Breast cancer remains a leading cause of mortality among women, with millions of new cases diagnosed annually. Early detection through screening is crucial. Using neural networks to improve the accuracy of breast cancer screening has become increasingly important. In accordance with radiologists' practices, we proposed using images from the unaffected side to create adversarial samples with critical medical implications in our adversarial learning process. By introducing beneficial perturbations, this method aims to reduce overconfidence and improve the precision and robustness of breast cancer classification. Our proposed framework is an adversarial quadruple-view classification network (NaFV-Net) incorporating images from both affected and unaffected perspectives. By comprehensively capturing local and global information and implementing adversarial learning from four mammography views, this framework allows for the fusion of features and the integration of medical principles and radiologist evaluation techniques, thus facilitating the accurate identification and characterization of breast tissues. Extensive experiments have shown the high effectiveness of our model in accurately distinguishing between benign and malignant findings, demonstrating state-of-the-art classification performance on both internal and public datasets.

In this paper, we develop a framework for user association in infrastructure-based wireless networks, specifically focused on flow-level cell load balancing under spatially inhomogeneous traffic distributions. Our work encompasses several different user association policies: rate-optimal, throughput-optimal, delay-optimal, and load-equalizing, which we collectively denote α-optimal user association. We prove that the optimal load vector ρ*that minimizes a generalized system performance function is the fixed point of a certain mapping. Based on this mapping, we propose and analyze an iterative distributed user association policy that adapts to spatial traffic loads and converges to a globally optimal allocation. We then address admission control policies for the case where the system is overloaded. For an appropriate system-level cost function, the optimal admission control policy blocks all flows at cells edges. However, providing a minimum level of connectivity to all spatial locations might be desirable. To this end, a location-dependent random blocking and user association policy are proposed.

Relay is one of the key features being considered for IMT-Advanced systems. The relay architectures defined in IEEE 802.16m and 3GPP LTE-Advanced are optimized only for non-mobile relay, i.e., the Relay Station is attached to a designated Base Station and becomes a part of the fixed access network. A mobile relay architecture, where relay may switch attached BS according to operation demand, will promise more resilient relay deployment. In this paper, we first highlight three use cases where mobile relays can offer useful deployment options. Next, we propose an enhanced handover mechanism for relay-based group mobility by extending the IEEE 802.16m specification on relay. To this end, we describe the handover architecture for mobile relay highlighting the C-plane and U-plane enhancements required in order to support group mobility of mobile stations. Using illustration and comparisons, we show that mobile relay will offer significant benefits of signaling overhead reduction and provide users seamless mobility experience compared to fixed relays.

In this study, the authors consider the benefits of mobile terminals (MTs) with different access points (APs) for uplink and downlink transmission to conserve MTs’ energy. In traditional cellular networks, an MT is typically associated with a single AP. However, as wireless networks evolve, heterogeneous and/or overlay deployment scenario become viable and an MT can be associated with different APs for uplink and downlink transmission. The authors call this ‘dual APs association’. The authors show that allowing dual APs association provides a significant gain on the uplink system capacity and/or the uplink transmit power savings. As a specific example of the use of dual APs, the authors focus on relay networks and show that considering the relay cost further increases the benefits of this approach. Based on extensive simulations using IEEE 802.16m relay network Evaluation Methodology, the authors demonstrate that dual APs can improve the uplink harmonic capacity by 350% or reduce the uplink transmit power by 7 dB. The authors note, however, that there exists a signalling cost in implementing dual APs association, which needs be overcome to achieve these substantial performance improvements.

In this paper we develop a framework for user association in infrastructure-based wireless networks, specifically focused on flow-level cell load balancing under spatially inhomogeneous traffic distributions. Our work encompasses several different user association policies: rate-optimal, throughput- optimal, delay-optimal, and load-equalizing, which we collectively denote α-optimal user association. We prove that the optimal load vector ρ∗ that minimizes a generalized system performance function is the fixed point of a certain mapping. Based on this mapping we propose and analyze an iterative distributed user association policy that adapts to spatial traffic loads and converges to a globally optimal allocation.

WiMAX technology, based on IEEE 802.16 standard, is a promising broadband wireless technology for future 4G network. WiMAX provides radio access with centralized control, where bandwidth resources are managed and allocated by base station (BS) for both uplink (UL) and downlink (DL). Current WiMAX standard defines several bandwidth request (BWReq) mechanisms to serve a variety of applications, which however may not be efficient for on-off bursty traffic patterns. In this paper, we propose a novel adaptive polling service (aPS), with the advantage of significantly reducing the signaling overhead associated with the bandwidth request process without compromising the delay performance of real-time applications. Extensive simulations demonstrate that aPS outperforms existing scheduling services in terms of overall efficiency for a wide range of applications.

