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Papers - Sasase, Iwao

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Proportional data rate fairness resource allocation for　MIMO-OFDM multiple access channel by considering the correlation effect of line of sight and non line of sight channel conditions

Maung Sann Maw and Iwao Sasase

IEICE Trans. on Communications E95-B （ 7 ） 2414-2423 2012.07

Research paper (scientific journal), Joint Work, Accepted

Modeling enhancements in DSR, FSR, OLSR under mobility and scalability constraints in VANETs

Nadeem Javaid, Ayesha Bibi, Akmal Javaid, Safdar H. Bouk and Iwao Sasase

3rd IEEE International Workshop on Smart Communications in Network Technologies, ICC2012 ('ICC'12 WS -SaCoNet-III') （IEEE) 2012.06

Research paper (scientific journal), Joint Work, Accepted

Modeling enhancements in DSR, FSR, OLSR under mobility and scalability constraints in VANETs

Nadeem Javaid, Ayesha Bibi, Akmal Javaid, Safdar H. Bouk and Iwao Sasase

3rd IEEE International Workshop on Smart Communications in Network Technologies, ICC2012 ('ICC'12 WS -SaCoNet-III' 2012.06

Research paper (scientific journal), Joint Work, Accepted

Frequent topological changes due to high speed is one of the main issues in Vehicular Ad-hoc NETworks (VANETs). In this paper, we model transmission probabilities of 802.11p for VANETs and effect of these probabilities on average transmission time. To evaluate the performance of routing protocols in VANETs, we select three routing protocols; Dynamic Source Routing (DSR), Fish-eye State Routing (FSR) and Optimized Link State Routing (OLSR). Framework of these selected routing protocols with respect to their packet cost is also a part of this work. Moreover, the chosen protocols are enhanced to obtain efficient behavior by modifying their default parameters. Simulation work is done in NS-2 for evaluation and comparison of original protocols with modified ones. For this comparison, we choose three performance metrics; throughput, End-to-End Delay (E2ED) and Normalized Routing Load (NRL) in varying mobilities and scalabilities. Finally, we deduce that modified DSR (DSR-mod) outperforms other protocols by achieving 16% more packet delivery for all scalabilities and 28% more throughput.

Dijkstra-Based Higher Capacity Route Selection Algorithm Using Bounded Length and State Change for Automobiles

I-Te Lin, Dilip Sarkar, Tutomu Murase and Iwao Sasase

IEEE Vehicular Technology Conference 2012-Spring 2012.05

Research paper (scientific journal), Joint Work, Accepted

Dijkstra-Based higher capacity route selection algorithm using bounded length and state change for automobiles

I-Te Lin, Dilip Sarkar, Tutomu Murase and Iwao Sasase

IEEE Vehicular Technology Conference 2012-Spring 2012.05

Research paper (scientific journal), Joint Work, Accepted

In general, automobiles travel from the origin to the destination using a shortest route. However, the shortest route may not be a highest wireless connection-capacity route, because of availability of wireless services (base station and access points etc.) along the route. To the best of our knowledge, currently no algorithm exists for selecting a route that maximizes wireless connection-capacity, while keeping route length shortest and close to shortest. In this paper, we propose two modified version of Dijkstra route selection algorithms: one for selecting a maximum connection capacity shortest route, and the other is for discovering higher wireless connection-capacity routes; the length of the route could be larger than a shortest route, but no larger than predetermined bound. The second proposed algorithm exploits the state change of the intersection to broaden the search range of possible routes. Results from our extensive simulation for a Manhattan-street type grid network with the heterogeneous IEEE 802.11a wireless access, show that for a 50% increase in route length and 15 Access Points (APs), the proposed algorithm can increases wireless connection-capacity by 35.67% and 31.27% compared to the shortest and random route selection algorithms, respectively.

