Earticle

가시광통신은 기존에 설치된 LED등을 사용하기에 무선통신을 위한 방법 중의 하나이다. 본 논문은 이미지 처리 기술을 이용한 광카메라 통신(OCC: Optical Camera Communications) 기술을 제안한다. LED등은 빠른 속도로 on 및 off를 변경할 능력을 가지고있기에 인간의 눈이 인지할 수 없을 정도로 일정한 조도와 함께 데이터를 전송해야 한다. 하나의 데이터 프레임에서 비트 ‘1’ 및‘0’ 사이의 밝기 불균형에 의해 flickering 문제가 발생한다. Manchester code, 4B6B, 8B10B 및 VPPM과 같은 다양한 Run lengthlimited(RLL) coding 기법이 사용될 수 있지만 LED

Visible Light Communication is one of the promising technologies for wireless communication due to the possibility to useexisting LED lightening infrastructure to transmit data. LED has the ability to turn on and off very fast enough that ourhuman eyes can’t recognize so it can be used to transmit data via visible light along with illumination. But it faces flickerproblem due to the brightness discrepancies between ‘1’ and ‘0’ bit patterns inside a data frame. Various run length limited(RLL) coding scheme like Manchester code, 4B6B, 8B10B or VPPM can be used to solve flickering problem. So we proposepseudo Manchester codding which can transmit data without modifying LED modulator and demodulator circuit as well assolve flickering problem.

RFID 리더의 가장 중요한 기능은 자신의 인식 범위 내에 있는 개별 제품들에 부착된 태그의 고유한 EPC (Electronic Product Code) 코드를 식별하는 것이다. RFID 리더는 무선채널을 통하여 각각의 태그들에 쿼리 메시지 를 전송하고, 태그들은 쿼리 메시지에 응답하여 동시에 자신의 식별코드를 전송하기 때문에 태그 충돌이 발생한다. 태 그 충돌 방지 기법은 RFID 기술이 다양한 산업 분야에 적용되기 위해서 해결되어야하는 핵심적인 기술이다. 본 논문 에서는 충돌비트의 위치 정보를 리더에서 뿐 아니라 태그에서도 이용할 수 있는 개선된 M-ary QT 알고리즘을 제안 하였으며, 태그들로부터의 응답메시지를 분석하여 다수의 쿼리 메시지를 하나의 쿼리 메시지로 통합할 수 있는 기법을 제안하여 M-ary QT 알고리즘의 성능을 향상시켰다. 시뮬레이션 결과 제안된 알고리즘은 기존의 M-ary QT 기법에 비하여 질의-응답 수, 인식 효율, 통신비용 관점에서 매우 성능이 우수함을 보였다.

The most important mission of RFID reader is identify EPC (Electronic Product Code) of RFID tag of products that located within distinguishable range of RFID reader. RFID reader transmits query message to RFID tags through wireless channel and RFID tags send unique EPC to response its query message simultaneously. therefore tag collision occurred frequently. RFID tags collision resolution algorithm required to apply RFID technology to various industries. In this paper, we propose enhanced M-ary algorithm that collision bits location is used by not only RFID reader but also tags. the main feature of the proposed algorithm is that integrate multiple query message of M-ary QT algorithm to the single query message by analyze multiple response messages from tags. the simulation results show that the proposed algorithm give better performance than M-ary QT algorithm in terms of the number of query-response, identification efficiency and communication overhead.

Optical camera communication (OCC) is an extension of Visible Light Communication. Different from traditional visible light communication, optical camera communications is an almost no additional cost technology by taking the advantage of build-in camera in devices. It was became a candidate for communication protocol for IoT. Camera module can be easy attached to IoT device, because it is small and flexible. Furthermore almost smartphone equip one or two camera for both back and font side with high quality and resolution. It can be utilized for receiving the data from LED or positioning. Actually, OCC combines illumination and communication. It can supply communication for special areas or environment where do not allow Radio frequency such as hospital, airplane etc. There are many concept and experiment be proposed. In this paper we proposed utilizing Android smart-phone camera for receiver and introduce new approach in modulation scheme for LED at transmitter. It also show how Manchester coding can be used encode bits while at the same time being successfully decoded by Android smart-phone camera. We introduce new data frame format for easy decoded and can be achieve high bit rate. This format can be easy to adapt to performance limit of Android operator or embedded system.

