To further improve spectral efficiency for current wireless communication systems, we propose a new lazy learning-based cancellation approach to suppress self-interference (SI) sent from a base station and enable in-band full-duplex (IBFD) transmissions in cellular networks. Differ from the existing IBFD systems based on traditional approaches, our proposal consists of two phases: an offline phase for database generation and an online phase for data transmission. In the offline phase, the output before a 0/1 decision is previously measured without the desired signal input and recorded to a database with self-defined feature vectors (FVs). In the online phase, for the same system architecture with the desired signal input, a suitable result is sought from the generated database with the help of a learning method and the use of FV; then, the result is assigned as a value of SI cancellation. Computer simulation results indicate that the proposed cancellation approaches can achieve about 134 dB SI suppression and thus enables the IBFD transmissions in the considered systems.

In this paper, we conceive an advanced small cells wireless network deployment framework within a managed space under shared spectrum access paradigm. We also conceive a complementary business model, referred to as neutral host micro operator (NH-μO), that leverages a single shared wireless infrastructure to mutually benefit μO (a third party service provider), the owner of the space/facility, and mobile network operators (MNOs). The model is composed of a μO slice, which delivers a venue with customized wireless services tailored to the its local service requirements, and an MNO slice, which facilitates improved wireless coverage to visitors/end-users with subscriptions to several different MNOs. The NH-μO is not biased to favor any specific client, which can be enforced through a concrete commercial agreement. A radio access network slicing concept is exploited to support and optimize both the slice instances (SIs) efficiently in a shared manner on a single physical network infrastructure. In addition, we devise an efficient architecture for the NH-μO small cell base station and dynamic spectrum assignment control unit, and their required functionalities supporting sustainable coexistence of different SIs in shared spectrum. We also devise both interSI and intra-SI dynamic spectrum allocation policies considering time-varying requirements of different SIs. These policies take care of application level priority by providing a proper mixture of users with guaranteed quality of service and best-effort users, while ensuring a healthy SI competition. The advantages of the proposed framework are twofold. It enables the venue owner to manage its wireless networks and consider its very specific requirements while capitalizing from the MNO slice. This, in turn, reduces the need for deployment of new infrastructure while providing improved wireless coverage and savings to MNOs. Finally, our proposed framework leverages efficient utilization of spectrum, physical infrastructure, and computational resources. The simulation results exhibit various important features of the proposed shared spectrum access policies.

With the increasing demand of wireless multimedia services, the multimedia broadcast multicast service (MBMS) is an emerging technology which is adopted in new wireless communication standards to enhance multimedia data transmission. In an MBMS system, all the users subscribing to the service receive multimedia data via the broadcast channel from the base station (BS). To ensure the quality of the broadcast, the MBMS users feedback their channel state information (CSI) to the BS. The BS then selects the best transmission mode according to the users' feedbacks to achieve the optimal result. This CSI feedback operation results in increasing feedback load with the number of users and hence reduces the spectrum efficiency. In this paper, a novel method is proposed to reduce the feedback load of the MBMS systems. The proposed method let the users determine individually whether feeding back their CSI will be critical for the BS to select the transmission mode. If not, a user does not feedback. Different decision rules at the users incur different degrees of MBMS rate loss, which is mathematically analyzed. Through simulations, we show that the proposed method can significantly reduce the CSI feedback load with only a slight impact on the MBMS rate.

This paper studies cooperative beamforming in multihop amplify-and-forward relay networks. We adopt a layer-by-layer approach, namely per-layer sum-rate maximization, to compute the beamforming weights employed by the relays at each layer. When there is only one receiving node at the adjacent downstream layer, the per-layer sum-rate maximization problem is equivalently converted into a convex quadratically constrained quadratic program. When there are multiple receiving nodes at the adjacent downstream layer, the per-layer sum-rate maximization problem is nonconvex and is equivalently transformed into a difference-of-convex (DC) program. We develop a successive convex approximation algorithm to approximately solve this DC program. Numerical results confirm that the proposed beam-forming design outperforms the existing ones in the literature in terms of achievable data rate, and the proposed scheme is effective for suppressing noise propagation.

Traditional Orthogonal frequency-division multiplexing channel realization methods need transformations of transmission symbols between time and frequency domains and therefore result in quite a high computational complexity. In this paper, a channel realization method only in the frequency domain is proposed to reduce the complexity of simulation. An example following the IEEE 802.16m standard is also given to illustrate the advantage of the proposed method. The results show that the proposed method indeed well and stably approximates the OFDM channel in the IEEE 802.16m environment.