Dispersed beamforming approach for secure communication in UDN


Wireless communication systems are prone to many security breaches due to open nature of the medium and exponential a rise in subscribers. Hence, physical layer security (PLS) has emerged as one of the dominant low complexity alternatives to overcome the impact of eavesdropping by managing the physical characteristics of the medium. In this paper, we ensure PLS to moving users which tends to experience rise in handover, as a result of proximity between users and base station. This study is based on ultra-dense network (UDN). To tackle this challenge, novel secure beamforming named as beam broadening and beam merging have been proposed. Besides, we propose a synchronization approach called synchronized mobility clustering for UDN to reduce the overheads generated due to the exchange of information about moving users. More specifically, we derive an analytical expression for secrecy outage probability—an important security metric. The effect of proposed approaches have been validated through numerical results and the results show the effectiveness of the proposed approaches against eavesdropping. Finally, the performance of the proposed scheme is evaluated and compared with the conventional beamforming approach. However, this proposed approach works well for a varied density of users and location to be targeted.

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  1. 1.

    Secrecy rate can be termed as the data rate (in bps/Hz) which can be securely transmitted from one node to another, without being intercepted by the eavesdropper.

  2. 2.

    HPBW: Half Power Beam Width.


  1. 1.

    Paper, W. (2018). Cisco ultra 5G packet core solution.

  2. 2.

    Wang, Y., et al. (2017). A data-driven architecture for personalized QoE management in 5G wireless networks. IEEE Wireless Communications,24(1), 102–110.

    Article  Google Scholar 

  3. 3.

    Zhang, R., Song, L., Han, Z., & Jiao, B. (2012). Physical layer security for two-way untrusted relaying with friendly jammers. IEEE Transactions on Vehicular Technology,61(8), 3693–3704.

    Article  Google Scholar 

  4. 4.

    Su, Z., Hui, Y., & Guo, S. (2016). D2D-based content delivery with parked vehicles in vehicular social networks. IEEE Wireless Communications,23(4), 90–95.

    Article  Google Scholar 

  5. 5.

    Jiang, L., et al. (2016). Social-aware energy harvesting device-to-device communications in 5G networks. IEEE Wireless Communications,23(4), 20–27.

    Article  Google Scholar 

  6. 6.

    Su, Z., Xu, Q., Hui, Y., Wen, M., & Guo, S. (2017). A game theoretic approach to parked vehicle assisted content delivery in vehicular ad hoc networks. IEEE Transactions on Vehicular Technology,66(7), 6461–6474.

    Article  Google Scholar 

  7. 7.

    Osseiran, A., et al. (2014). Scenarios for 5G mobile and wireless communications: The vision of the METIS project. IEEE Communications Magazine,52(5), 26–35.

    Article  Google Scholar 

  8. 8.

    Kamel, M., Hamouda, W., & Youssef, A. (2016). Ultra-dense networks: A survey. IEEE Communications Surveys & Tutorials,18(4), 2522–2545.

    Article  Google Scholar 

  9. 9.

    Duan, X., & Wang, X. (2015). Authentication handover and privacy protection in 5G hetnets using software-defined networking. IEEE Communications Magazine,53(4), 28–35.

    Article  Google Scholar 

  10. 10.

    Shiu, Y. S., Chang, S. Y., Wu, H. C., Huang, S. C. H., & Chen, H. H. (2011). Physical layer security in wireless networks: A tutorial. IEEE Wireless Communications,18(2), 66–74.

    Article  Google Scholar 

  11. 11.

    Chopra, G., Jha, R. K., & Jain, S. (2017). A survey on ultra-dense network and emerging technologies: Security challenges and possible solutions. Journal of Network and Computer Applications,95, 54–78.

    Article  Google Scholar 

  12. 12.

    Chopra, G., Jain, S., & Jha, R. K. (2018). Possible security attack modeling in ultradense networks using high-speed handover management. IEEE Transactions on Vehicular Technology,67(3), 2178–2192.

    Article  Google Scholar 

  13. 13.

    Sivanesan, K., Zou, J., Vasudevan, S., & Palat, S. (2015). Mobility performance optimization for 3GPP LTE HetNets. In Design and deployment of small cell networks (pp. 1–30).

  14. 14.

    Kutty, S., & Sen, D. (2016). Beamforming for millimeter wave communications: An inclusive survey. IEEE Communications Surveys & Tutorials,18(2), 949–973.

    Article  Google Scholar 

  15. 15.

    Sun, L., & Du, Q. (2017). Physical layer security with its applications in 5G networks: A review. China Communications,14(12), 1–14.

    Article  Google Scholar 

  16. 16.