The transmission capacity (TC) of a wirelessad hocnetwork is defined as the maximum spatial intensity of successful transmissions such that the outage probability does not exceed some specified threshold. This work studies the improvement in TC obtainable with successive interference cancellation (SIC), an important receiver technique that has been shown to achieve the capacity of several classes of multiuser channels, but has not been carefully evaluated in the context ofad hocwireless networks. This paper develops closed-form upper bounds and easily computable lower bounds for the TC ofad hocnetworks with SIC receivers, for both perfect and imperfect SIC. The analysis applies to any multiuser receiver that cancels the$K$strongest interfering signals by a factor$z \in [0,1]$. In addition to providing the first closed-form capacity results for SIC inad hocnetworks, design-relevant insights are made possible. In particular, it is shown that SIC should be used with direct sequence spread spectrum. Also, any imperfections in the interference cancellation rapidly degrade its usefulness. More encouragingly, only a few—often just one—interfering nodes need to be canceled in order to get the vast majority of the available performance gain.

This paper proposes a new principle for designing MAC protocols for spread spectrum based ad hoc networks -- inducing spatial clustering in contending transmitters/receivers. We first highlight the advantages of spread spectrum in handling quality of service (QoS) requirements, enhancing energy efficiency, and enabling spatial multiplexing of bursty traffic. Then, based on stochastic geometric models and simulation, we show how idealized contention resolution among randomly distributed nodes results in clustering of successful transmitters and receivers, in turn leading to efficient spatial reuse. This motivates the central idea of the paper which is to explicitly induce clustering among contending nodes to achieve even better spatial reuse. We propose two distributed mechanisms to realize such clustering and show substantial capacity gains over simple random access/ALOHA-like and even RTS/CTS based protocols. We examine under what regimes such gains can be achieved, and how clustering and contention resolution mechanisms should be optimized to do so. We propose the design of ad hoc networks supporting hop-by-hop relaying on different spatial scales. By allowing nodes to relay beyond the set of nearest neighbors using varying transmission ranges (scales), one can reduce the number of hops between a source and destination so as to meet end-to-end delay requirements. To that end we propose a multi-scale MAC clustering and power control mechanism to support transmissions with different ranges while achieving high spatial reuse. The considerations, analysis and simulations included in this paper suggest that the principle of inducing spatial clustering in contention has substantial promise towards achieving high spatial reuse, QoS, and energy efficiency in spread spectrum ad hoc networks.

In this paper, upper and lower bounds on the transmission capacity of spread-spectrum (SS) wireless ad hoc networks are derived. We define transmission capacity as the product of the maximum density of successful transmissions multiplied by their data rate, given an outage constraint. Assuming that the nodes are randomly distributed in space according to a Poisson point process, we derive upper and lower bounds for frequency hopping (FH-CDMA) and direct sequence (DS-CDMA) SS networks, which incorporate traditional modulation types (no spreading) as a special case. These bounds cleanly summarize how ad hoc network capacity is affected by the outage probability, spreading factor, transmission power, target signal-to-noise ratio (SNR), and other system parameters. Using these bounds, it can be shown that FH-CDMA obtains a higher transmission capacity than DS-CDMA on the order of M/sup 1-2//spl alpha//, where M is the spreading factor and /spl alpha/>2 is the path loss exponent. A tangential contribution is an (apparently) novel technique for obtaining tight bounds on tail probabilities of additive functionals of homogeneous Poisson point processes.

Upper and lower bounds on the transmission capacity of direct-sequence CDMA wireless ad hoc networks are derived. The transmission capacity is a stochastic measure of the allowable number of transmissions per unit area, and is a generalization of previous measures of ad hoc network capacity. Successive interference cancellation (SIC) is attractive for DS-CDMA ad hoc networks since the dominant nearby interferers can be cancelled. Our closed-form results cleanly summarize the dependence of ad hoc network capacity on pathloss, spreading, outage probability, and interference cancellation accuracy. Other multiple access schemes, such as CSMA and DS-CDMA without SIC, are special cases. Perfect interference cancellation increases transmission capacity by nearly two orders of magnitude. Furthermore, cancelling just the strongest interferer generally gives the majority of the capacity gain, so the latency and complexity cost of SIC should be negligible.

We study the 'service capacity' of peer to peer (P2P) file sharing applications. We begin by considering a transient regime which is key to capturing the ability of such systems to handle bursty traffic, e.g., flash crowds. In this context our models, based on age dependent branching processes, exhibit exponential growth in service capacity, and permit the study of sensitivity of this growth to system policies and parameters. Then we consider a model for such systems in steady state and show how the average delay seen by peers would scale in the offered load and rate at which peers exit the system. We find that the average delays scale well in the offered load. In particular the delays are upper bounded by some constant given any offered load and even decrease in the offered load if peers exit the system slowly. We validate many of our findings by analyzing traces obtained from a second generation P2P application called BitTorrent.