2009
This paper studies the impact of femto-cell underlay deployment that share radio frequency resources with urban macro-cells. Femto-cells promise substantial gains in spectral efficiency due to an enhanced reuse of radio resources. However, owing to their random and uncoordinated deployment, femtocells potentially cause destructive interference to macro-cells and vice versa. In order to maintain reliable service of macro-cells, it is most important to mitigate destructive femto to macro-cell interference. In the downlink, this can be achieved by dynamic resource partitioning, in the way that femto base stations (BS) are denied access to resources that are assigned to close by macro mobile stations (MS). By doing so, interference to the macro-cells is effectively controlled, at the expense of a modest degradation in femto-cell capacity. The necessary signalling is conveyed through the wired backbone, using a high interference indicator (HII).
Bulletin of Electrical Engineering and Informatics, 2019
The Femto-Macro heterogeneous network is a promising solution to improve the network capacity and coverage in mobile network. However interference may rise due to femtocell deployment nearby to macro user equipment (MUE) within macrocell network coverage. Femtocell offers main priority in resource allocation to its subscribed femto user equipment (FUE) rather than unsubscribed MUE. MUEs will suffer severe interference when they are placed near or within the femtocell area range especially at the cell edge. This phenomenon occurs due to the distance is far from its serving macro base station (MBS) to receive good signal strength. This paper presents a design of cell selection scheme for cell-edge MUE to select an optimal femto base station (FBS) as its primary serving cell in physical resource block allocation. In this study, the proposed cell selection consists of four main elements: measuring the closest FBS distance, Signal to Interference-plus- Noise-Ratio (SINR), physical resour...
Scalable and Self-Sustained Algorithms for Femtocell Interference Mitigation
Cellular networks are reaching their physical limits providing capacity that is almost near the Shannon theory. However, cellular usage is still increasing exponentially with hungry applications demanding higher data rates. As a result, designers are facing significant challenge in meeting the required demands. One of the promising solutions, being fostered by the 3GPP, is to increase the spectral efficiency through higher frequency reuse using smaller and denser network cells such as femto, pico and nano cells. One of the main challenges behind using smaller cells is managing interference, in this paper, we propose two novel solutions that alleviate the interference of femto-cells on macro-cell user equipment (MUEs). The solutions do not rely on any additional information exchange or signaling, nor do they rely on the backhaul and it's delay. The first proposal is Femto-cell Power Control Scheme (FPCS) that utilizes an analytical approach to adapt the femto base station's transmit power based on Channel Quality Indicator (CQI) reports from affected MUEs. The second method is Random Physical Resource Block Selection Scheme (RPSS) that allocates the femto-cell's resources from a random subset of Physical Resource Blocks (PRBs) so that the MUEs benefit from a reduced interference level. Our evaluations have shown that the two proposals do alleviate the femto-cell interference significantly, increasing the SINR and enhancing the end performance. To the best of our knowledge, no similar work exist in literature that addresses the femto-cell's interference without information exchange.
International Journal of Computer Applications, 2017
The deployment of small cell node such as femto-cell within macro area coverage has been considered a promising solution to provide better throughput and Quality of Experience (QoE) to users. However, co-channel deployment of femto-cell operating in a closed access mode (CSG) causes severe cross-tier interference. In this paper we have develop an adaptive Hybrid Power control and Time domain Technique (aHPTT) to mitigate cross-tier interference in HetNet. The hybrid technique was developed to handle limitations associated with using a single interference mitigation technique such as Power Control (PC) and Time Domain (TD). aHPTT integrate PC and TD to mitigate interference simultaneously depending on the position of the user in the network. The hybrid technique was implemented in a Graphical User Interface (GUI) using MATLAB R2013a. System level simulation was carried out to evaluate the performance of the hybrid technique in terms of user's throughput. The aHPTT was validated with the 3rd Generation Partnership Project (3GPP) enhance Inter-cell Interference Coordination (eICIC) technique, results obtained showed that the aHPTT performs better than PC technique by 2.90% and TD technique by 82.60%.
Adaptive interference mitigation techniques for femtocells
… (WCNC), 2012 IEEE, 2012
1 Heterogeneous Networks (HetNets) comprising of Macro and Femto stations are very promising to increase indoor coverage and throughput of the future cellular networks. In this paper, we characterize the interference environment of the Femto HetNets based on the Femto dual strip deployment model. We show that the Macro Indoor subscribers or User Equipments (UEs), who are not associated with Femto stations (FSs), are the victim UEs. Motivated by this performance degradation, we propose three interference mitigation (IM) techniques. The first technique turns off the interfering FSs in some of the available time-frequency resource blocks (RBs) to free these RBs to be utilized by the Macro UEs. The second technique applies adaptive multi-user zero-forcing (A-MUZF) scheme causing zero interference to the Macro Indoor UEs. The third scheme applies power control in addition to either A-ICIC or A-MUZF. Via Extensive system level simulations (SLS), we show that the proposed schemes significantly improve the performance of the Macro Indoor UEs, while maintaining the high throughput achieved by the FSs.