Reduced complexity scheme for MIMO receiver with combined ZF-OSIC and ML detection

Maung Sann Maw, Hajime Suzuki and Iwao Sasase

2012 IEEE Symposium on Computer and Informatics (ISCI 2012) 2012.03

Research paper (scientific journal), Joint Work, Accepted

Reduced complexity scheme for MIMO receiver with combined ZF-OSIC and ML detection

Maung Sann Maw, Hajime Suzuki and Iwao Sasase

2012 IEEE Symposium on Computer and Informatics (ISCI 2012) 2012.03

Research paper (scientific journal), Joint Work, Accepted

Wireless system capacity can be increased enormously by using multiple antennas at transmitter and receiver sides in the system. Among them, maximum likelihood (ML) receiver is an optimal receiver, but it is difficult to implement due to high complexity arising from exhaustive
searches over all candidate vector symbols. On the other hand, zero forcing ordered successive interference cancellation (ZF-OSIC) receiver can reduce the complexity greatly although its performance is less than ML receiver. Performance of ZF-OSIC receiver is seriously affected by the lower SNR layers. Therefore, in our proposed detection scheme, we will choose the optimal number of transmit antennas in the high SNR transmit layers, to be detected by the ZF-OSIC scheme and the remaining transmit antennas in the low SNR trasnmit layers will be detected by ML scheme to give the better BER performance for the spatial multiplexing MIMO system. Simulated results show that the complexity of the proposed system is less than that of conventional ZF-OSIC receiver under the same or better BER performance condition. The processing time of proposed method is significantly reduced when compared with conventional ML detection scheme as well as ZF-OSIC detection scheme.

DDoS攻撃に対し排他的論理和と確率的Marking方式を用いることでルータへの負荷分散を実現するIP Traceback

SASASE IWAO

情報処理学会論文誌 53 （ 2 ） 795-804 2012.02

Research paper (scientific journal), Joint Work, Accepted

DoS 攻撃や DDoS 攻撃に対し，その発信元を特定するIP トレースバックは重要な技術である．これまで，マーキング方式やロギング方式が個別に提案されてきたが，マーキング方式ではトレースバックのために大量の攻撃パケットの回収が必要であるという課題があり，またロギング方式では全ての通過パケットのハッシュ値を保持するためルータへの負荷が増大するという課題がある．近年，２つの方式の課題を補う HIT(Hybrid IP Traceback) 方式が提案された．HIT方式ではマーキングとロギングを交互に行うことでロギング回数を従来と比較し半分に低減しているが，全ての通過パケットに対して処理を行わなければならない課題や，DDoS攻撃において被害ホスト近傍のルータへ大きな負荷がかかるといった課題がある．そこで本論文では， DDoS 攻撃に対するトレースバックにおいて， 95% 以上の高いトレースバック成功率を達成しつつルータへの負荷を低減・分散するために，排他的論理和と確率的パケットマーキングを用いたトレースバック方式を提案する．排他的論理和を用いることで 2 つのルータの ID を 1 つにまとめることができ，ロギングの回数を低減することが可能となる．また， DDoS 攻撃において攻撃パケットは大量に送信されてくるという特徴と被害ホスト近傍に攻撃パケットが集中するということを考慮して，全ての通過パケットではなく確率的に選択したパケットに対して 1 度のみ処理を行う．これにより，ルータへの負荷を低減することが可能となる．計算機シミュレーションにより各方式におけるトレースバック成功率とパケット処理率，またパケット処理回数の評価を行い，高いトレースバック成功率を達成しつつルータへの負荷を低減・分散可能な提案方式の有効性を示す．

Grid-based routing protocol using cell rotation to reduce packets latency and energy consumption in wireless sensor networks

Hidetoshi Kajikawa, I-Te Lin and Iwao Sasase

IEEE 6th Consumer Communications & Networking Conference(CCNC'2012), 3rd International Research Student Workshop 2012.01

