• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.12 s.354
• /
• pp.9-15
• /
• 2006

In this paper, signal processing techniques for noncoherent impulse-radio-based UWB (IR-UWB) communication system are proposed to provide system implementation of low power consumption and low complexity. The proposed system adopts a simple modulation technique of OOK (on-oft-keying) and noncoherent signal detection based on signal amplitude. In particular, a technique of a novel high speed digital sampler using a stable, lower reference clock is developed to detect nano-second pulses and recover digital signals from the pulses. Also, a 32 bits Turyn code for data frame synchronization and a convolution code as FEC are applied, respectively. To verify the proposed signal processing techniques for low power, low complexity noncoherent IR-UWB system, the proposed signal processing technique is implemented in FPGA and then a short-range communication system for wireless transmission of high quality MP3 data is designed and tested.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.6
• /
• pp.42-47
• /
• 2008

In this article a novel constant amplitude precoding for impulse UWB system is proposed. According to IEEE 802.15.4a, impulse UWB can be used in indoor localization and sensor data transmission. Most USN(ubiquitous sensor networks) needs multiple access. However impulse UWB system has a limited capability to detect superpositioned signal induced by multiple access. To overcome this problem we have adopted the concept of CAMC(Constant Amplitude Multi-Code) deviced by Wada and Kim. The proposed system consists of systematic constant amplitude precoding and LDPC decoding. And this system shows a good BER performance in computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.11A
• /
• pp.1682-1690
• /
• 2000

최근들어 초광대역 시간 도약 임펄스 무선 전송(ultra wideband time hopping impulse radio; 이하 IR) 기술이 실내 무선 LAN이나 군용 무선 통신 시스템 등을위한 새로운대역 확산 전송 방식으로서 큰 관심을 모으고 있다 IR 시스템은 1(nsec) 이하의 매우 짧은 펄스폭의 펄스 위치 변조(pulse position modulation)된 가우시안 모노사이클 펄스열을 이용함으로서 매우작은 크기 의수 GHz에 이르는 초광대역 스펙트럼을 가지며 기존의 통신 시스템에 거의 간섭을 미치지 않으면서 사용 가능하다. 본 논문에서는 IR 시스템에 M진 (M-ary) PPM 방식을 적용하는 경우의 성능을 평가하였다. 특시 의사 잡음 부호 발생기와 10진 변환기(decimator)로 구성된 시간 도약 패턴을 사용하여 다원 접속 간섭이 배제되는 부가성 백색 가우시안 잡음 채널 하의 동기식(synchronous) IR 시스템에서, 심벌 수, M, 가우시안 모노사이클 펄스 폭 $\tau$$_{p}$, PPM에서 펄스 간 간격$\delta$, 펄스 반복 횟수 N$_{s}$ 등과 같은 다양한 시스템 파라미터의 조합에 따른 성능 변화를 모의 실험을 통해 확인하였으며, 이러한 결과를 통해 비트 오율, 시스템 복잡도 및 전송율 등의 사양에 따라 적합한 M 진 PPM IR 시스템의 구성 방안에 대한 근거를 제공하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.12
• /
• pp.1765-1767
• /
• 2016

Non-coherent UWB receivers are promising due to the low hardware complexity while the coherent receiver such as the rake receiver requires the complex hardware to estimate channel characteristics and get the synchronization. In this letter, the block coded modulation scheme as one of the most promising method is enhanced in terms of the performance. The performance enhancement is carried out by the modification of the block structure with unequal frame length for each pulse. Simulation results show that the proposed method has the performance enhancement by the transmission rate or bit error rate.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.3
• /
• pp.1-10
• /
• 2010

