Tiecheng Song

Demand-matching spectrum sharing game for non-cooperative cognitive radio network

In cognitive radio network, efficient spectrum sharing is one of the important functions which can enhance the overall spectrum utilization of whole network. However, it is still an unexplored issue to make unlicensed users choose the most suitable spectrum according to user demand and the spectrum characteristics. In this paper, a new Demand-Matching Spectrum Sharing (DMSS) algorithm based on game theory for non-cooperative cognitive radio network is proposed. Firstly, the model of the matching factors between the user demand and the spectrum characteristics is built up. Then by adopting demand-matching factor, the DMSS game is proposed and Nash equilibrium is solved by Nelder-Mead direct search method. DMSS enables each unlicensed user to access multiple appropriate channels by maximizing its own payoff. Numeral results reveal that DMSS achieves high performance in spectrum utilization percentage and spectrum efficiency of cognitive radio network when it reaches Nash equilibrium.

Modeling for spectrum handoff based on secondary users with different priorities in cognitive radio networks

Storaci-Cognitive radio (CR) can improve spectrum utilization by allowing the secondary users to temporarily access the primary users unutilized licensed spectrum. In fact, the secondary users delay requirements for data transmission would be not unitary. Some secondary users communications may be delay-sensitive such as VoIP service while some others may not such as uploading a large file. In this paper, secondary users are divided into two classes, class-1 secondary user denoted by SUI and class-2 secondary user denoted by SU2. Suppose SUI has a higher priority than SU2 to occupy the channels. In order to characterize the cumulative handoff delay of the secondary users with different priorities, a Markov transition model integrating with the preemptive resume priority (PRP) M/M/2 queuing network is investigated. The numerical results compare the handoff delay between the unitary secondary users and different priorities secondary users. The analysis of the admission region for SUI and SU2 can also facilitate the designs of admission control rules according to the latency delay requirements of different transmission services.

Optimal sensing time of soft decision cooperative spectrum sensing in cognitive radio networks

Spectrum sensing is a key feasible technology for cognitive radio (CR). Sensing time is an important sensing parameter which brings about a sensing-throughput tradeoff. In this paper, based on soft decision schemes, we investigate the sensing-throughput tradeoff problem and analyze the impact of different system parameters on the optimal sensing time for cooperative spectrum sensing. Simulation results show that maximal ratio combination g (MRC) and modified deflection coefficient (MDC) schemes have almost the same performance which outperform equal gain combination (EGC) scheme. Further, optimal sensing time decreases with the increase of number of CR users and increases when average signal-noise-ratio (SNR) decreases.

Spectrum Sensing and the Utilization of Spectrum Opportunity Tradeoff in Cognitive Radio Network

Cognitive radio (CR) is proposed to use the spectrum opportunistically. In this letter, we study the tradeoff between the spectrum sensing performance and the utilization of spectrum opportunity in the CR network. We formulate the tradeoff problem mathematically. The optimum tradeoff mainly depends on the activity of primary user. Cooperative spectrum sensing is also studied based on the methodology of the proposed tradeoff problem. We perform the numerical analysis to quantify the effects of different parameters on the optimal spectrum sensing time.

Improved EM method for internet traffic classification

Network traffic classification algorithm based on the machine learning has attracted more and more attention. Because the traditional EM algorithm has the disadvantage that the algorithm has the sensitivity of initial value and converge to local optimal point easily. This paper proposed a new improved EM algorithm based on the q-DAEM. The improved algorithm applies the EM algorithm to generate a constrained matrix, then combine the constrained matrix with the q-DAEM algorithm to reduce the search range, so that a better Gaussian mixture model can be derived from this algorithm. The algorithm was applied to the Moore datasets for evaluation, the experimental results show that this improved algorithm which applied to network traffic classification can lead to a higher precision and overall accuracy.

