High Speed Railway Communication Using Moving Relays
The high-speed railway (HSR) provides more convenience to people, so the main attention is given to provide the reliable communication inside the train. It is the challenging task due to the high mobility of train and frequent need of handoff to each communicating users. In this paper, the individual handoff problem is solved by group handoff by using moving relays (MR) through cooperative communication. The system model for non-cooperative and cooperative communication in multi-tier heterogeneous network is proposed. Two different scenarios for HSR communication i.e. without MR or direct communication and with MR, are discussed. Moreover, effect of interference, noise signal and power control factor are also considered in this paper. The performance of system model is analyzed by handoff probability, outage probability, coverage probability and transmission capacity. The results show that the outage probability and handoff probability decrease and coverage probability and transmission capacity increases as the number of MR increases due to cooperative communication. The analytical results are also veri?ed by the Monte-Carlo simulation.
Due to growing technology, the passengers inside the train demand for the high-speed internet access and best voice quality. In the recent years, several types of research are going on the railway communication. Conventional Global System for Mobile Communications (GSM) is adapted for the railway-speci?c application which is termed as the GSM-R. But it is successful only for voice communication in the high-speed railway (HSR) not for data service. It doesn?t support data rate services for high mobility of trains. To compensate the drawbacks of GSMR, another technology i.e. Long-Term Evolution (LTE) is developed. LTE offers signi?cant improvement such as best network availability and reduced handoff rate. But as
the traf?c increases, the LTE network cannot provide the suf?cient data rate for high mobility vehicles. So, there is the need of next-generation wireless network which provides the suf?cient data rate for high mobility vehicles also. Therefore, cooperative communication gives a standout amongst the most unique ways to deal the restrictions of existing wireless network and is relied upon to give a signi?cant part in the plan of next generations of wireless networks.
- Heterogeneous cloud small cell network (HCSNet). here, The UE has a set of combining vectors that also cover the whole angular space.
- Coordinated multi-point (CoMP) communication
- Conventional Global System for Mobile Communications (GSM) is adapted for the railway-speci?c application which is termed as the GSM-R. But it is successful only for voice communication in the high-speed railway (HSR) not for data service. It doesn?t support data rate services for high mobility of trains.
- LTE offers signi?cant improvement such as best network availability and reduced handoff rate. But as the traf?c increases, the LTE network cannot provide the suf?cient data rate for high mobility vehicles.
- Cooperative communication: In the next generation wireless network, the cooperative communication is the promising key to increase the coverage area, reliability, power and spectral ef?ciency. It involves the third party i.e. relay nodes or MR as a cooperative agent to communicate with their related BS. In this paper, two scenarios are considered under cooperative communication:
- Cooperative communication using one MR
- Cooperative communication using two MR
The main issue in the HSR communication is doppler shift, frequent handoff and vehicle penetration loss (VPL). The problem of Doppler shift occur due to the relative motion of the train versus their serving base station (BS) and can be resolved by using the guard band. The second problem encountered with the HSR is the frequent handoff. The process of handoff from one network to another network happens when the selected BS does not provide the required QoS for the speci?c application.
The millimeter-wave supports wide bandwidth, and the short wavelength of it enables the miniaturization of antennas. Therefore, millimeter-wave-based mobile communication systems can be equipped with more antennas in the same space as long-term evolution (LTE) base stations. However, short wavelengths can cause high path loss and low signal to noise ratio (SNR)
BLOCK DIAGRAM EXPLANATION
A multi-tier heterogeneous network is considered where each tier of heterogeneous network consists of three different class of BS such as one macro cell, many pico-cells and many femto-cells. These BS across different tier may contrast regarding the transmit power, coverage area and their spatial density. Two different type of communications are considered: Non-cooperative and cooperative communication. Here, the non-cooperative communication refers to the direct communication of train user to BS while cooperative communication refers to the involvement of MR for communication to BS. In cooperative communication, two types of scenarios are considered: with one MR and with two MR.
MR is used for either cellular network or two-tier heterogeneous network. Using only one MR for amplifying and forwarding the user signal. In this paper, two antennas i.e. two MR are used which has the advantage of increased performance in terms of different parameters. For two MRs in HSR communication, equal ratio combining (ERC) technique is used with antenna diversity to add the signal from the head and back antenna. The performance of system is analyzed in terms of handoff probability, outage probability, coverage probability and transmission capacity.
MATLAB 2018 and above
In this paper, the effect of cooperative and non-cooperative communication for multi-tier heterogeneous network is investigated. The cooperative communication is possible with the help of MR by using the concept of group mobility. In the multi-tier heterogeneous environment of the macrocell, picocell, and femtocell, the effect of one MR, two MR and without MR is tested. The performance is evaluated in terms of outage probability, coverage probability, handoff probability and transmission capacity. The cooperative communication with two MR reduces outage probability, handoff probability and enhances transmission capacity compared to one MR. The cooperative communication by using two MR proves best in terms of all parameters.
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