• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.5
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• pp.116-124
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• 2016

This paper proposes a medium access control protocol for collision detection and resolution when a large number of sensor nodes transmits data in vehicle. The proposed protocol selects a random collision detection (CD) slot after data transmission, suspends its transmission and senses the channel to check whether a collision occurs by the detection of both energy level and jam signal. The proposed scheme uses multiple CD phases and in each CD phase, colliding stations are filtered and only surviving stations compete again in the next CD phase; thus, the collision resolution probability significantly increases. Simulation results show that the proposed protocol using the multiple CD phases has significantly better throughput than the conventional protocol. In addition, according to the number of CD phases and the number of CD slots per phase, the throughput aspect of the proposed scheme is investigated and the optimal parameters are derived.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.1-12
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• 2002

In the multimedia CDMA mobile communication service, it is required to support various applications, such as voice, video, file transfer, e-mail, and Internet access, with guaranteed QoS. In the mixed traffic environment ,which consists of voice, stream data, and packet data, we analyze the network where preemptive priority is granted to delay-intolerant voice service and a buffer is offered to delay-tolerant stream data service. And, for best-effort packet data service, the access control by transmission permission probability is applied to obtain prominent throughput. To analyze the multimedia CDMA mobile communication system, we build a 2-dimensional markov chain model about prioritized-voice and stream data services and accomplish numerical analysis in combination with packet data traffic based on residual capacity equation.

• Journal of the Korea Convergence Society
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• v.9 no.10
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• pp.29-35
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• 2018

A food waste disposer commonly used in restaurants or homes is a type of machine with an agitator attached. The food waste disposer of the crushing type has a problem that the agitator may be broken if the piping or decomposition filter is blocked. In addition, there is an inconvenience that the user must manually open the cover to check the level in the food waste disposer. To solve these problems, this paper proposes a device that combines basic IoT technology with food waste disposer. The proposed device additionally designs and implement a real-time monitor processor and an automatic control processor inside the existing food waste disposer. The proposed food waste disposer allows the user to monitor the inside of the device using the smartphone. In addition, when the food is filled up to a certain position in the food waste disposer, it automatically stops and alarms. Using the proposed system, the user can conveniently check the inside of the food waste disposer, which has the advantage of preventing malfunctions in advance and reducing the probability of malfunction.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.48-55
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• 2015

This paper studies how to solve a problem caused by M2M terminals sending a few data based on $3^{rd}$ Generation Partnership Project(3GPP) Long Term Evolution-Advanced(LTE-A) system and then it is analyzed, proposed, and introduced into the techniques. Especially, it is introduced solution for the lack of Random Access Channel and an increasing number of latency caused by countless M2M devices. It is proposed the technology for M2M grouping as well as allowable access probability according to user type. As it decreases the number of terminal by grouping M2M devices to try random access at PRACH, it can be reduced collision between Cellular users and M2M devices. So, it is proved that the proposed mechanism can solve the increasing average latency of random access on system coexisting Cellular users and M2M devices through simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.1057-1064
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• 2007

Cognitive radio(CR) technique which utilizes empty frequency bands allocated to private business but not being used temporally has been researched. According to the standard, CR users detect the primary user using the same channel, CR users should move to the another channel to guarantee the primary user's decodability. Thus, CR systems cannot use the same channel and support the CR user's QoS(Quality of Service) during the channel moving time. In this paper, we propose a radio resource sharing method that CR basestation controls the transmission power with the primary user's SNR(Signal to Noise Ratio) to increase the spectral efficiency of area and to minimize the outage of CR users. In addition, computer simulation demonstrates show that the proposed method improved spectral efficiency of area and decreased outage probability of CR users.

• Journal of IKEEE
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• v.24 no.1
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• pp.147-153
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• 2020

Conventional lane detection algorithms have problems in that the detection rate is lowered in road environments having a large change in curvature and illumination. The probabilistic Hough transform method has low lane detection rate since it exploits edges and restrictive angles. On the other hand, the method using a sliding window can detect a curved lane as the lane is detected by dividing the image into windows. However, the detection rate of this method is affected by road slopes because it uses affine transformation. In order to detect lanes robustly and avoid obstacles, we propose driving assist system using semantic segmentation based on deep learning. The architecture for segmentation is SegNet based on VGG-16. The semantic image segmentation feature can be used to calculate safety space and predict collisions so that we control a vehicle using adaptive-MPC to avoid objects and keep lanes. Simulation results with CARLA show that the proposed algorithm detects lanes robustly and avoids unknown obstacles in front of vehicle.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3B
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• pp.226-236
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• 2002

In this paper, we present the 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 first describe two types of traffic channel block assignments for utilizing the traffic channel efficiently; the partially dedicated and partially shared channel (PDPSC) assignment and the completely shared channel (CSC) assignment. The former is that some traffic channel block is completely assigned to each traffic type and the other blocks are shared with some traffic type. The latter is that all traffic channel blocks are completely shared with all traffic types. Further, for efficiently assigning, releasing, and managing the channel resource, we present the traffic channel management method which consists of the block and task management step. Through numerical examples, we evaluate the blocking probability and the mean number of required search for fading the available channel when applying our proposed channel block assignment and resource management methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1B
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• pp.11-17
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• 2003

In this paper, we presented the dynamic random access channel allocation method under the priority based scheduling policy in order to improve the system performance of HIPERLAN/2 standardized by ETSI According to the scheduling policy, AP scheduler primarily allocates the resource to the collision MT This scheduling policy bring about decreasing the transmission delay of collision MT Dynamic RCH(random access channel) allocation method decreases the collision probability by increasing the number of RCH slots in case of low traffic. While it increases the maximum throughput by increasing the number of the data transmission slots in case of high traffic Therefore dynamic allocation method of RCH slots decreases the scheduling delay and increases the throughput When we evaluate the performance of presented method based on standards, we saw that the presented method improve the performance of the MAC protocol in terms of throughput and transmission delay.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.8
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• pp.30-41
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• 2001

In this paper, the architecture of Dynamic GSMP V3(General Switch Management Protocol Version 3), an open interface protocol with resource management functions for efficient IP service on ATM over MPLS, is proposed and implemented in hardware. And we compare and analyze the proposed GSMP with the GSMP under standardization process in terms of CLR (Cell Loss Rate). We design the Slave block of the Dynamic GSMP V3 using SAM-SUNG SoG $0.5{\mu}m$ process, which performs functions for switch connection control in the ATM Switch. In order to compare difference performanaces between the proposed method and the conventional one, we conducts simulations using the minimum buffer search algorithm with random cell generation. The exponential results show that the proposed method leads to performance enhancement in CLR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.189-197
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• 2016

Mobile ad-hoc networks (MANETs) experience frequent link disconnections due to non-uniform node distribution and mobility. Thus, end-to-end path establishment-based routing protocols cause frequent transmission failures in MANETs, resulting in heavy control messages for path reestablishment. While location-based MANET routing protocols, such as Greedy Perimeter Stateless Routing (GPSR), use location information to forward messages in a hop-by-hop routing fashion without an end-to-end path establishment procedure, such protocols encounter communication void problems when message forwarding to the next hop fails due to the absence of a relay node. Therefore, to solve this problem, this paper proposes a Delay Tolerant-GPSR (DT-GPSR) protocol, which combines Delay Tolerant Networking (DTN) technology with the GPSR protocol. The performance of DT-GPSR is compared with the performances of the original GPSR and PRoPHET routing protocols through simulation using NS-2. The simulation results confirm that DT-GPSR outperforms GPSR and PRoPHET in terms of the message delivery ratio and message delivery delay.