Earticle

본 논문은 USN 무선 네트워크에서 16-QAM 수신 신호의 멀티 홉 중계를 수행하는 경우 적응 신호 처리 알고리즘을 적용한 루프백 간섭 신호의 제거 성능에 관한 것이다. 이를 위하여 USN 환경에서는 노드간의 중계 기능에의해 원거리 스테이션과의 정보 교환이 필요하게되는데, 중계 노드에서는 송신기와 수신기 안테나를 공동 이용하거나 매우 근접하여 위치하므로서 재송신 신호가 수신측으로 궤환되거나, 비선형 소자를 사용하므로서 발생되는 루프백 간섭 신호가 존재하게되므로 한정된 주파수와 전력 자원을 사용하는 USN 시스템의 성능을 크게 저하된다. 이를 개선하여 향상된 시스템 성능 및 멀티홉 성능을 얻기위해 중계 노드의 수신부 전단에서 원하지 않는 루프백 간섭 신호를 제거하기위한 적응 신호 처리 알고리즘의 적용이 필요하게된다. 적응 신호 처리를 위해서는 먼저 스펙트럼 효율이 우수한 16-QAM 신호를 대상으로하여 수렴 특성이 우수하고 H/W 로 구현할 때 발생되는 유한장 문제점을 해결할 수 있는 QR-Array RLS 알고리즘을 사용하였으며, 루프백 간섭 신호의 제거 성능으로 수신 신호 성상도 및 learning curve에서 기존의 RLS 보다 우월함을 컴퓨터 시뮬레이션을 통해 확인할 수 있었다.

This paper deals with the cancellation performance of loop back interference signal in the case of multihop relay of 16-QAM received signal at the USN radio network. For this, it is necessary to the exchange of information with long distance located station by means of the relay function between the node in the USN environment. In the relay node, the loop-back interference signal which the retransmitting signal is feedback to the receiver side due to the antenna of transmitter and receiver are co-used or very colsely located or using the nonlinear device. Due to this signal, the performance of USN system are degraded which are using the limited resource of frequency and power. For improve this, it is necessary to applying the adaptive signal processing algorithm in order to cancellating the unwanted loop-back interference signal at the frontend of receiver in relaying node, we can get the better system and multi hop performance. In the adaptive signal processing, we considered the 16-QAM signal which has a good spectral efficiency, firstly, than, the QR-Array RLS algorithm was used that has a fairly good convergence property and the solving the finite length problem in the H/W implementation. Finaly, we confirmed that the good elimination performanc was confirmed by computer simulation in the learing cuved and received signal constellation compared to the conventional RLS.

This paper proposes an efficient full-duplex multiple input multiple output (MIMO) relay in wireless multihop networks. The proposed relay consists of a minimum mean square error (MMSE) filter, a decode-and-forward protocol processor, and a modified Alamouti encoder. In consideration of the tradeoff between performance and complexity, the MMSE filtering is presented to suppress the spatial loop interference, and the modified Alamouti encoding is simply added to improve the performance of the destination by intimately collaborating with the relay. Simulation results confirm that the proposed method outperforms the conventional methods at the expense of a reasonable increase in complexity.

This study shows achievable capacity gain from the MMR system. Relay stations are placed along the cell boundary in tiers. We can have as many tiers of relays and as many relays in each tier as we want. A model is developed, which can estimate the system capacity varying the number of relays in each tier and the bandwidths allocated to the BS and the RS. It is shown that maximum capacity increases are 21.5% and 18.9% when we have relays in the first tier only and in the first and the second tiers, respectively.

In this paper, we propose an efficient macrodiversity handover (MDHO) technique for time-division-based interference-limited IEEE 802.16j multihop wireless relay networks. In the proposed MDHO, when the diversity set members of the mobile station (MS) are a base station (BS) and relay station (RS), the MS receives the signal transmitted by the BS in the first phase. During the second phase, it also receives the simultaneous transmissions of the BS and RS. Furthermore, when the diversity set members are two RSs or two BSs, the MS receives only the simultaneous transmissions of the diversity set members. The superiority of the proposed MDHO is validated using analytical and simulation results. The performance analysis metrics are the average downlink (DL) carrier to interference and noise ratio (CINR), the average DL spectral efficiency, and the average service outage probability. Evaluation results show that the proposed MDHO significantly outperforms the conventional MDHO. The CINR gain achieved using the proposed MDHO is 4.71 dB compared to the conventional MDHO.

