Earticle

This paper proposes a resource allocation strategy for multi-channel underlay cognitive radio (CR) systems by means of an ensemble deep learning framework. The transmit power of secondary users (SUs) allocated to each channel is determined to maximize the overall spectral efficiency (SE), whilst meeting the interference constraint on the primary user (PU). To this end, a deep neural network (DNN) structure is developed, in which multiple DNN units are jointly utilized, to obtain the diversity over different DNNs. Our simulation results confirm that the proposed scheme can achieve near-optimal performance with a low computation time of less than 1.5 ms.

현재 국내 라디오 방송은 디지털 방식이 아닌 아날로그 방식을 통해 서비스 되고 있다. 디지털라디오란 기존의FM/AM 라디오를 디지털 신호로 전송하는 것으로 보다 깨끗한 음질과 교통, 날씨정보 등 다양한 부가 서비스를 제공할 수 있다는 장점이 있다. 이 밖에도 라디오가 디지털로 전환되면 갈수록 늘어나는 FM 주파수에 대한 수요도 충족시킬 수 있을 것으로 기대하고 있다. 디지털 라디오 방식중 하나인 DRM+는 배치하고자하는 지역의 주파수 사용현황에 따라 상대적으로 간섭이 적은 대역이라면 어디든 배치할 수 있다. 본 논문에서는 DRM+ 시스템에 대해 간단히 설명하고, 현재 사용 중인 주파수 현황을 알아본 후, 그에 맞는 DRM+후보 채널 도출 방안을 제시하고, 기존 아날로그 방송과DRM+의 전파 간섭영향을 모의실험을 통해 검증 하였다.

The Korean radio broadcasting system is analog. Digital Radio will transmit a digital signal to existing analog FM/AM. It provides clear sound quality, traffic information, weather information and various value-added services. In addition, the converted digital radio will be able to meet demand to growing demand for analog FM. DRM + is an area to place, depending on the frequency of usage to less interference can be placed anywhere. In this paper, DRM + system, a brief description, and is currently using the frequency status were described, accordingly DRM + candidate channel derived measures proposed, the existing analog broadcast and DRM + of interference effects through the simulation has been verified.

사물인터넷 환경에서 동작하는 기기들은 제공하는 서비스의 목적에 맞도록 다양한 무선 통신 기 술을 사용한다. 특히, 다양한 무선 기술들이 서로 통신 가능한 거리에 존재할 때 서로 다른 PHY/MAC 계층의 특성으로 인해 다른 무선 기술의 성능을 저하시킬 수 있다. 따라서, 이종 무선 기술들 간의 상 호 공존을 위한 기술들이 주요 이슈로 부각되고 있으며 이들 간의 심각한 간섭을 완화시키기 위한 새 로운 적응형 계층의 필요성이 부각되고 있다. 본 논문에서는 Wi-Fi 네트워크와 ZigBee 네트워크가 함 께 동작할 때 발생하는 문제점을 확인하고 이를 해결하기 위한 분산적인 채널 선택 기법을 제안한다. 이종 무선 네트워크가 공존하는 경우 서로 다른 전송 특성으로 인해 비대칭적인 간섭 현상이 발생하 게 된다. Wi-Fi의 경우 ZigBee 기기들보다 더욱 강한 세기로 데이터를 전송하기 때문에 ZigBee 노 드들의 전송 성능을 심각하게 저하시킬 수 있다. 또한, Wi-Fi 네트워크는 시간, 주파수, 공간영역에서 다양한 간섭 패턴을 발생시켜 ZigBee 기기들의 데이터 전달 지연 시간 및 에너지 소모량에 영향을 주 게 된다. 제안한 기법은 이러한 Wi-Fi 간섭의 영향을 최소화하기 위해서 ZigBee 기기들 관점에서 채 널 상태를 모니터링하고 Wi-Fi 간섭이 최소가 되는 채널 리스트를 구성하여 송신 및 수신 동작을 수 행하여 네트워크 성능을 향상시킨다. 본 논문에서는 이벤트 기반의 시뮬레이션 결과를 바탕으로 제안 한 채널 할당 기법의 우수성을 증명하였다.