Radio-frequency identification (RFID) is the wireless non-contact use of radio- frequency electromagnetic fields to transfer data, for the purposes of automatically identifying and tracking tags attached to objects. Most important technical issue in radio frequency identification (RFID) is to correctly and quickly recognize a number of tag IDs in the reader’s communication range. At present, a reasonable solution is the introduction of M-ary QT(Query Tree) to reduce the collision time slots and additional query is used to decrease idle timeslots. In this paper, we proposed a dynamic M-ary QT protocol, which effectively reduces unnecessary query-response cycles by varying ‘m’-bit recognition method. By using Manchester code, we can detect the location of collided bits due to the characteristic of Manchester code. We proposed enhanced tag identification algorithm that utilize feature of Manchester coding to increase efficiency of Tag identification not only in RF- ID reader but also in RF-ID tags. From the simulation results, the proposed scheme significantly outperforms traditional M-ary QT schemes in terms of efficiency and communications overhead, identification time.

The Radio Frequency Identification (RFID) system is a newemerging technology used to identify a tag attached to an object. To make RFID systems practical, the cost of RFIDtags is very important. Further, an interrogator should be able to identify thenumber of tags in the reading range in a short time. The most important technical issue in radio frequency identification (RFID) is to correctly and quickly recognize the number of tag IDs in the reader’s communication range. Unlike the probabilistic RFID tag identification schemes, a query tree(QT)-based protocol guarantees the identification of all the tags, where the distribution of tag IDs is assumed to be uniform. In this paper, we proposed an extended M-ary QT protocol, which effectively reduces unnecessary query-response cycles by using a non-sequential m-bit recognition method. The simulation results show that the proposed scheme significantly outperforms M-ary QT schemes in terms of identification time, efficiency and communications overhead.

최근 활발한 연구가 진행되고 있는 센서 네트워크 시스템은 센서 노드 주변에서 수집된 환경 정보를 베이스로 전달하여 정보를 통합하는 시스템이다. 다양한 환경에 적용하기 위하여 정보 전달에 주로 무선 채널을 활용하는데 기존과 같이 라디오 주파수 채널을 이용하는 경우 센서 노드가 복잡해지고, 도청의 위험성이 존재한다. 본 논문에서는 이러한 단점을 피하기 위해 광(光)채널을 형성하고, 이를 이용하여 데이터를 전송하는 기법을 제안한다.

Greg([Greg]) considered that $$N_k= \sum\limits_{i=1}^k(-1)^{i+1}P_{i,k}(p)N_1^i$$ where the $P_{i,k}$'s were polynomials with positive integer coefficients. In this paper, we will give the equations for $\sum\limits{P_{i,k}$ modulo 3. Using this, if we send a information for elliptic curve to sender, we can make a new checksum method for Manchester coding in IEEE 802.3 or IEEE 802.4.

We compare the performance of a wavelength remodulated wavelength-division-multiplexed passive optical network implemented using Manchester-coded or inverse-return-to-zero (IRZ)-coded signal downstream and non-return-to-zero remodulated signal upstream. We investigate the effects of varying differences between downstream and upstream bit rates on the two coding schemes. When the bit rate ratio of upstream to downstream is less than or equal to 50%, the performance of Manchester coding is better than that of IRZ coding. However, when the bit rate ratio of upstream to downstream is higher than 50%, Manchester code requires appropriate time delay between upstream and downstream signals, whereas IRZ code needs reduced extinction ratio in the downstream signal.