Poor cell selection is the main challenge in Picocell (PeNB) deployment in Long Term Evolution- (LTE-) Advanced heterogeneous networks (HetNets) because it results in load imbalance and intercell interference. A selection technique based on cell range extension (CRE) has been proposed for LTE-Advanced HetNets to extend the coverage of PeNBs for load balancing. However, poor CRE bias setting in cell selection inhibits the attainment of desired cell splitting gains. By contrast, a cell selection technique based on adaptive bias is a more effective solution to traffic load balancing in terms of increasing data rate compared with static bias-based approaches. This paper reviews the use of adaptive cell selection in LTE-Advanced HetNets by highlighting the importance of cell load estimation. The general performances of different techniques for adaptive CRE-based cell selection are compared. Results reveal that the adaptive CRE bias of the resource block utilization ratio (RBUR) technique exhibits the highest cell-edge throughput. Moreover, more accurate cell load estimation is obtained in the extended RBUR adaptive CRE bias technique through constant bit rate (CBR) traffic, which further improved load balancing as against the estimation based on the number of user equipment (UE). Finally, this paper presents suggestions for future research directions.

Summary LTE‐Advanced heterogeneous networks deployment is meant to address the increasing demand for quality of service, high data rates and coverage extension. Load balancing is among the primary challenges, especially when the user equipments (UEs) associate with diverse transmission power network tiers using received signal strength. The low‐power network tier's spectrum will be underutilized, and UEs associated with them will be inflicted by interference from the high‐power network tier. The proposed hybrid channel gain prioritized access (HCGPA)‐aware cell association scheme stresses the importance of combined metrics with interference mitigation to simultaneously achieve load balancing and enhance performance among the network tiers. The high‐priority UEs associate with the tier that gives the maximum channel gain being higher than a given threshold. While the low‐priority UEs association is based on the maximum joint metrics (channel gain, channel access probabilities of low‐priority UEs and high‐priority UEs). The HCGPA scheme has 1.72 times the number of UEs connected to low‐power networks, 8% better load balancing fairness, compared with the conventional reference signal receive power and RSRP + 6 dB bias cell associations. Although the susceptibility of HCGPA to interference led to the poor signal to interference to noise ratio (SINR) performance of the cell‐edge UEs, the cell‐centre UEs exhibited the best spectral efficiency performance. Copyright © 2016 John Wiley & Sons, Ltd.

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User equipments (UEs) offloaded from the MeNBs to the PeNBs via cell range extension (CRE) bias in a co-channel deployment suffered severe interference. The severity of the downlink interference varies significantly with the change in the CRE bias. The baseline approach for Interference mitigation technique based on time domain muting (TDM) of resources by MeNBs used trial and error technique which is causing resource wastage and is practically not feasible. Proposed here is a Model for TDM based on estimated cell load conditions and symbol efficiency (SE) as metrics to determine the muting ratio of resources. System level simulation was conducted to validate the throughput performances and the MeNBs-PeNBs resource trade-offs of the proposed method. Compared to the baseline (centralized) approach, the proposed decentralized TDM algorithm exhibited optimal throughput performance and adapted to the change in CRE bias with better trade-offs.

This paper aims at the development of floating gate MOSFET (FGMOS) based low voltage (+ 0.75 V), voltage-mode and current-mode circuits. Using low voltage CCII, impedance converter has been realized, which is used to simulate high value of inductance for at least 100 kHz. This circuit has also been used as capacitance multiplier. Some new bandpass filter circuits have also been presented. The circuits employ FGMOS based active elements besides grounded capacitors and are suitable for chip implementation. Theoretical results have been validated by PSpice simulations carried out using 0.5 gm CMOS technology parameters.