The wireless devices operated in the Internet of Things(IoT) environment use diverse wireless technologies to support intelligent IoT services. Particularly, due to the different PHY/ MAC specifications among those wireless technologies, they can negatively affect their entire network performances. To mitigate severe interferences, an efficient coexistence scheme between the heterogeneous networks are becoming key issues. In this paper, we propose a novel distributed channel selection scheme of a ZigBee network to reduce the impact of the severe interference from a Wi-Fi network. Various different characteristics of heterogeneous networks result in asymmetric interference patterns. Since a Wi-Fi device transmits data packets with a higher transmission power than a ZigBee device, it aggravates the overall ZigBee performances. In addition, the Wi-Fi network generates various interference patterns in the time, frequency, and spatial domains, thereby affecting transmission delay and energy consumption of ZigBee devices. In order to minimize the impact of a Wi-Fi interference, the proposed scheme adopts an accurate channel monitoring scheme from the viewpoint of ZigBee devices and performs transmission and reception operations based on the constructed channel list. We show the superiority of the proposed scanbased channel allocation scheme via an event-driven simulation.

최근 방송 기술에 디지털 방식의 도입으로 인해 방송 환경의 급격한 변화가 이루어지고 있다. 현재 다수 국 가에서는 아날로그 라디오를 디지털 라디오로 전환하기 위한 기술 도입이 진행 중이다. 하지만 국내의 경우 아직 표 준 기술도 결정되지 않았다. DAB와 DRM+ 방식은 아날로그 라디오 대역 외의 다른 주파수에서 사용 가능하다. 따라 서 본 논문은 두 방식을 동시에 사용하는 방안을 고려하였다. T-DMB대역에서 간섭을 주지 않도록 DAB 시스템을 배치하여 방송할 경우 주파수 자원 부족에 의해 간섭이 발생한다. 간섭이 발생한 지역 채널을 상대적으로 대역폭이 좁은 DRM+ 시스템으로 대체하여 간섭을 해결하는 방안을 고려하였다. 간섭 분석 시뮬레이션 결과 DAB 환경에서의 고 간섭 지역이 해결된 것을 확인할 수 있었다.

Recently, broadcasting environment is dramatically changed due to adopt digital method in broadcasting technology. numerous country is adopting technology for converting analog to digital. However, in the case of South Korean, standard is still indefinite. In this paper, when it broadcast using DAB system, in oder to avoid interference caused by the frequency resource shortage, DAB system is substituted narrow bandwidth DRM+ system. Therefore it considers the way that solve interference. Interference analysis simulation result shows to solve high interference area in DAB environment

This paper aims to enhance efficiency of management through physical, logical consumer channel clustering and reliability on metering reading data, and achieve expandability of wireless metering reading network through channel use that can be identified between proximate clusters, by suggesting channel set-up based on multichannel cluster mixed with network channel and group channel to resolve the problems and implement various services. Further, the article aims to reduce installment time and maintenance repair cost through hierarchical network structure composed with four differentiated devices in wireless AMR systems, and suggest wireless AMR network based on multichannel cluster substantializing various services by supporting various movement modes through quick error recovery and back up functions. The AMI Network is based on multichannel cluster mixed with network channels and group channels, which increases management efficiency through channel clustering of physical, logical consumer, and enhances reliability on meter reading data through channel use which can be identified between geographically proximate clusters.

This paper considers WiMedia UWB network based wireless ship area network (WSAN) so as to support high-quality multimedia video data services and important shipboard control data. In this paper, prioritized contention access (PCA) and distributed reservation protocol (DRP) based on WiMedia UWB (ECMA- 368) MAC protocols are combined and proposed to support mixed high-quality video traffic and shipboard control data traffic applying varying DRP and PCA data periods according to channel condition and link parameter ptimization. It is shown that the proposed dynmaic channel allocation of WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well.

Cognitive radio network was proposed to use the spectrum resource more efficiently. In a multichannel ad-hoc cognitive radio network, there is no central station and requires distributed channel scheduling. An important requirement of the cognitive radio network is to avoid interference to primary networks. In this paper, the authors propose the distributed packet scheduling scheme for ad-hoc multichannel cognitive radio networks. Each secondary user calculates independently its own priority with probabilistic manner and selects one of multi channels considering the primary user’s traffic pattern to minimize interference to the primary networks.

The efficient management and sharing of the radio spectrum among numerous users become an important issue. The frequency channels are a scarce resource in a cellular mobile system. Thus, many schemes have been proposed to assign frequencies to the cells such that the available spectrum is efficiently used. In this paper, we propose a channel allocation mechanism including migration concept using genetic algorithm in cellular mobile computing environments. Our simulation results indicate that the proposed algorithm could reduce a search time for an available channel.

In this paper, a Dual Channel Allocation (DCA) Scheme for UWB (Ultra Wide Band) with D-MAC (Distributed Medium Access Control) is proposed. Since distributed characteristic of the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme may cause lots of conflicts, overall performances of the WiMedia D-MAC can be deteriorated. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a DCA mechanism to avoid DRP conflicts by providing a cooperative relay transmission scheme and demonstrate its performance improvements via simulation results.

