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Development of fair and efficient algorithms for resource allocation to secondary users (SUs) is one of the key issues in the design of cognitive radio (CR) systems. In this paper, we present a two-step resource allocation solution for multiuser based CR systems employing orthogonal frequency division multiplexing (OFDM). The solution allocates the subcarriers to SUs in the first step, considering...
Cognitive radio (CR) employing OFDM has drawn many interests in designing efficient radio resource allocation schemes. Most of the existing works considered the cognitive scenario under perfect knowledge of system state, such as channel state information (CSI) and sensing information (SI). However, it is serious to properly regulate the interference caused by secondary users (SUs) to each primary...
Cognitive radio is an emerging technique to improve the utilization of the scarce radio frequency spectrum, which is characterized by the dynamic spectrum access of the secondary users coexisting with the primary users. In cognitive radio network, secondary users strive for temporally unused spectrum access opportunities offered by primary services; as a result, the opportunistic nature of the spectrum...
The instable user behavior and the burst traffic usually induce low utilization of spectrum resource in single wireless network. This paper proposes a novel spectrum borrowing scheme which allows spectrum borrowing between heterogeneous wireless networks to more efficiently make use of limited radio resource. The proposed scheme is based on the model composed of TD-SCDMA (time division-synchronous...
We have developed a new Self-aligned poly (SAP) process to improve the tunnel oxide integrity by optimizing the shallow trench isolation (STI) corner rounding profile and reducing the local oxide thinning effect. It is found that double in-situ steam generation (ISSG) liner oxides can effectively improve the STI corner rounding. As for the local oxide thinning effect, the composite pad dielectrics...
This investigation employs an optimized method to alleviate defects occurring at BF2+ implanted source/drain areas, some white spots defects found at scribes lines after BPSG (boron and phosphorus doped silicon glass) anneal. The results of physical failure analysis indicate the white spot defects are relative to outgassed fluorine that can't be released out during BPSG thermal annealing. Various...
This paper presents a unique gate structure for reducing shorts between word lines on charge-trapping flash cell memory. In the early stage of developing sub-45 nm half-pitch word line by a self-aligned double patterning (SADP) technology, the cell array suffered from abnormal intrinsic word line-to-word line shorts, ca. 96.3% of the bridge rate on the 72 Mb cell memory, due to the formation of polysilicon...
In this paper, we present a distributed relay selection and power allocation scheme concurrently considering the channel states of all related links and residual energy state of the relay nodes for cooperative transmission in cognitive radio (CR) networks. Specifically, we formulate the CR network with cooperative transmission as a restless bandit system, which has been widely applied in operations...
Due to the heterogeneity and versatility of emerging services and applications in wireless networks, it has been a great challenge on improving the network utility by taking advantage of the spatial and temporal diversity of radio resource consumption. This paper is committed to solving this problem by introducing a service-aware spectrum sharing algorithm (SSA) in a joint radio resource management...
Cooperative communication is an emerging and effective technology which can overcome the limitation and improve overall system performance of wireless networks. As important design parameters, relay selection, power and bandwidth allocation have been investigated respectively in previous literature. However, most of the existing schemes mainly consider single-relay selection, which may result in imbalance...
In cognitive radio networks (CRN), underlay spectrum sharing allows secondary users (SUs) to utilize the spectrum on which the primary users (PUs) in primary radio networks (PRN) are working at the same time, without introducing intolerant interferences. In this paper, we study the joint transmission power and time allocation in CRN with underlay spectrum sharing technology. To maximize the total...
As heterogeneous wireless networks are deployed and users need more flexible mobility services, there has been a lot of research work about interworking mechanism between widely deployed 3G network and rapidly boarded WLAN (wireless local area network). On the other side, TD-SCDMA (time division-synchronous code division multiple access), which combines all the advantage of the TDD (time-division...
Cognitive WLAN over Fiber (CWLANoF) is proposed as the improved architecture of traditional WLANs. In this paper, the channel allocation problem for hot spot in CWLANoF is firstly established as a restless bandit problem, which is solved by the primal-dual index heuristic algorithm based on the first order relaxation due to less complexity. Moreover, the proposed scheme is divided into offline computation...
So far, Rough Set Theory has already become the focus-studied in international artificial intelligence. This thesis is based on Rough Set Theory, which has the following innovation. It gives a new kind of arithmetic of attribute reduction, that is to say, making use of attribute resolution stage through truth which indicates this reduction is an effective reduction.
The conspiracy attack on (t,n) threshold signature is still an open problem. For solving the problem, this paper proposes a new signature scheme, which is based on the idea of opening the sets of ID authentication information. Using two sets of secret key algorithm, the scheme attaches a secret random ID authentication information to the shareholder's secret key and provide a verify equation for the...
In cognitive radio (CR) networks, the multichannel access problem is an important problem, which may directly affect user applications. However, most of previous work on this problem focuses on maximizing physical layer throughput, rather than the end-to-end transmission control protocol (TCP) performance. In this paper, we propose an optimal TCP throughput based channel access scheme in CR networks,...
Aiming to eliminate the mismatch between structured peer-to-peer (P2P) network's logical topology and physical topology, which exists in these classic wired P2P protocols, the representative P2P protocol-Chord which is hardly suitable for wireless network is modified, and an approach of getting optimal node identifier (ID) to realize topology awareness is proposed by exploiting nodes' relative location...
Combined with the established three-dimensional dynamic solidification heat transfer model, a feed-forward controller under speed disturbance was designed for compensating secondary water. In order to improve the control quality of the surface temperature for billet, based on the determination of the transfer function matrix structures of the control channel and the disturbance channel, the heat transfer...
In this paper, we propose an optimal TCP throughput framework to optimize the TCP throughput in CR networks, which jointly considers the channel sensing decision and access policy as well as low layer design parameters. The TCP throughput optimization is achieved by a two step process. First, we select a channel to maximize the spectrum utilization by reducing the probability of collision with primary...
In order to match logical topology to physical topology in P2P wireless network, a new protocol based on chord is proposed, in which a node can get a optimal node identifler(ID) to realize topology awareness by exploiting nodes' relative location information, which is reflected on the energy strength of received signal and the distribution density of P2P member. Simulation results show that the wireless...
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