Research paper (scientific journal), Joint Work, Accepted

We propose a grid-based routing protocol which divides the network area for large side length of square cells by using cell rotation to reduce the number of relay nodes between the source node and the mobile sink. The proposed scheme divides each cell into multiple sub-cells, and assumes one or two sub-cells to be active-cells. Then, the proposed scheme confines the existing area of active nodes to each active-cell. Because the maximum transmission range is a fixed value, the side length of square cells can be enlarged by confining the area where the active node exist in each cell. Therefore, the proposed scheme decreases the number of relay nodes between the source node and the mobile sink due to the large cells divided, and reduces the data packets delivery latency and the energy consumption. The proposed scheme introduces three types of dividing method, which assume 2-, 4-, and 6-division method. The high numbers of division method improves each characteristic values due to expanding the side length of square cells under the condition of high density of sensor nodes. The simulation results show that the proposed scheme improves the packets latency and the energy consumption efficiency.

A primary traffic based multihop routing nalgorithm using cooperative transmission in cognitive radio ad hoc networks

I-Te Lin and Iwao Sasase

IEEE 6th Consumer Communications & Networking Conference(CCNC'2012), 2nd International Workshop on Densely Connected Networks 2012.01

Research paper (scientific journal), Joint Work, Accepted

We propose a primary traffic based multihop routing with the cooperative transmission(PTBMR-CT) algorithm that enlarges the hop transmission distances to reduce the number of hops of the route from the cognitive source (CS) to the cognitive destination (CD). In each hop, from the cognitive nodes in a specified area depending on the status of the primary traffic, the cognitive node that is farthest away from the cognitive sender is selected as the cognitive receiver. However, when the primary source (PS) is transmitting the data to the primary destination (PD), another cognitive node is also selected to be the cognitive receiver for the cooperative transmission from the cognitive nodes that are in a specified area. The cooperative transmission is performed if the PS still transmits the data to the PD when the cognitive receiver of the next hop is being searched. The simulation results show that the average number of hops is reduced by the PTBMR-CT compared to the conventional primary traffic based farthest neighbor routing (PTBFNR), and the conventional PTBFNR is outperformed by the PTBMR-CT in terms of the average end-to-end reliability, the average end-to-end throughput, and the average required transmission power of transmitting the data from the CS to the CD.

Efficient solution to decrease the effect of DoS attack against IP address ownership proof in mobile IPv6

Kentaroh Toyoda, Yuta Kamiguchi, Shinichiro Inoue and Iwao Sasase

2011 IEEE International Symposium on Personal, Indoor, and Mobile Radio Communications(PIMRC'11) 2011.09

Research paper (scientific journal), Joint Work, Accepted

In Mobile IPv6(MIPv6), the Mobile Node(MN) communicating with the Correspondent Node(CN) cannot prove ownership of the claimed IP address. If a malicious node impersonates victim's IP address, it could hijack the session or forward packets to non-existing destination or other nodes. Currently, in order for the MN to prove ownership of its own IP address, it is considered using Feige-Fiat-Shamir (FFS) Identification Scheme cite{FFS}. However, there is one serious problem. In FFS Identification Scheme, the CN has to verify all of the Binding Update requests, and this leads to DoS(Denial of Service) attack. This paper shows a method which mitigates the effect of DoS attack by making Challenge twice in one transaction. We make the first Challenge easy to verify it to exclude the malicious nodes and the second one much more difficult than the first one to avoid impersonation. This method can efficiently exclude malicious nodes which do not have proper IP addresses by verifying the first Challenge. Furthermore, by making the Challenge twice, our scheme can decrease the probability of impersonation over the conventional scheme for almost the same amount of calculation. By computer simulations, we show that the proposed scheme is efficient to decrease the effect of the DoS attack and the probability of impersonation compared to the conventional scheme.