전쟁을 효과적으로 수행하는 데에 있어서 핵심적인 요소는 필요한 전장정보를 실시간으로 인접부대와 부대원들과 실시간으로 공유하고, 가장 효과적이고 효율적인 결심을 할 수 있도록 도와주는 C4I 체계라고 할 수 있다. 한국군은 새로운 형태의 미래전쟁을 준비하기 위하여 차기 전술통신체계인 TICN을 개발하고 있다. TICN 체계에서 대대급 전투부대의 C4I 체계의 보강을 위해 TICN 체계에는 TMMR이라는 다대역 다기능 무전기를 개발 및 전력화 할 계획이다. TMMR은 산악지형에서 통신 생존성을 극대화하기 위하여 Ad-Hoc 네트워크를 지원함으로써 인접 부대 또는 부대원과의 다중홉 중계 네트워크를 구성할 수 있다. TMMR은 매체 접근 제어(Media Access Control, MAC) 방식으로 IEEE 802.11 표준을 사용하는데, 하지만 이 프로토콜은 다중홉 중계 네트워크에서 트래픽의 양이 증가할 경우 병목현상 및 불공정성 문제를 불러일으킨다. 이는 전투 국면과 같은 데이터의 양이 급격하게 증가하는 상황일 경우 지휘관 또는 지휘자의 중요한 명령이 제대로 전달되지 못하여 전투에 치명적인 피해를 초래할 수 있으며, 또한 통신에 필요한 제어정보, 예를 들어 라우팅 정보 등이 제대로 전달되지 못하여 통신 효율성을 감소시킬 수 있다. 따라서 본 논문에서는 다중홉 중계 네트워크에서 발생할 수 있는 병목현상 및 불공정성 문제를 해결하기 위한 CWmin과 TXOP에 기반한 우선권 기법들을 제안하고, 이 우선권 부여 기법들이 갖는 특징을 면밀하게 분석하고자 한다. 또한 이 우선권 기법들을 이용하여 병목현상 및 불공정성을 해결할 수 있음과 우선권에 적용에 따른 특징을 시뮬레이션 결과를 통하여 증명 및 분석하고자 한다.

In the future warfare, the instant sharing of battlefield information will be crucial factor to win against the enemy. The joint awareness between battle units about the states of friendly forces, enemies, and battlefield environments enables commanders and combatants to make a decision effectively and efficiently within a limited time. To secure continual communications in battlefield environments, the implementation of multihop relay networks must be considered to be applied to C4I system. In multihop relay networks, the most commonly adopted MAC protocol is IEEE 802.11 standard due to its autonomous and distributed manner. However, this standard doesn't work well in multihop relay networks, since there exist bottleneck and unfairness problem caused by the characteristics of IEEE 802.11 allowing nodes to have same opportunities of channel usages stochastically. In this paper, we analyze these two problems and suggest two priority schemes based on CWmin and TXOP respectively to resolve the problems. The simulation results of NS-2 will be given to validate our proposed schemes and discuss the comparison of two priority scheme.

In this paper, we propose an opportunistic data relay scheme in narrowband multihop combat radio networks. Narrowband networks have physical restrictions on high-speed transmission. Furthermore, the topology changes dynamically due to the jamming of the enemy, signal interference between friendly forces, and movement of network entities. Therefore, the traditional relay scheme that collects topology information and calculates a relay path before transmission is unsuitable for such networks. Our proposed scheme does not collect topology information and transmits data opportunistically. The scheme can cause unnecessary data relaying that is not related to data delivery to the destination node. However, for small networks, the effect of increasing network throughput by not gathering topology information is much greater than the effect of reducing throughput by unnecessary data relays. We demonstrate the performance superiority of the proposed scheme through simulation in the worst case of network topology.