Impulse Radio Ultra-wideband (IR-UWB) system employing the short pulse has the tolerable characteristics for the multipath environment. The corresponding transceiver with low power consumption can be simply implemented. On the other hand, in the receiver side, the precise channel estimation is required for the knowledge of essence in channel due to the short period of pulse. The estimated gains and delays in channel are used in the rake receiver. The resulting parameters we search have a strong influence on the performance in the entire system. We introduce that the essential parameters can be obtained more precisely through the preamble in receiver side for the channel estimation and related technologies are presented.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.4C
• /
• pp.358-363
• /
• 2010

In IEEE 802.15.4a IR-UWB (Impulse Radio Ultra Wideband) systems, it is crucial to acquire initial carrier/timing synchronization and estimate channel response by exploiting the SYNC symbols embedded in each packet. On the other hand, it is also crucial to detect the SFD pattern followed by the header and data symbols to reliably extract the information contained in the packet. In this paper, we propose a reliable SFD detection scheme utilizing some surplus SYNC symbols in addition to SFD symbols to improve the SFD detection performance.

• Journal of IKEEE
• /
• v.17 no.2
• /
• pp.176-181
• /
• 2013

This paper presents a CMOS impulse radio ultra-wideband (IR-UWB) receiver implemented using IBM 0.13um CMOS technology for inner/inter-chip wireless interconnection. The IR-UWB receiver is based on the non-coherent architecture which removes the complexity of RF architecture (such as DLL or PLL) and reduces power consumption. The receiver consists of three blocks: a low noise amplifier (LNA) with active balun, a correlator, and a comparator. Simulation results show the die area of the IR-UWB receiver of 0.2mm2, a power gain (S21) of 12.5dB, a noise figure (NF) of 3.05dB, an input return loss (S11) of less than -16.5dB, a conversion gain of 18dB, a NFDSB of 22. The receiver exhibits a third order intercept point (IIP3) of -1.3dBm and consumes 22.9mW of power on the 1.4V power supply.

• Journal of Communications and Networks
• /
• v.14 no.5
• /
• pp.501-509
• /
• 2012

This paper proposes a joint timing synchronization, channel estimation, and data detection for the impulse radio ultra-wideband systems. The proposed timing synchronizer consists of coarse and fine timing estimation. The synchronizer discovers synchronization points in two stages and performs adaptive threshold based on the maximum pulse averaging and maximum (MAX-PA) method for more precise synchronization. Then, iterative channel estimation is performed based on the discovered synchronization points, and data are detected using the selective rake (S-RAKE) detector employing maximal ratio combining. The proposed synchronizer produces two signals-the start signal for channel estimation and the start signal for start frame delimiter (SFD) detection that detects the packet synchronization signal. With the proposed synchronization, channel estimation, and SFD detection, an S-RAKE receiver with binary pulse position modulation binary phase-shift keying modulation was constructed. In addition, an IEEE 802.15.4a channel model was used for performance comparison. The comparison results show that the constructed receiver yields high performance close to perfect synchronization.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.3A
• /
• pp.205-212
• /
• 2009

A novel channel estimation scheme is proposed for coherent Impulse Radio Ultra Wideband (IR-UWB) system based on IEEE 802.15.4a specification. By extracting and utilizing the information on the frequency synchronization, the proposed channel estimation algorithm improves the receiver performance even under the restricted number of preamble symbols in IEEE 802.15.4a signal format. Simulation results over the IEEE 802.15.4a channel models show the performance gain with the proposed algorithm compared to ordinary channel estimation method.

• Journal of KIISE:Information Networking
• /
• v.36 no.5
• /
• pp.383-388
• /
• 2009

In this paper, we focus on the retransmission following transmission failure in impulse radio ultra wideband (IR-UWB). The reasons of transmission failure are classified and a new 'selfish' retransmission protocol is proposed because time hopping can support multiple transmissions at the same time. Selfish retransmission protocol retransmits packets immediately without any kind of timeout or channel observation. Simulation results show that the proposed protocol improves throughput up to 50% and decreases retransmission delay also up to 70%, compared to a conventional retransmission system in IR-UWB.