    Lv, T., Gao, H., & Yang, S. (2015). Secrecy transmit beamforming for heterogeneous networks. IEEE Journal on Selected Areas in Communications,33(6), 1154–1170.

    Article  Google Scholar 

  17. 17.

    Zhang, Y., Ko, Y., Woods, R., & Marshall, A. (2017). Defining spatial secrecy outage probability for exposure region-based beamforming. IEEE Transactions on Wireless Communications,16(2), 900–912.

    Article  Google Scholar 

  18. 18.

    Han, B., Li, J., Su, J., Guo, M., & Zhao, B. (2015). Secrecy capacity optimization via cooperative relaying and jamming for WANETs. IEEE Transactions on Parallel and Distributed Systems,26(4), 1117–1128.

    Article  Google Scholar 

  19. 19.

    Costello, D. J. (2009) Fundamentals of wireless communication (Tse, D. and Viswanath, P.) [book review], 55(2).

  20. 20.

    Barros, J., & Rodrigues, M. R. D. (2006). Secrecy capacity of wireless channels. In IEEE international symposium on information theoryProceedings (pp. 356–360).

  21. 21.

    Liang, Y., Poor, H. V., & Shamai, S. (2008). Secure communication over fading channels. IEEE Transactions on Information Theory,54(6), 2470–2492.

    MathSciNet  MATH  Article  Google Scholar 

  22. 22.

    Gopala, P. K., Lai, L., & El Gamal, H. (2008). On the secrecy capacity of fading channels. IEEE Transactions on Information Theory,54(10), 4687–4698.

    MathSciNet  MATH  Article  Google Scholar 

  23. 23.

    Cumanan, K., Ding, Z., Sharif, B., Tian, G. Y., & Leung, K. K. (2014). Secrecy rate optimizations for a MIMO secrecy channel with a multiple-antenna eavesdropper. IEEE Transactions on Vehicular Technology,63(4), 1678–1690.

    Article  Google Scholar 

  24. 24.

    Liu, R., Maric, I., Spasojevic, P., & Yates, R. D. (2008). Discrete memoryless interference and broadcast channels with confidential messages: Secrecy rate regions. IEEE Transactions on Information Theory,54(6), 2493–2507.

    MathSciNet  MATH  Article  Google Scholar 

  25. 25.

    Choi, J. (2016). A robust beamforming approach to guarantee instantaneous secrecy rate. IEEE Transactions on Wireless Communications,15(2), 1076–1085.

    Article  Google Scholar 

  26. 26.

    Xiong, K., Wang, B., Jiang, C., & Liu, K. J. R. (2017). A broad beamforming approach for high-mobility communications. IEEE Transactions on Vehicular Technology,66(11), 10546–10550.

    Article  Google Scholar 

  27. 27.

    Zhu, F., & Yao, M. (2016). Improving physical-layer security for CRNs using SINR-based cooperative beamforming. IEEE Transactions on Vehicular Technology,65(3), 1835–1841.

    Article  Google Scholar 

  28. 28.

    Eltayeb, M. E., Choi, J., Al-Naffouri, T. Y., & Heath, R. W. (2017). Enhancing secrecy with multiantenna transmission in millimeter wave vehicular communication systems. IEEE Transactions on Vehicular Technology,66(9), 8139–8151.

    Article  Google Scholar 

  29. 29.

    Yan, S., & Malaney, R. (2016). Location-based beamforming for enhancing secrecy in rician wiretap channels. IEEE Transactions on Wireless Communications,15(4), 2780–2791.

    Article  Google Scholar 

  30. 30.

    Tsai, J. A., Buehrer, R. M., & Woerner, B. D. (2004). BER performance of a uniform circular array versus a uniform linear array in a mobile radio environment. IEEE Transactions on Wireless Communications,3(3), 695–700.

    Article  Google Scholar 

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Correspondence to Rakesh Kumar Jha.

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Proof of Lemma 1

As defined earlier, it can defined as the probability that the secrecy rate falls below a desired threshold. It is an important physical layer security parameter and used widely to determine the performance of the network for a proposed security algorithm. Rewriting (11) to derive the generalized expression for SOP as

$$S_{r} = \hbox{max} \left[ {C_{i} - C_{e} } \right]^{ + } = \hbox{max} \left[ {log_{2} \left( {1 + \gamma_{i} } \right) - log_{2} \left( {1 + \gamma_{e} } \right)} \right]^{ + } ,$$
$$S_{r} = log_{2} \left( {\frac{{1 + \gamma_{i} }}{{1 + \gamma_{e} }}} \right),$$

We then express the cumulative distribution function (CDF) of \(\gamma_{i}\) as

$$F\left( {\gamma_{i} } \right) = 1 - { \exp }\left( {\frac{{ - \gamma_{i} }}{{\bar{\gamma }_{i} }}} \right),\gamma_{i} > 0$$

