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In this paper, the influence of feedback channel delay on system throughput of the cooperative multi-cell system with adaptive beamforming selection is discussed. On the one hand, multi-cell cooperative processing (MCP) has the potential to boost spectral efficiency and improve fairness among users. However, the traditional centralized multi-cell cooperative scheme, where a central processing unit...
To deal with problems that queuing information is not included in cognitive information when performing Resource Allocation (RA), a dynamic cross-layer scheme is proposed for the multimedia cognitive radio (CR) system with Orthogonal Frequency Division Multiplexing (OFDM). In this scheme, we consider that several crucial factors influence the RA decision, including channel state information, interference...
In Wireless Local-Area Networks (WLANs), most of the wireless Access Points (APs) work at the full power level. So, the conflicting channels may have a significant and inevitable impact on throughput and transmission delay when the density of the APs is increasing. This paper proposes a power control algorithm, Dynamic Power Control called DPC based on NetFlow. DPC applies a fine tuning idea to get...
Due to overlapping frequency bands, IEEE 802.11a WLAN and Ultra Wide-Band systems potentially suffer from mutual interference problems. This paper proposes a method for inserting frequency notches into the IR-UWB power spectrum to ensure compatibility with WLAN systems. In contrast to conventional approaches where complicated waveform equations are used, the proposed method uses a dual-pulse frequency...
Interference management is an important issue due to the wide deployment of femtocells by subscribers. An elementary solution to the interference mitigation problem is to restrict transmission of pilot signals by femto base stations (BSs) which have no serving subscribers, i.e. idle listening state operation. However, the implementation of the idle listening state in a femto BS opens a possibility...
Inter-cell Interference (ICI) in the uplink of modern cellular communication systems with high frequency reuse is hard to predict, as fast scheduling and link adaptation lead to a high interference fluctuation. This fluctuation poses a big challenge for link adaptation algorithms that need an accurate SINR estimate to assign suitable modulation and coding schemes for transmission. To enable ICI prediction...
This paper studies the capacity performance of coordinated multi-point (CoMP) downlink transmissions based on limited feedback. We consider both path loss effects and channel imperfections including feedback delay and quantization error. Closed-form expressions are derived to characterize ergodic achievable rates for joint processing (JP) and coordinated beamforming (CBF) techniques, respectively...
Coordinated multi-point (CoMP) transmission is considered as an efficient technique to improve cell-edge performance as well as system spectrum efficiency. In CoMP-enabled systems, a cluster of coordinated base stations (BSs) are typically assumed to be connected to a control unit (CU) via backhaul links, and the provided performance gain relies heavily on the quality of the channel state information...
Resource allocation is a critically important issue for cognitive networks, because it needs to not only meet the quality-of-service (QoS) requirements for the secondary users (SU), but also protect the QoS of primary users (PU) from degradation. In this paper, we develop the optimal power allocation scheme for the cognitive network, which can satisfy the QoS requirements of SUs and PUs simultaneously...
This paper studies a spectrum sharing cognitive radio (CR) network coexisting with a primary network. In particular, the channel state information (CSI) between the secondary transmitter (STx) and the primary receiver (PRx) is assumed to be outdated due to channel feedback latency. We assume that the secondary user (SU) shall satisfy a given delay quality-of-service (QoS) constraint as well as the...
In this paper, we will illustrate a practice of pipeline process to maximize the parallelization of all possible interference-free relays in the broadcasting of wireless sensor networks (WSNs), in order to optimize the end-to-end delay performance in both the (synchronous) round-based systems and the (asynchronous) duty cycle systems. Broadcasting is one of the fundamental communications in WSNs....
In this paper we validate and extend through simulations the trends revealed by the analytical results of our prior work concerning the throughput-delay trade-off that can be achieved by forwarding schemes exploiting path diversity and different degrees of redundancy focusing on the case of hop-by-hop retransmissions at the link-layer. The simulation environment is based on 802.11 Physical and Mac...
Noncoherent UWB receivers promise low power consumption and low processing complexity but their peak data rate is limited by the delay spread of the multipath radio channel. A recently proposed multichannel autocorrelation receiver (AcR) can break this rate limit due to its multicarrier signal demodulation capability. In this paper, the hardware implementation of this receiver architecture is addressed...
Multi-core virtualization platform is an essential basement of modern computing environment including server consolidation and cloud computing. However hidden contention for physical resources between different workloads always causes serious performance interference and thus reduces system performance and efficiency. In order to address this issue, we exploit the possibility of scheduling virtual...
Primary results of fundamental research in the field of radar theory are presented. The novelty of the research consists in the following: within the scope of energy conservation law and Bayes statistical decision theory a new approach to the process of target radar signals detection on the basis of energy criterion is considered. A condition for radio-signals optimal energy detection against a background...
In mobile cognitive radio networks, the expected delay for a packet to be delivered to its destination via a singlehop communication (without relaying) is a fundamental metric that can provide a guidance to multi-hop routing protocol design and route planning. In this paper, we characterize the impact of PU activities, spectrum availabilities, channel bandwidth, MAC access, SU mobilities, and interference,...
Wireless mesh networks (WMNs) have been increasingly used to carry multimedia traffic with flow requirements. The performance of multi-radio multi-channel (MRMC) WMNs largely depends on the routing and channel assignment. Because routing and channel decisions are coupled, they need to be jointly optimized to achieve the best performance. This is the so-called routing and channel assignment (RCA) problem,...
Space Wire is a standard of on-board networks for satellites promoted by the ESA. As the ESA plans to use Space Wire as the sole network for both critical and non-critical traffics, network designers need tools to check that all the critical messages meet their deadlines. We previously proposed two such tools to compute an upper-bound on the worst-case end-to-end delay of a packet traversing a Space...
Shared resource access interference, particularly memory and system bus, is a big challenge in designing predictable real-time systems because its worst case behavior can significantly differ. In this paper, we propose a software based memory throttling mechanism to explicitly control the memory interference. We developed analytic solutions to compute proper throttling parameters that satisfy schedulability...
Some analyses and researches are done about networked control systems (NCS) those are based on the new Smith predictor and internal model control (IMC) from the system structures in this paper. The research and simulation results show that the choice of strategy of the new Smith predictor is more flexible than internal model control, but the adjusting parameter of the internal model control is relatively...
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