Yuhan Ruan

Performance Analysis of Hybrid Satellite-Terrestrial Cooperative Networks with Distributed Alamouti Code

In this paper, we investigate the performance of a distributed space-time coding based hybrid satellite- terrestrial cooperative network (DSTC-HSTCN), where both the satelliterelay and satellite-destination links undergo the Shadowed-Rician fading, whereas the relay-destination link follows the Rayleigh fading. In particular, we address the problem in a downlink distributed Alamouti coded satellite system with a single fixed terrestrial relay. By assuming that amplify-and-forward (AF) protocol is adopted at the terrestrial relay, we first derive the analytical expressions for the joint probability density function (PDF) and moment generating function (MGF) of the signal to noise ratio (SNR) for the cooperatively encoding phase. Then, based on the Meijer-G functions, we present an approximated yet accurate method to evaluate the outage probability and symbol error rate (SER) of the considered networks. Finally, Simulation results are provided to demonstrate the validity of the theoretical analysis.

Outage Performance of Integrated Satellite-Terrestrial Networks With Hybrid CCI

We investigate the outage performance of an integrated satellite-terrestrial network undergoing hybrid co-channel interference (CCI), which comprises inter-component CCI from the satellite and intra-component CCI from adjacent base stations. Taking the interference power constraints imposed by satellite communications into account, we derive a closed-form expression for the outage probability (OP) of the terrestrial network, where the satellite link and terrestrial links are modeled as shadowed-Rician and Nakagami-m fading, respectively. Finally, simulation results demonstrate the validity of the theoretical analysis and show the effects of various key parameters on the OP performance.

CQI-Based interference management scheme for D2D communication underlaying cellular networks

Device-to-device (D2D) communication has been proposed to be incorporated into future cellular networks for improving capacity, offloading traffic of base station, etc. However, the mutual interference between D2D and cellular users can degrade the performance of networks. To solve this problem, we proposed a channel quality indicator (CQI) based interference management scheme in this paper. Specifically, a resource reuse scheme which enables more D2D pairs to reuse cellular resources and optimises the power efficiency through minimizing power increment is proposed. Simulation results demonstrate the proposed strategy notably improves the access grant probability of D2D users and increases the power efficiency of D2D communication and cellular networks.

Energy Efficient Adaptive Transmissions in Integrated Satellite-Terrestrial Networks With SER Constraints

Allowing frequency reuse between satellite and terrestrial networks, the integrated satellite-terrestrial network can spatially optimize the usage of scarce spectrum resource and is thus becoming one of the most promising infrastructures for future multimedia services. Taking the requirements of both efficiency and reliability in satellite communications into account, we propose an adaptive transmission scheme for the integrated network in this paper, where the satellite can communicate with the destination user either in direct mode or in cooperative mode. Specifically, we first investigate the symbol error rate (SER) performance of two transmission modes with co-channel interference under composite multipath/shadowing fading. Taking the derived SERs as constraints, we formulate the adaptive transmission scheme as an optimization problem with the objective of maximizing energy efficiency (EE) and discuss the trade-off among EE, spectral efficiency (SE), and SER. Furthermore, economic efficiency is also analyzed as a complementary performance measure to SE and EE. Simulation results show that the proposed scheme can increase the attainable EE of satellite communications, which indicates that we should choose the transmission mode adaptively according to different interfering scenarios and shadowing degrees, rather than adopting cooperative transmission aggressively.

Effective capacity analysis for underlay cognitive satellite-terrestrial networks

In this paper, we consider a cognitive satellite-terrestrial network where the satellite communication operates in the microwave frequency bands allocated to terrestrial networks in an underlay mode. Taking the statistical delay quality-of-service (QoS) requirements into account, we investigate the effective capacity of the satellite network while satisfying interference-power limitations imposed by terrestrial networks. Specifically, the primary terrestrial transmitters that would result in aggregate interference at the satellite receiver are modeled as points of a Poisson point process (PPP). By characterizing the aggregate interference as a gamma distribution, we obtain a closed-form expression for the effective capacity of the secondary satellite network. Finally, simulation results are provided to not only demonstrate the validity of the theoretical results, but also show the effects of system parameters such as delay exponent of satellite communications, interference-power limitations of terrestrial networks, and intensity of terrestrial transmitters on the performance of the satellite network.

Symbol Error Analysis of Distributed Space-Time Coded Hybrid Satellite-Terrestrial Cooperative Networks

In this paper, the performance of a distributed Space-Time coded hybrid satellite-terrestrial cooperative network (DSTC-HSTCN) is investigated. In particular, we address the problem in a downlink distributed Alamouti coded satellite system with a single fixed terrestrial relay adopting amplify-and- forward protocol. By modeling the satellite- relay/destination and relay-destination links as Shadowed-Rician and Rayleigh distributions, respectively, we derive a closed-form expression for average symbol error rate (SER) with quadrature phase shift keying modulation. Simulation results verify the validity of the theoretical analysis and show the performance improvement of the hybrid satellite- terrestrial cooperative network (HSTCN).

