• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.40-44
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• 2010

opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. A dynamical sensing range as a important parameter introduced to maintain the our protocol performance. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.3
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• pp.148-159
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• 2013

An analysis of the throughput and stability region of random access systems is currently of interest in research and industry. This study evaluated the performance of a multiuser random access channel with a retransmission gain. The channel was composed of a media access control (MAC) determined by the transmission probabilities and a multiuser communication channel characterized by the packet reception probabilities as functions of the number of packet transmissions and the collision status. The analysis began with an illustrative two-user channel, and was extended to a general multiuser channel. For the two-user channel, a sufficient condition was derived, under which the maximum throughput was achieved with a control-free MAC. For the channel with retransmission gain, the maximum steady throughput was obtained in a closed form. The condition under which the random access channel can acquire retransmission gain was also obtained. The stability region of the general random access channel was derived. These results include those of the well-known orthogonal channel, collision channel and slotted Aloha channel with packet reception as a special instance. The analytical and numerical results showed that exploiting the retransmission gain can increase the throughput significantly and expand the stability region of the random access channel. The analytical results predicted the performance in the simulations quite well.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1080-1082
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• 2016

In a multi-hop CR (Cognitive Radio) network, each node find a path to destination node through several links. If links have the same frequency channel, there can be a serious interference among the links and it can reduce the network capacity. In multi-channel CR networks, each channel has different capacity according to the inter-link interference, and each channel has different traffic properties of primary users. In this paper, we propose channel scheduling scheme to minimize channel interferences and collision with primary users. Simulation results show the improvement of channel capacity and collision rate with primary users.

• Journal of IKEEE
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• v.23 no.1
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• pp.302-305
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• 2019

Non-orthogonal multiple access (NOMA) has been considered for the fifth generation (5G) mobile networks to provide high system capacity and low latency. We calculate the channel capacity for the weak channel user in NOMA and the channel capacity region for NOMA. In this paper, Gaussian mixture channel is compared to the additive white Gaussian noise (AWGN) channel. Gaussian mixture channel is modeled when we assume the practical signal modulation for the inter user interference, such as the binary phase shift keying (BPSK) modulation. It is shown that the channel capacity with BPSK inter user interference is better than that with Gaussian inter user interference. We also show that the channel capacity region with BPSK inter user interference is larger than that with Gaussian inter user interference. As a result, NOMA could perform better in the practical environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1136-1145
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• 1993

The channel capacities of various lading channels are calculated and compared with that of Gaussian noise channel to find out the decrements of channel capacity according to each fading environment. As a result, it is confirmed that the channel capacities in Rician and m-distribution fading channels approach to that of Gaussian noise channel as direct-to-indirect power ratio in Rician fading channel and fading index m in m-distribution fading channel increases respectively. And the difference between two channel capacities of Gaussian noise channel and each fading channel which is dependent on carrier-to-noise power ratio (CNR) is found. Also the improvement of channel capacity of Rayleigh fading channel by introducing two-branch diversities is obtained. For diversity reception, predetection maximal-ratio and postdetection selective combining techniques are adopted. The results show that the improvement of channel capacity by predetection maximal-ratio combining diversity is superior to the postdetection selective combining diversitiy regardless of correlation coefficient between two diversity branches in Raylelgh fading channel. The best improvement is achieved when two branches are noncorrelative in both two diversify techniques and as correlation coefficient of two diversity branches is smaller, the improvement of channel capacity is greater.

• Asia Marketing Journal
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• v.15 no.2
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• pp.29-47
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• 2013

