17 research outputs found
Interference Cancellation and Suppression in Asynchronous Cooperating Base Station Systems
Abstract-We consider cooperating base station systems where the users are not aligned in time and frequency to the core network as it is actually desired for coherent joint signal processing. As it is widely known, time and frequency offsets can cause intersymbol as well as inter-carrier interference in OFDM systems which leads to a reduced transmission performance. In this paper we investigate uplink joint detection algorithms which, in addition to multi-user interference cancellation, reduce the asynchronous interference by using iterative interference cancellation as well as mitigating the additional interference by exploiting spatial diversity. The structure of the asynchronous interference in frequency domain can be exploited to derive algorithms with scalable complexity. As will be seen, particularly the interference suppression algorithm provides very good performance results with only a moderate complexity increase
Implementation of the 3GPP LTE-WLAN Interworking Protocols in NS-3
The next generation wireless standard, called Fifth Generation (5G), is being
designed to encompass Heterogeneous Networks (HetNets) architectures consisting
of a single holistic network with Multiple Radio Access Technologies
(Multi-RAT). Multiple connectivity protocols and spectrum would be managed from
a common core (management system) handling both: i) traditional macro cellular
systems (such as LTE), that can provide long-range, outdoor coverage, as well
as ii) low-power wireless systems with high capacity (such as Wi-Fi), that can
be deployed to cater indoor traffic needs. 5G HetNets are expected to achieve
ubiquitous connectivity that would guarantee Quality of Service (QoS), Quality
of Experience (QoE) along with efficient use of spectrum and energy at low
cost. Tightly coupled LTE-Wi-Fi networks have emerged as one of the promising
solutions in the 5G era to boost network capacity and improve end user's
quality of experience. LTE/Wi-Fi Link Aggregation (LWA) and LTE WLAN Radio
Level Integration with IPSec Tunnel (LWIP) are two approaches put forward by
the 3rd Generation Partnership Project (3GPP) to enable flexible, general, and
scalable LTE-WLAN inter-working. These techniques enable operator-controlled
access of licensed and unlicensed spectrum and allow transparent access of
operator's evolved core. The most important aspect of these techniques is that
they could be enabled with straightforward software upgrades and can utilize
the already existing Wi-Fi networks. This article presents and motivates the
design details of LWA and LWIP protocols. We also present the first NS-3 LWA
and LWIP implementations over Network Simulator 3 (NS-3). In particular, this
work focuses on the adaptation and concurrent usage of different NS-3 modules
and protocols of different technologies to enable the support of these
interworking schemes