# Derivation and Analysis of the BER Closed Form in the OFDM Communication System with IQ Imbalance

• Hieu Nguyen Thanh (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University) ;
• Kang Byung-Su (RF Technology Team, Mobile Telecommunication Research Division, ETRI) ;
• Lee Kwang-Chun (RF Technology Team, Mobile Telecommunication Research Division, ETRI) ;
• Ryu Heung-Gyoon (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University)
• Published : 2006.09.01
• 77 6

#### Abstract

Orthogonal frequency division multiplexing(OFDM) is very useful for the wireless communication system. However, OFDM is very sensitive to the radio frequency impairments. One of the most important major impairments is the IQ imbalance between in-phase(l) and quadrature(Q) branches in the up and down-conversion. IQ imbalance can be divided into phase and amplitude imbalances. These imbalances make constellation of signal to expand and rotate. The performance of system is severely degraded. In this paper, a closed-form for the bit error probability of the OFDM signal in IQ imbalance environment is derived in terms of the function of phase and amplitude imbalance parameters. So, it will be convenient and useful to evaluate the performance of OFDM communication system with IQ imbalance. It is confirmed that computer simulation results closely match with the results of the analytical derivation. When phase imbalance $\varphi=20^{\circ}$, amplitude imbalance $\varepsilon=0.1$; 0.3; 0.4; 0.5, BER at $10^{-5}$ is severely degraded by 1.8 dB, 3.12 dB, 4.72, and 8.44 dB, respectively.

#### Keywords

BER;OFDM;IQ Imbalance;QAM

#### References

1. B. Razavi, RF Microelectronics, Prentice Hall, Upper Saddle River, NJ, 1998
2. A. Tarighat, A. H. Sayed, 'MIMO OFDM receivers for systems with IQ imbalances', IEEE Transactions on Signal Processing, vol. 53, Issue 9, pp. 3583-3596, Sep. 2005 https://doi.org/10.1109/TSP.2005.853148
3. J. Tubbax et al., 'Joint compensation of IQ imbalance and frequency offset in OFDM systems', IEEE Global Telecommunications Conference GLOBECOM '03, vol. 4, pp. 2365-2369, Dec. 2003
4. J. Tubbax et al., 'Compensation of IQ imbalance and phase noise in OFDM systems', IEEE Transactions on Wireless Communications, vol. 4, Issue 3, pp. 872-877, May 2005 https://doi.org/10.1109/TWC.2004.843057
5. B. Razavi, 'Design considerations for direct-conversion receivers', IEEE Transactions on Circuits and Systems II, vol. 44, Issue 6, pp. 428-435, Jun. 1997 https://doi.org/10.1109/82.592569
6. U. Reimers, 'Digital video broadcasting', IEEE Commun. Mag., vol. 36, Issue 6, pp. 104-110, Jun. 1998
7. A. A. Abidi, 'Direct-conversion radio transceivers for digital communications', IEEE Journal of Solid-State Circuits, vol. 30, Issue 12, pp. 1399- 1410, Dec. 1995 https://doi.org/10.1109/4.482187
8. M. Buchholz, A. Schuchert, and R. Hasholzner, 'Effects of tuner IQ imbalance on multicarriermodulation systems', Proc. IEEE International Caracas Conference on Devices, Circuits and Systems, pp. T65/1-T65/6, Mar. 2000
9. C. L. Liu, 'Impacts of I/Q imbalance on QPSKOFDM-QAM detection', IEEE Transactions on Consumer Electronics, vol. 44, Issue 3, pp. 984-989, Aug. 1998 https://doi.org/10.1109/30.713223
10. P. Baudin, F. Belveze, 'Impact of RF impairments on a DS-CDMA receiver', IEEE Transactions on Communications, vol. 52, Issue 1, pp. 31-36, Jan. 2004 https://doi.org/10.1109/TCOMM.2003.822159
11. H. Shafiee, S. Fouladifard, 'Calibration of IQ imbalance in OFDM transceivers', IEEE International Conference on Communications ICC '03, vol. 3, pp. 2081-2085, May 2003
12. Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer(PHY) Specifications: High-Speed Physical Layer in the 5 GHz Band, IEEE Standard 802.11a-1999
13. M. Valkama, M. Renfors, and V. Koivunen, 'Advanced methods for I/Q imbalance compensation in communication receivers', IEEE Transactions on Signal Processing, vol. 49, Issue 10, pp. 2335-2344, Oct. 2001 https://doi.org/10.1109/78.950789
14. A. Schuchert, R. Hasholzner, and P. Antoine, 'A novel IQ imbalance compensation scheme for the reception of OFDM signals', IEEE Transactions on Consumer Electronics, vol. 47, Issue 3, pp. 313-318, Aug. 2001 https://doi.org/10.1109/30.964115
15. P. Rykaczewski, M. Valkama, M. Renfors, 'Analytical approach to I/Q imbalance in OFDM, CDMA and MC-CDMA based systems', IEEE Radio and Wireless Symposium, pp. 555-558, 2006
16. Local and Metropolitan Area Networks-Part 16, Air Interface for Fixed Broadband Wireless Access System, IEEE Standard 802.16a