Distribution channel decisions involve long-term commitments with other firms that are very difficult to change or replace. In particular, marketing channel decisions in emerging markets are much more complicated due to unfamiliar conditions and problems such as lack of market data and distribution systems. Therefore, when a company considers changing or introducing a marketing channel in an area, it is much more difficult to judge its effectiveness in an emerging market than in a developed market. In this study, we investigate the development process of a new direct marketing channel of Hongfu Fertilizer Company (hereafter Hongfu), a medium-sized Chinese fertilizer manufacturer, and propose an approach to test the feasibility of this new marketing channel in the Chinese rural market. We measure the effectiveness of Hongfu's new marketing channel from two perspectives: i) from customers' perspective through direct responses of farmers, which showed that a new channel can increase the convenience and lower the purchasing costs for the farmers, and ii) from the company's perspective, by calculating the incremental profit of the company using the expansion factor (T/Q) method, which suggested that the execution of Hongfu's strategy to expand a new marketing channel will result in an increase in profits. The results of this study contribute to the development of a methodology to test the feasibility of a new direct marketing channel in the emerging markets such as the Chinese rural market. Traditional and indirect distribution channels in emerging markets are generally not very efficient and difficult to change. Especially, in emerging markets, like the Chinese rural market, the methods of testing channel feasibility must be different from that of developed markets. Considering market situations, market experiments can be more effective then systematic market surveys in testing channel feasibility in emerging markets. This study implies that managers must learn to cope with a transition from the traditional marketing channels in emerging markets. With the development in farmers' understanding of marketing concept, the transition from traditional marketing channel is unavoidable for all firms. Farmers in China are generally very conservative, however, their buying behaviors are changing. Therefore, fertilizer companies should try to adjust in accordance with farmers' demand characteristics that the efforts to meet the economic needs of farmers with new marketing channels as well as trust building are critical in the near future.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.243-248
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• 2021

Although many different types of covert channels have been suggested in the literature, there are little work in directly applying game theory to building up covert channel. This is because researchers have mainly focused on tailoring game theory for covert channel analysis, identification, and covert channel problem solving. Unlike typical adaptation of game theory to covert channel, we show that game theory can be utilized to establish a new type of covert channel in IoT devices. More specifically, we propose a covert channel that can be constructed by utilizing the Nash Equilibrium with sensor data collected from IoT devices. For covert channel construction, we set random seed to the value of sensor data and make payoff from random number created by running pseudo random number generator with the configured random seed. We generate I × J (I ≥ 2, J ≥ 2) matrix game with these generated payoffs and attempt to obtain the Nash Equilibrium. Covert channel construction method is distinctly determined in accordance with whether or not to acquire the Nash Equilibrium.

• The Research Journal of the Costume Culture
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• v.27 no.2
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• pp.98-108
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• 2019

With the expansion of various distribution channels in online and offline stores, TV, and mobile, consumers now have more information search and retail selection channels to choose from than ever before. Major retailers now use multi- and omni-channel strategies. This study focused on cross-channel consumption, which involves the use of different information search and purchase channels. Using cross-channel consumption, consumers can search for information online and then make purchases offline and vice versa. The purpose of this study was to examine the relationship between channel strategies and other consumer variables, and the study also assessed the effect of product type. To conduct this empirical study, the researchers developed a consumer questionnaire concerning three consumer channel strategies-on-on, cross, and off-off-and four product categories-clothing, cosmetics, books, and electronics. The results indicated that gender and marital status did not influence consumer channel strategies, but that age did have a significant influence. The analysis showed that consumers in their 40s preferred the cross channel strategy, perceiving it to be effective, satisfactory, and rewarding. Compared to other products, clothing products showed higher levels of cross channel strategies. Consumers indicated that they prefer searching for information online and then purchasing clothing offline. Overall, clothing products generated higher levels of channel satisfaction and channel switch intentions. Cross-channel clothing shoppers reported effective information retrieval times but longer delivery times.

• IE interfaces
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• v.16 no.3
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• pp.311-321
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• 2003

We propose the improved channel assignment and management methods for an efficient use of traffic channel resource for supporting 12.2 Kbps, 64 Kbps, and 384 Kbps traffic with the different quality of service(QoS) in the radio network controller(RNC) in asynchronous IMT-2000 system. We consider two types of traffic channel block assignments for utilizing the traffic channel efficiently; the Completely Shared(CS) channel assignment and the Partially Dedicated and Partially Shared(PDPS) channel assignment. The former is that all traffic channel blocks are completely shared with all traffic types. The latter is that some traffic channel block is independently assigned to each traffic type and the other blocks are completely shared with some traffic type. We also propose the traffic channel management method which consists of the block and task management step, for efficiently assigning, releasing, and managing the channel resource. Finally, we evaluate the performance through various numerical examples when applying our proposed channel block assignment and resource management methods.

• Journal of information and communication convergence engineering
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• v.8 no.3
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• pp.273-276
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• 2010

Opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.