LTE-A femto-cell interference mitigation with MuSiC DOA estimation and null steering in an actual indoor environment

Abstract

This paper deals with a cognitive approach used to reduce the co-channel interference arising from the coexistence of an LTE macrocell and an LTE femtocell sharing the same frequency band. Multiple-antennas technology is considered to exploit the angle dimension as a new spectrum opportunity: femtocell acts as a secondary system and inserts nulls in the directions of the UE connected to the macrocell thus protecting the downlink transmission of the primary base station. MuSiC algorithm is used to detect the DOA of the UE signal replicas in an indoor environment assuming a variable number of multipath components characterized by a very large angle spread. The proposed scheme permits to increase the signal to interference ratio at the UE side thus reducing the achieved error rate on the downlink connection even when the number of resolvable paths is higher than the number of antennas. Finally the UE mobility is considered to take into account the effect of variable DOAs.

Cognitive Spectrum Sharing: An Enabling Wireless Communication Technology for a Wide Use of Smart Systems

“…However, the knowledge of DoA of multiple signals can be challenging in multipath propagation channels and strongly depends on the number of antenna elements used at the receiving end. In [58], a method is proposed for CHetNets based on DoA estimation and zero forcing beamforming that focuses on problems that arise in actual propagation channels. This method can be applied either in UL or DL, assuming a correlated spatial information among the two links.…”

Reliable Adaptive Resource Management for Cognitive Cloud Vehicular Networks

“…Each super-frame comprises an uplink phase and a downlink phase. Since the broadcast bandwidth from the serving RSU to the served VCs is typically larger than the access bandwidth from the served VCs to the serving RSU [13] and several works afforded the corresponding scheduling/transmission aspects [3], [14], [15], [16], [17], [18], [19], [20], [21], [22] in this paper, we focus on the downlink phase of each super-frame and consider the related packets collision phenomena possibly occurring at the serving RSUs. Specifically, during the downlink phase, RSU (i) utilizes the carrier frequency f i+1 and its port-2 to relay the backbone traffic to RSU (i + 1), and exploits the carrier frequency f i for simultaneously receiving the backbone traffic generated by RSU (i−1) and the access traffic offloaded by the currently served VCs (see the arrowed rays of Fig.…”

“…PROPOSITION 1. Under the above reported assumptions, the NOP in (20), (21) can be equivalently recast into I parallel and independent sub-problems over the RSU index i ∈ I. Specifically, at slot t ≥ T , the i-th RSU autonomously solves the i-th Combined Time-Flow Allocation Problem (e.g., the i-th CTFAP), which is formally defined as:…”

Green multimedia wireless sensor networks: distributed intelligent data fusion, in-network processing, and optimized resource management

“…In general, the use of small cells leads to enhancement of the delivered service quality with increased offered capacity and coverage [12]. But small cells can also be used to reduce the power in transmission (i.e., green communications).…”