The channel allocation is one of the key problems in the design of the wireless network, as it greatly influences the throughput and performance of the network. Firstly we introduce the channel propagation model, which is able to accurately reflect the signal attenuation, the network interference and other factors in the actual environment. Based on this work, we put forward the channel allocation algorithm named LRCAA, which includes two parts: the pre-allocation stage and the dynamic optimization stage. The LRCAA is verified by the experiment, which shows it can converge to a stable optimal point and obtain a better network performance.

This paper proposes a fuzzy logic control based dynamic channel allocation (DCA) to ECMA-368 based WiMedia UWB networks, which aims to support mixed high-quality video traffic and shipboard control data traffic with high reliability and priority as well. The DCA method applied in this paper is to flexibly vary the portions of time slots of either the prioritized contention access (PCA) or the distributed reservation protocol (DRP), according to traffic condition and priority. Furthermore, the proposed DCA with the fuzzy logic control algorithm can intelligently divide the portion of time slots and allocate channels to both PCA and DRP, resulting in support of both HD-video stream services and shipboard instrument control data. It is shown that the proposed fuzzy logic controlled DCA with WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well, and it can provide better performance of the aggregated throughput than that of without fuzzy logic control algorithm.

Hyper-spectral Atmospheric Infrared Sounder AIRS has many channels. Taking into account the correlation between channels, different detection purposes and the timeliness of assimilation, channel selection is necessary. Principal component-dual-zone-stepwise regression method is proposed in this paper and points the day and night for channel selection. The contribution rate of channel observation brightness temperature to the objective function is controlled by channel observation error, variational data assimilation system is generally given observation error and then in the process of minimization objective function remains unchanged, the paper adopt the observation error re-estimated and then provide observation error information to the variational data assimilation. Study effects of channel selection and the observational error allocation on the assimilation of AIRS data in this paper.

In the light of the characteristics of random change that underwater sensor change by time, space and frequency, select the best relay node to improve communication quality and get the diversity gain. A new optimal relay selection method is proposed in this paper, by considering two indexes synthetically that channel gain and underwater acoustic communication long time delay to select the best relay node. Based on the best relay node and minimization of bit error rate to take optimal power allocation of source node and relay node to realize network error rate’s reduction of 1.81 dB so then improve the overall performance of the network.

This paper proposes an improved wireless communication channel reservation policy to address the impact on network performance cannot be analyzed under the original model with the primary and secondary users communication channel occupancy rates, and the problem that the secondary user blocking state is significantly higher than the primary user blocking probability under the original model. Simulation results show that improvement in network performance can be done by increasing the primary user communication channel occupy completion rate and the secondary user communication channel occupy completion rate. Also different users channel using request blocking probability can be reduced. It is more effective. That to improve the mixing network performance by improvement of secondary user communication channel occupy completion rate. The new improved model is important in ensuring the coal mine communication system (primary user) as the coal mine wireless communication system for emergency protection. Also the blocking probability of secondary users was reduced. The network access performance of the secondary user was enhanced and improved. The fairness among different users access to the hybrid network was ensured.

Recently, the issue of excessive energy consumption in wireless communications has become increasing critical, and the energy harvesting as a renewable energy resource, has received extensive attractions. In this paper, a wireless sensor network (WSN) is considered, where the source-destination pair communicates via an energy harvesting relay links. We study the problem of the harvested energy distribution among the source, relay and destination nodes. An effective power allocation scheme is developed which exploits the decode-and-forward (DF) relaying strategy and channel state information. The outage probability is analyzed and simulation results show that the outage performance for two sub-channels is always performs well in the cases of different threshold target data rate. Moreover, the effect of the different radio of the optimal sub-channel gain and Rayleigh channel gain on the outage performance is evaluated.

우리나라의 지상파 방송은 TV와 라디오, DMB가 있다. TV가 2012년 말 디지털 방식으로 전환이 완료됨에 따라 라디오만이 유일한 아날로그 방식의 방송으로 남아있게 되었다. 디지털 라디오 기술의 도입은 고품질의 소리와 다양한 부가서비스 제공, 방송 주파수 사용에 있어 효율성 증대 등 많은 이익을 가져올 것이다. 이미 많은 나라에서는 디지털 라디오 방송을 제공하고 있고, 우리나라에서도 올해 본격적으로 디지털 라디오 기술을 도입하기 위한 논의가 시작되었다. 이에 본 논문에서는 디지털 라디오 기술 중 하나인 DAB 시스템 도입에 대비하여 각 지역 라디오 방송에 대한 DAB 가용채널 배치와 함께 전국 SFN 방송망을 구성하는 방안을 제안하고, 시뮬레이션을 통해 간섭 영향을 분 석하여 제안한 방안을 검증하였다.

