Tae-Won Ban

A distributed scheduling with interference-aware power control for ultra-dense networks

Cellular networks are becoming dense due to deployment of small cells and a number of user devices. Such networks are called ultra-dense networks (UDNs). In this paper, we propose a novel distributed scheduling with interference-aware power control for an uplink of the UDN operating with time-division duplex (TDD). In the proposed technique, each user adjusts transmit power according to a pre-determined threshold of generating interference to other cell base stations (BSs) and each BS selects the users having the highest effective channel gains adjusted according to the transmit power of users. We assume that each user has a single transmit antenna and each BSs have M receive antennas. It is shown that the proposed technique with a carefully chosen threshold significantly outperforms the existing distributed user scheduling schemes through extensive simulations. In addition, we prove that the optimal multiuser diversity gain, i.e., log log N is achieved by the proposed technique in each cell even in the presence of intercell interference when S = 1, if the number of users in a cell, K-1 N, scales faster than SNR K-1/1-ϵ for a constant ϵ ∈ (0, 1), where S denotes the number of scheduled users.

On the Multi-User Diversity with Fixed Power Transmission in Cognitive Radio Networks

In this letter, we investigate the multi-user diversity (MUD) in an underlay cognitive radio (CR) network where multiple secondary transmitters and primary receivers exist. Many studies on MUD in the underlay CR network have assumed that the secondary transmitters adaptively control their transmit power in order to achieve the {optimal} MUD gain, maintaining the interference at the primary receivers below a pre-determined level. We, however, prove the optimal MUD gain can be also achieved by the fixed power transmission strategy. In contrast to the adaptive power transmission strategy, the fixed power operation in the secondary transmitters relaxes the coordination constraint between the primary and secondary networks, and significantly reduces the signaling and feedback overhead from the secondary transmitters to the secondary receiver.

On the Link Scheduling for Cellular-Aided Device-to-Device Networks

We consider a cellular-aided inband overlay device-to-device (D2D) network, where a base station (BS) and all devices share a frequency band for their communications, but the BS allocates dedicated radio resources to D2D direct communications to avoid the mutual interference between D2D and cellular communications. We first mathematically formulate the optimal sum rate of the D2D network, and provide closed-form approximations of the average sum rate for low and high signal-to-noise ratio (SNR) regimes. Furthermore, we propose two practical D2D link scheduling algorithms: centralized and distributed. The centralized algorithm reduces the computational complexity at the BS, and its performance is shown to be optimal since the SNR of D2D links tends to be either zero or infinity. The distributed algorithm significantly reduces the signaling overhead caused by channel state information feedback from devices to the BS, and the performance loss of the distributed algorithm is marginal compared with that of the centralized algorithm, particularly when the number of D2D pairs is small.

Signal detection with parallel orthogonal matching pursuit in multi-user spatial modulation systems

In this paper, we propose a novel signal detection technique with parallel orthogonal matching pursuit (POMP) for a multi-user spatial modulation (SM) uplink network which consists of a single base station (BS) with Nr antennas and K users with Nt antennas. Each user utilizes the SM, and thus it sends a modulated symbol via a single antenna among Nt antennas. The BS tries to estimate the symbols simultaneously received from K users. In the proposed signal detection technique, the BS modifies the conventional OMP algorithm, known as one of the most promising detection techniques in sparse signal processing field, by selecting multiple candidates M at the first iteration of the OMP algorithm. Simulation results show that the proposed technique significantly outperforms the OMP algorithm in terms of symbol-error rate. It is worth noting that the proposed technique requires M-times more complexity than the OMP-based technique, but it has still much lower complexity than the maximum likelihood detector.

Backhaul traffic reduction using limited feedback in cellular frequency division duplex uplink networks

Abstract In this paper, we propose an enhanced signal-to-generating interference ratio (SGIR)-based resource scheduling scheme to reduce the feedback overhead in backhaul links for frequency division duplex (FDD) uplink networks. In the proposed scheme, each base station (BS) transfers only the information of dominant interference channels greater than a given threshold instead of the whole interference channels. We analyze the performance of the proposed scheme in terms of the amount of feedback reduction in the backhaul links and average uplink sum-rate. In addition, we derive a closed-form solution to determine an adequate threshold level. The numerical results show that the proposed scheme can significantly reduce the amount of feedback traffic in the backhaul links, while yielding almost the same average uplink sum-rate.