Improved OFDMA Uplink Resource Allocation Algorithm Based on Message Passing

A distributed subchannel assignment scheme for OFDMA uplinks via batchwise message passing (MP) is proposed. Each batch of iterations completes partial allocation of subchannels resulting in partial withdrawal of the subchannels and users. This saves the subsequent consumption of message and speeds up its updates. Moreover, the modification of Hoares FIND (HF) algorithm gains a further speedup of updates of the message. An average computation speedup of around 3x and message saving of nearly 20% over SF-MP scheme is achieved.

Intercept probability analysis of relay selection for wireless communications in the presence of multiple eavesdroppers

In this paper, we consider a cooperative relay network consisting of a source, a destination, and multiple decode-and-forward (DF) relays in the presence of multiple eavesdroppers, which intend to tap confidential messages transmitted by both the source and the relays. We propose a so-called secrecy maximization oriented relay selection (SMORS) scheme to improve the physical-layer security of wireless communications. In the SMORS scheme, a relay with the maximal secrecy rate is selected among all the DF relays to forward the source signal. We analyze the intercept probability of the proposed SMORS scheme as well as the traditional max-min relay selection scheme. Numerical results show that the proposed SMORS scheme outperforms the conventional max-min relay selection scheme in terms of the intercept probability. Additionally, it is shown that with an increasing number of eavesdroppers, the intercept performance of wireless communications degrades, which can be well addressed using the proposed SMORS scheme through increasing the number of relays. By contrast, increasing the number of relays has little impact on the intercept probability for the conventional max-min relay selection scheme, especially when the number of relays is sufficiently high (e.g., exceeding 20 relays).

Interference Minimization Approach for Joint Resource Allocation in Cognitive OFDMA Networks

In this paper, we propose a novel resource allocation (RA) scheme based on interference minimization (IM) for cognitive radio networks (CRN). In the approach, we focus on an efficient scheme of subchannels assignment, power allocation and access control for the orthogonal frequency division multiple access (OFDMA)-based secondary users (SUs), accessing licensed spectrums of primary users (PUs) with underlay approach. Different from traditional schemes, we consider more for PUs capacity protection, by taking the interference introduced to PUs as minimization objective. Compared with other schemes, the simulation results show that our proposed scheme can reserve more PUs capacity, while guaranteeing the rate and the Quality of Service (QoS) of SUs.

Design and implementation of power communication terminal based on link aggregation technology

An aggregation terminal of the power communication system is proposed in this paper. The terminal takes Samsung Corporations ARM9 S5PV210 processor as the hardware core, embedded Linux as the operating system. The high-definition network camera is used as the video monitor device, whose interface is Ethernet. The terminal is equipped with 3G/4G LTE and various communication modules and the drivers are transplanted on the ARM Linux system. Based on the link aggregation and the SOCKET communication technology, the software program is designed as the C/S mode using multiple threads of C language. According to experiment results, the terminal can meet the requirements of the video service in the process of electric power communication, improving the efficiency and saving the cost of construction.

Relay selection for enhancing wireless security-reliability tradeoff in the presence of channel estimation errors

In this paper, we investigate the physical-layer security for a wireless two-hop relay network in the presence of channel estimation errors when estimating the channel state information (CSI) of the main links (from the source via relays to the destination) and wiretap links (from the source and relays to the eavesdropper). The eavesdropper can not only overhear the confidential signals transmitted by the relays, but also tap the secret messages transmitted by the source. We present an channel estimation error oriented relay selection (CEEoRS) scheme to improve the security-reliability tradeoff (SRT). We also analyze the intercept probability and outage probability of the CEEoRS scheme, where the intercept probability and outage probability can quantify the security and reliability, respectively. For comparison purposes, the traditional direct transmission with channel estimation errors (TDTwCEE) is also analyzed. It is shown that the proposed CEEoRS scheme outperforms the TDTwCEE scheme in terms of its SRT. More specifically, the proposed CEEoRS scheme is capable of significantly improving the SRT performance of wireless communications through increasing the number of relays.