The Korea terrestrial broadcasting has TV and Radio, DMB. The TV broadcasting was converted from the analogue method to the digital method at the end of 2012. However the radio broadcasting is still in analogue method. The introduction of digital radio technology will bring many benefits such as high-quality of sound, various additional services and increase of efficiency in frequency utilization. In many countries, the radio broadcasting is been servicing in digital method. The discussion was begun on this year for the introduction of digital radio technology in Korea. So, to prepare against introduction of DAB system among digital radio technology, this paper proposes channel allocation method for each local radio broadcasting and the composition of national SFN, and proves the proposed method through the interference analysis.

데이터 할당 기술은 데이터 방송 시스템의 성능을 향상시키기 위해서 필수적이다. 본 논문은 질의 프로파일과 질의 요청 확률이 주어진 환경에서 다중 데이터 질의를 처리하기 위하여 방송채널에 데이터를 할당하는 주제를 연구하여 QBDA(Query-Based Data Allocation)로 명명된 새로운 데이터 할당 기법을 제안한다. 제안된 기법은 요청율이 높은 질의에 우선권을 주어 데이터를 스케줄링하며, 데이터 충돌을 줄이기 위하여 마킹 개념을 도입한다. QBDA 기법의 성능 평가를 위해 시뮬레이션이 수행되었다. 실험 결과에 따르면, 제안된 기법은 요청 확률이 높은 질의들을 빠르게 처리할 수 있을 뿐만 아니라 질의 데이터 인접성 및 데이터 충돌 확률 측면에서 매우 바람직한 특성을 보이기 때문에 평균 응답시간의 성능에서 다른 기법보다 우수한 성능을 보인다.

A data allocation technique is essential to improve the performance of data broadcast systems. This paper explores the issues for allocating data items on broadcast channels to process multiple-data queries in the environment where query profiles and query request rates are given, and proposes a new data allocation scheme named QBDA. The proposed scheme allows the query with higher request rate to have higher priority to schedule its data items and introduces the concept of marking to reduce data conflicts. Simulation is performed to evaluate the performance of QBDA. The simulation results show that the proposed scheme outperforms other schemes in terms of the average response time since it can process queries with high request rate fast and show a very desirable characteristics in the aspects of query data adjacency and data conflict probability.

방송 기반의 데이터 전파는 모바일 컴퓨팅 환경에서 보편적으로 받아들여지는 통신 방식이다. 그러나 많은 데이터를 방송해야 할 경우에 방송 채널의 순차성으로 인하여 원하는 데이터를 수신하기까지의 예상 지연시간이 증가한다. 이 대기시간을 줄이기 위하여 본 논문은 다중 채널에 적절하게 데이터를 할당하기 위한 주제를 연구하여 NODA(near optimal data allocation)로 명명된 새로운 데이터 할당 기법을 제안한다. 제안된 기법은 우선 각 방송 채널이 방송해야 하는 데이터들을 결정하기 위하여 평균 예상지연시간의 이론적 하한 값에 기초하여 전체 데이터들을 K 개의 그룹으로 분할한다. 그리고 나서 NODA는 동일 방송 채널에 할당된 데이터들을 다른 빈도로 방송하기 위하여, 각 그룹의 데이터들을 확장된 동적 프로그래밍 알고리즘을 사용하여 B 개의 그룹으로 분할한다. 제안된 기법은 동일 채널에 할당된 데이터들을 그들의 인기도를 반영하여 방송할 수 있기 때문에 평균 예상지연시간을 최소화할 수 있다.

Broadcast-based data dissemination has become a widely accepted approach of communication in the mobile computing environment. However, with a large set of data items, the expected delay of receiving a desired data increases due to the sequential nature of the broadcast channel. This paper explores the issue of designing proper data allocation on multiple broadcast channels to reduce this wait time, and proposes a new data allocation scheme named near optimal data allocation(NODA). The proposed scheme first partitions all data items in K group based on the theoretical lower-bound of the average expected delay to determine data items which each broadcast channel has to broadcast. Then, NODA further partitions each group of data items in B groups using extended dynamic programming algorithm to broadcast data items allocated on the same broadcast channel in different frequencies. The proposed scheme is capable of minimizing the average expected delay time since it can broadcast data items allocated on the same channel reflecting their popularities.