Simple and efficient transmission strategies for Device-to-Device caching networks

Abstract For device-to-device (D2D) caching networks, we propose simple transmission strategies in order to minimize the outage probability and maximize the average. We first propose a blanket transmission scheme where multiple caching server devices (CSDs) simultaneously transmit the same content to a RD without any information exchange and signal processing at the CSDs. We also propose an opportunistic transmission scheme where we select a single CSD that has the largest channel gain from a request device (RD), and the selected CSD then transmits the requested content to RD. We derive the outage probabilities and average throughputs and we extend the results to the case of the D2D caching network in the presence of multiple RDs. We also analyze and compare the performances of the proposed transmission strategies according to the threshold rate and transmit signal-to-noise ratio (SNR).

Full-duplex generalized spatial modulation: A compressed sensing-based signal detection (invited paper)

In this paper, we propose a novel low-complexity signal detection technique based on compressed sensing for a full-duplex generalized spatial modulation (FD-GSM) system, where a communication node transmits data symbols via some antennas and receives data symbols via the remaining antennas at the same time. Thus, each antenna operates as either transmitter or receiver in each symbol time, which implies FD-GSM can be implemented with half-duplex antennas. In particular, parallel orthogonal matching pursuit (POMP) algorithm is exploited as a sparse signal recovery algorithm for detecting GSM signals. The self-interference (SI) due to full-duplex operation is assumed to be completely removed by help of the recently proposed SI cancellation techniques. The proposed signal detection technique significantly outperforms the conventional OMP algorithm in terms of symbol error rate (SER). Interestingly, there exists an optimal number of active antennas for maximizing effective throughput.

Simulator Development of Wireless Avionics Intra-Communications

최근 항공기내 전자장비 간의 유선 하네스를 무선 네트워크로 대체하고자 하는 많은 연구가 항공 산업체를 중심으로 진행되고 있다. 본 논문에서는 이러한 항공기내 무선 네트워크의 핵심 기반 기술을 검증하고 각 계층 기술을 효율적으로 통합 할 수 있는 이벤트 기반 시뮬레이터(ES-WAIC; Event-Based Simulator for Wire...

A fully distributed scheduling algorithm for D2D networks

We investigate a cellular-aided overlay device-to-device (D2D) network where a base station (BS) has a perfect control of all D2D operations such as pairing and link scheduling, and there exist no mutual interference between D2D communication and cellular communication because they do not share radio resource. Although optimal sum-rate can be theoretically achieved if the BS has perfect channel state information (CSI), it causes catastrophic signaling overhead and computational complexity. Thus, we propose a fully distributed link scheduling algorithm which requires no signaling and causes no computational complexity. Our simulation results show that the proposed scheme can achieve a near optimal sum-rate.

A New Cell Selection Scheme For Heterogeneous Mobile Communication Networks

Recently, heterogeneous mobile communication network is attracting plenty of interest to serve explosively increasing mobile data traffic. Although the heterogeneous mobile communication network can enhance spatial reuse ratio by using both conventional macro cells and small cells simultaneously, it causes the unbalance in performance of downlink and uplink. In this paper, we propose a new cell selection scheme for heterogeneous mobile communication network. In the proposed cell selection scheme, mobiles select their home cells by considering both uplink and downlink performance, contrary to conventional schemes. We analyze the performance of the proposed scheme in terms of average cell transmission rate through system level simulations and compare it with those of conventional schemes. 키워드 : 이종망, 소형셀, 셀 선택, 홈 셀 Key word : Heterogeneous networks, small cells, cell selection, home cell Journal of the Korea Institute of Information and Communication Engineering 한국정보통신학회논문지(J. Korea Inst. Inf. Commun. Eng.) Vol. 18, No. 10 : 2397~2402 Oct. 2014