Performance evaluation for underlay cognitive satellite-terrestrial cooperative networks

With the continuously increasing demand for broadband applications and services, underlay cognitive satellite-terrestrial networks, enabling to accommodate better wireless services within the scarce spectrum, have attracted tremendous attentions recently. In this network, satellite communications are allowed to operate in the frequency bands allocated to terrestrial networks under the interference constraints imposed by terrestrial network, which may lead to a performance degradation of the satellite network. To guarantee the performance of the primary terrestrial network as well as the secondary satellite network, we introduce the cooperation into cognitive satellite-terrestrial networks and investigate the performance of the new framework, i.e., cognitive satellite-terrestrial cooperative network (CSTCN). Specifically, by restricting the transmit power of satellite communications with interference power constraints imposed by terrestrial communications, we firstly obtain the received signal-to-interference-plus-noise ratio (SINR) of the considered network. Moreover, by employing the moment generating function (MGF) approach, closed-form expressions for symbol error rate (SER) and outage probability (OP) of the considered cognitive network are derived. The analytical results obtained in this paper can provide theoretical support for optimizing the performance of satellite-terrestrial networks.

Energy efficient power allocation for underlaying mobile D2D communications with peak/average interference constraints

We evaluate the schemes described in previous section through Monte Carlo simulations. In the simulations, the pathloss model between BS and users is PL=128.1+37.6log10(d [in Km]) and the pathloss model between users is PL=148.1+ 40log10(d [in Km]). We set N0 = −174 dBm/Hz and W =1 MHz. We denote dsd, dsc, and dbd as the distances of SU→DU, SU→CU, and BS→DU links, respectively. Unless specifically stated, we set dsd = 300 m, dcd = 400 m, and dsb = 400 m. For simplicity, we assume that the SU and the DU move toward each other and in the same speed ν = 5 m/s. The velocity of the CU is set to zero. Specific values of channel parameters of the 3D V2V channel model are consistent with [1]. We firstly conduct simulations to demonstrate the impact of P0 on the energy efficiency of underlaying mobile D2D communications in both low VTD and high VTD scenarios, as shown in Fig. A1. As expected, the energy efficiency increases in the beginning and deteriorates afterwards for each P0. The larger the P0 is, the smaller the EE becomes. Nevertheless, the optimal point of SE that maximizes EE moves right as the circuit power consumption increases, which implies that when P0 increases, we need to increase transmit power rather than decreasing it to achieve higher EE, although the total power consumption will increase. Moreover, the EE in low VTD outperforms that in high VTD, where the signals suffer from poor propagation environment. Next, we take the high VTD scenario as an example to illustrate the impact of EE threshold on the transmission power and average achievable EE of mobile D2D communications, where the peak interference constraint is adopted. As shown in Fig. A2, as Ith increases, i.e., larger interference power is acceptable for cellular communications, Ps increases. Due to the transmit power constraint, Ps with different EE thresholds remain unchanged eventually. As expected, the larger ΓEE is, the smaller Ps is. This is because that tight EE constraint restricts the maximum feasible transmission power. Besides, similar to the observation in Fig. A1, EE increases at first and then decreases. Eventually, due to the EE constraint, EE remains constant. Moreover, the higher the EE requirement is, i.e., ΓEE gets larger, the lower the achievable EE is. This is because that ΨEE is the mean value of EE on multiple simulation times. For a given Ith, as ΓSE increases, the probability that ΨEE > ΓEE decreases. When the EE constraint is destroyed, the mobile D2D communication will be terminated and ΨEE is zero. Therefore, from the perspective of statistics, achievable average EE decreases with the EE requirement increases. To illustrate the different impacts of peak and average interference constraints on SE performance of mobile D2D communications, Fig. A3 and Fig. A4 perform the spectral efficiency versus interference threshold for different dsd and ΓEE, respectively. As observed in both figures, the SE with average interference constraint outperforms that with peak interference constraint, since that the peak interference constraint is stricter by restricting resultant interference power at each fading state to be below a predefined value. Meanwhile, the performance gap in high VTD scenario is larger than that in low VTD scenario, which implies it makes much more sense to adapt the transmit power of D2D users according to different QoS requirements of cellular users in high VTD scenario. Moreover, due to the transmit power constraint, the SE with different interference constraints reach the same level eventually in Fig. A3. For Fig. A4, it is interesting to note that a few points are unavailable at the beginning of the SE curves with average interference constraint, which is due to that when the interference constraint is strict, i.e., Ith is small, the permitted transmit power is too small that the EE requirement cannot be satisfied. Moreover, since higher ΓEE requires more transmit power,