Asynchronous receiver-initiated MAC protocol with the stair-like sleep in wireless sensor networks

Takahiro Wada I-Te Lin and Iwao Sasase

2011 IEEE International Symposium on Personal, Indoor, and Mobile Radio Communications(PIMRC'11) 2011.09

Research paper (scientific journal), Joint Work, Accepted

We propose the asynchronous receiver-initiated MAC protocol with the stair-like sleep that each node reduces its own sleep time by the sleep-change-rate depending on the number of hops from the source to the sink in wireless sensor networks (WSNs). Using the stair-like sleep, our protocol achieves the high delivery ratio, the low packet delay, and the high energy efficiency due to the reduction of the idle listening time. Our protocol can formulate the upper bound of the idle listening time because of the feature that the sleep time decreases in the geometric progression, and the reduction of the idle listening time is obtained by using the stair-like sleep. In our proposed scheme, the sink calculates the sleep change rate based on the number of hops from the source to the sink. By using the control packets which have the role of ACK, our proposed protocol can achieve the stair-like sleep by no additional control packets. In addition, even in the network condition that multi-targets are detected, and hops to the sink are changed frequently, our proposed protocol can change the sleep change rate adaptively because the sink can always obtain the number of hops from the source to the sink. Simulation results show that the proposed protocol can improve the performances in the packet delivery ratio, the packet delay, and the energy efficiency compared to the conventional receiver-initiated MAC (RI-MAC) protocol.

A duty cycle MAC protocol with energy consumption reduction by decreasing the number of hops in wireless sensor networks," 8th IEEE Asia Pacific Wireless Communication Symposium

Tatsuya Koizumi, Shinji Kano and Iwao Sasase

8th IEEE Asia Pacific Wireless Communication Symposium 2011.08

Research paper (conference, symposium, etc.), Joint Work, Accepted

Light-Weight energy efficiency Media Access Control (LWMAC) is an asynchronous duty cycle MAC protocol to shorten the preamble length by selecting the node which is changed to be in active mode first during the preamble as a next hop node without selecting it in advance, and then reduces energy consumption in wireless sensor networks. However, LWMAC may increase the number of hops because it doesn't consider the distance from a source node to a next hop node. Therefore, when a source node selects a node which is far to a sink node as a next hop node, energy consumption cannot be reduced. In this paper, we propose a duty cycle MAC protocol that decreases the number of hops and reduces energy consumption by selecting a node that is closer to a sink node as a next hop node when more than two candidate nodes change to be in active mode until the end of preamble whose length is same in LWMAC. By the simulation, we evaluate the average number of hops of LWMAC and the proposed scheme. The simulation results show that the proposed scheme reduces the energy consumption by decreasing the average number of hops.

A load-distributed IP traceback by using exclusive-OR and brobabilistic packet marking for DDoS attacks

Shinichiro Inoue, Shinji Kano, Masakuni Ishii and Iwao Sasase

8th IEEE Asia Pacific Wireless Communication Symposium 2011.08

Research paper (conference, symposium, etc.), Joint Work, Accepted

Tracing IP packets back to their origins is an important scheme to defend against Denial Of Service(DoS) and distributed DoS (DDoS) attacks. Mainly, two kinds of IP Traceback schemes have been proposed. One is a packet marking scheme that each router marks their ID into packets. The other is a packet logging scheme that each router logs the digest of the forwarded packets. Recently, hybrid IP Traceback scheme, which makes up for shortcomings of above two schemes, has been proposed. In this hybrid scheme, the overhead on routers can be reduced compared to the conventional scheme. However, due to marking and logging for DDoS attacks, the hybrid scheme still causes much overhead, and routers near victim server have lots of burden. In this paper, we propose an IP Traceback scheme which uses exclusive-or and probabilistic packet marking to reduce burden on routers while achieving high traceback success rate compared to the conventional schemes. The proposed scheme uses not only packet marking and packet logging but also exclusive-or. Because two routers ID can be combined by using exclusive-or, the number of routers which log packets decreases. Furthermore, considering that huge number of packets gather around routers near a victim server for DDoS attacks, each router makes its job(marking, logging, exclusive-or) probabilistically and only once. By taking this scheme, the closer routers are to a victim server, the smaller probability that routers make its job is, and it can reduce burden on each router. By computer simulation, we evaluate a traceback success rate, a probability that each router make its job to forwarding packets and packet numbers that each router makes its job. We show that our proposed scheme can achieve high traceback success rate while reducing huge burden on routers compared to conventional schemes.