As such, the corresponding PDF of \(\gamma_{i}\) can be written as

$$f\left( {\gamma_{i} } \right) = \frac{1}{{\bar{\gamma }_{i} }}\exp \left( {\frac{{ - \gamma_{i} }}{{\bar{\gamma }_{i} }}} \right),$$

where \(\bar{\gamma }_{i}\) is the average SINR of the ith user at a distance of \(d_{i,b}\) meters from bth serving BS. The expected \(\bar{\gamma }_{i}\) can be expressed as

$$\bar{\gamma }_{i} = \frac{{P_{u} E\left\{ {\left\| {\varvec{h}_{i,b} } \right\|} \right\}}}{{\sigma_{i}^{2} }},$$

Similarly, the CDF \(\left( {F\left( {\gamma_{e} } \right)} \right)\) and PDF \(\left( {f\left( {\gamma_{e} } \right)} \right)\) of eve can be written as

$$F\left( {\gamma_{e} } \right) = 1 - { \exp }\left( {\frac{{ - \gamma_{e} }}{{\bar{\gamma }_{e} }}} \right),\gamma_{e} > 0,$$
$$f\left( {\gamma_{i} } \right) = \frac{1}{{\bar{\gamma }_{e} }}\exp \left( {\frac{{ - \gamma_{e} }}{{\bar{\gamma }_{e} }}} \right),$$

The variables \(\gamma_{i}\) and \(\gamma_{e}\) are independent and identically distributed random variable and the joint probability distribution function of \(\gamma_{i}\) and \(\gamma_{e}\) can represented as

$$f\left( {\gamma_{i} ,\gamma_{e} } \right) = f\left( {\gamma_{i} } \right).f\left( {\gamma_{e} } \right) = \frac{1}{{\bar{\gamma }_{i} \bar{\gamma }_{e} }}\exp \left( { - \frac{{\gamma_{e} }}{{\bar{\gamma }_{e} }} - \frac{{\gamma_{i} }}{{\bar{\gamma }_{i} }}} \right),$$

From the basic definition of SOP, we have

$$P_{o} \left( {R_{t} } \right) = Pr\left( {S_{r} < \left. {R_{t} } \right|\gamma_{i} } \right),$$

Putting (27) in above equation, we get

$$= Pr\left( {log_{2} \left( {\frac{{1 + \gamma_{i} }}{{1 + \gamma_{e} }}} \right) < \left. {R_{t} } \right|\gamma_{i} < \gamma_{e} } \right),$$

On rearranging the above equation, we have

$$= Pr(\gamma_{i} < \left. {2^{{R_{t} }} \left( {1 + \gamma_{e} } \right) - 1} \right|\gamma_{i} < \gamma_{e} ),$$
$$P_{o} \left( {R_{t} } \right) = 1 - \mathop {\iint }\limits_{{\gamma_{i} < 2^{{R_{t} }} \left( {1 + \gamma_{e} } \right) - 1}}^{{}} f\left( {\gamma_{i} ,\gamma_{e} } \right) d\gamma_{i } d\gamma_{e} ,$$
$$= \mathop \smallint \limits_{0}^{\infty } \begin{array}{*{20}c} {\frac{1}{{\bar{\gamma }_{i} }}\exp \left( {\frac{{ - \gamma_{i} }}{{\bar{\gamma }_{i} }}} \right)d\gamma_{i} } & {\mathop \smallint \limits_{{\gamma_{i} }}^{{2^{{R_{t} }} \left( {1 + \gamma_{e} } \right) - 1}} \frac{1}{{\bar{\gamma }_{e} }}\exp \left( {\frac{{ - \gamma_{e} }}{{\bar{\gamma }_{e} }}} \right)d\gamma_{e} } \\ \end{array} ,$$
$$= 1 - \frac{{\bar{\gamma }_{i} }}{{\bar{\gamma }_{i} + \bar{\gamma }_{e} 2^{{R_{t} }} }}\exp \left( { - \frac{{2^{{R_{t} }} - 1}}{{\bar{\gamma }_{i} }}} \right),$$

Hence, for a given set of values for \(\bar{\gamma }_{i}\) and \(\bar{\gamma }_{e}\), the resultant expression for secrecy outage is presented as (39).

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Chopra, G., Jha, R.K. & Jain, S. Dispersed beamforming approach for secure communication in UDN. Wireless Netw 26, 3227–3244 (2020). https://doi.org/10.1007/s11276-019-02147-8

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  • Beamforming
  • Security
  • UDN
  • SNR
  • Beam merging
  • Beam broadening
  • Secrecy outage probability