Radial Sub-band Allocation with Downlink Interference Mitigation in Macro–Femto Environment
Wireless Personal Communications, 2019
Femtocell deployment is an important strategy when it comes to improvement of QoS metrics in areas of poor cell coverage like indoors in an LTE environment. This, however, is accompanied by bottlenecks in resource allocation and trade-offs in accuracy for interference management in the heterogeneous two-tier network of macro and femtocell environment. To that end, we propose two schemes using radial division of cells that allocate sub-bands to both femtocell users and macrocell users which in turn, mitigates co-channel interference. Simulation results show that our proposed schemes, commonly named as radial sub-band allocation (RSA-1 and RSA-2) improve performance as measured by signal to interference and noise ratio, sum throughput, outage probability, and channel reuse efficiency while maintaining a balance in computational complexity with existing schemes like F-ALOHA. Further experimentation revealed that the proposed version also works exceedingly well in ultra-dense environments.
Co-tier downlink interference management in dense femtocell networks
International Journal of Communication Systems, 2016
With the adoption of long-term evolution standard for 4G mobile communications, the deployment of femtocell base stations (FBSs) to cope with the surging traffic in mobile wireless communication is becoming increasingly popular. However, with the random installation of FBSs, the problem of interference among FBSs is still a challenge. In this paper, assuming the presence of a femtocell management system that can control and coordinate the densely deployed FBSs, a novel power backoff scheme is proposed that determines the appropriate transmit power of each FBS so that the interference is reduced. Simulation results for randomly deployed FBSs in an environment with shadowing using MATLAB are provided, showing that our proposed methods can effectively mitigate the co-tier downlink interference while improving the system capacity in a densely deployed femtocell network with shared spectrum use. Quantitatively, the average interference is reduced by roughly 90% to 100% of dBm, and the average capacity is increased by more than 80%. These results attest to the effectiveness of the proposed scheme.
Macrocell Resource Adaptation for Improved Femtocell Deployment and Interference Management
2013
This paper studies the spectrum sharing of femtocell base station (FBS) and macrocell base station (MBS) in a heterogeneous network setting. We allow femtocell users (FUEs) to re-use the resource blocks of certain macrocell users (MUEs) who are categorized as outdoor users. We study the design tradeoff between MUE spectral diversity and the need to accommodate femtocells by intelligently determining when an MUE should be allowed to change resource allocation. Modeling the wireless channel state as a Markov chain, we formulate the decision as a Markov decision process (MDP). In the case of homogeneous channels environment, we reduce the MDP complexity, which enables the MBS to form the optimal decision matrix by solving only two equations. Our closed form expressions reveal the quantitative relationship among system parameters. Hence, we obtain an easy policy for the optimal channel switching. Our scheme is also robust to the uncertainties in the Markov models.
On Providing Downlink Services in Collocated Spectrum-Sharing Macro and Femto Networks
IEEE Transactions on Wireless Communications, 2000
Femtocells have been considered by the wireless industry as a cost-effective solution not only to improve indoor service providing, but also to unload traffic from already overburdened macro networks. Due to spectrum availability and network infrastructure considerations, a macro network may have to share spectrum with overlaid femtocells. In spectrum-sharing macro and femto networks, inter-cell interference caused by different transmission powers of macrocell base stations (MBS) and femtocell access points (FAP), in conjunction with potentially densely deployed femtocells, may create dead spots where reliable services cannot be guaranteed to either macro or femto users. In this paper, based on a thorough analysis of downlink (DL) outage probabilities (OP) of collocated spectrum-sharing orthogonal frequency division multiple access (OFDMA) based macro and femto networks, we devise a decentralized strategy for an FAP to self-regulate its transmission power level and usage of radio resources depending on its distance from the closest MBS. Simulation results show that the derived closedform lower bounds of DL OPs are tight, and the proposed decentralized femtocell self-regulation strategy is able to guarantee reliable DL services in targeted macro and femto service areas while providing superior spatial reuse, for even a large number of spectrum-sharing femtocells deployed per cell site.
Femto-macro cellular interference control with subband scheduling and interference cancelation
2010
Abstract A significant technical challenge in deploying fem-tocells is controlling the interference from the underlay of femtos onto the overlay of macros. This paper presents a novel interference control method where the macrocell bandwidth is partitioned into subbands, and the short-range femtocell links adaptively allocate their power across the subbands based on a load-spillage power control method.