Efficient resource allocation for multiuser MIMO-OFDM uplink system to guarantee the proportional data rate fairness among users in a system

Maung Sann Maw and Iwao Sasase

1st International Symposium on Access Spaces (IEEE-ISAS2011) 2011.06

Research paper (conference, symposium, etc.), Joint Work, Accepted

The performance of multi-user MIMO-OFDM Multiple Access Channel

(MIMO-OFDM-MAC) Uplink systems can be significantly increased by

using adaptive transmission and efficient resource-allocation scheme

in the system. In the MIMO-OFDM-MAC scenario, the base station

decides centrally on the optimal bit loading and subcarrier

allocation as well as transmit antenna selection from multiple users

based on channel state information (CSI) in the system. There have a

lot of papers which have done on the resource allocation in MIMO-OFDM

system. But most of them consider in MIMO-OFDM downlink and very few

papers consider to give the fairness among users. Moreover, there has

no paper which considers to give the proportional data rate fairness

among user in the uplink MIMO-OFDM-MAC system. In this paper,

resource allocation for spatial and spectral dimension and adaptive

bit loading scheme is proposed to improve the total system capacity

under the constraint of total transmit power and target bit error

rate (BER) for each user and proportional data rate fairness among

users in the uplink MIMO-OFDM-MAC system.

A multihop cooperative routing algorithm for minimizing the number of hops in spectrum sharing networks

I-Te Lin and Iwao Sasase

6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications(CrownCom2011) 2011.06

Research paper (conference, symposium, etc.), Joint Work, Accepted

We propose a novel multihop cooperative routing (MCR) algorithm that extends the lengths of the x axis projections of
the hop distances and finds the multihop route that minimizes the number of hops in spectrum sharing networks. At each hop
except the last one, firstly, the cognitive relay that is nearest from the cognitive sender is selected. If the participation of the
selected cognitive relay can not satisfy the QoS requirement of the cognitive transmission, among the cognitive receiver candidates
that satisfy the QoS requirement of the cognitive transmission, the one whose x coordinate has the largest difference from that of the
cognitive relay is selected as the cognitive receiver. At the last hop, if the cognitive relay is available, the cooperative transmission
is performed. Otherwise, the direct transmission is performed. Simulation results show that the MCR reduces the average
number of hops compared to the FNR and outperfoms the FNR in terms of the average end-to-end reliability, the average end-toend
throughput, and the average required transmission power.

Statistical analysis of quantization noise in an end-to-end OFDM link

Maduranga Liyanage　SASASE IWAO

IEICE Transactions on Communications E94-B （ 5 ） 2011.05

Research paper (conference, symposium, etc.), Joint Work, Accepted

Target detection with MSN algorithm for the bistatic radar using digital terrestrial broadcasting signals

Junji Asada and SASASE IWAO

IEICE Trans. on Communications E94-B （ 2 ） 515-525 2011.02

Research paper (conference, symposium, etc.), Joint Work, Accepted

Distributed ad hoc cooperative routing in cluster-based multihop networks

I-Te Lin, SASASE IWAO

IEICE Transactions on Communications E94-B （ 2 ） 444-454 2011.02

Research paper (conference, symposium, etc.), Joint Work, Accepted

Broadcast traffic queueing in OFDMA systems for spectrum efficiency and improved QoS provisioning

Maduranga Liyanage and SASASE IWAO

IEEE Globecom 2010 2010.12

Research paper (conference, symposium, etc.), Joint Work, Accepted

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