Further improvements could include the customization of channel parameters, like the addition of antenna gains, frequency dependence of path gains, shadowing or large-scale fading and distance dependence of the pathloss. This will allow to simulate the expected BEP over distance for each environment and build specific receiver according to the environment needs. More information regarding the way of application can be found in [2].
Another idea is combining the MRC diversity gains with the MLSE & RAKE ability to mitigate interference in high ISI environments. The MRC receiver has proven to perform well in cases that the capture energy by the RAKE fingers is significant to the total received energy. In the case of a high delay profile environment like outdoor were the RAKE captured energy is low and ISI is high, a possible combination of the two receivers would provide an optimal implementation however with increased complexity.
Finally it would be interesting the application of block Decision Feedback Equalization (DFE) [22]. Many papers can be found in literature regarding DFE but specifically in [23] we can see a generalized MLSE arbitration for High Speed Packet Access (HSPA) Wideband Coded Division Multiple Access (WCDMA). Original block equalization involves joint detection of symbols from an overall symbol period and the use of a feedback filter in order to remove the interference from that past symbol period. They extend the idea to parallel symbol streams, add feedforward filtering and introduce a notion of block linear equalization. Been able to work in a codeword level to remove the ISI will provide more effective power to the MRC receiver, which will perform better with the maximum diversity.
References
[1] IEEE 802.15.4-2011, “IEEE Standard for Local and Metropolitan Area Networks–Part 15.4: Low-Rate Wireless Personal Area Networks (LR- WPANs),” New York, NY, USA, IEEE, Sep. 2011.
[2] A. Molisch et al., “A comprehensive standardized model for ultrawideband propagation channels,” IEEE Trans. Antennas and Propag., vol. 54, no. 11, pp. 3151–3166, Nov. 2006.
[3] Z. Ahmadian and L. Lampe, “Performance analysis of the IEEE 802.15.4a UWB system,” IEEE Trans. Commun., vol. 57, no. 5, pp. 1474–1485, May 2009.
[4] S. Kim, Y. Kim, X. Li, and J. Kang, “Orthogonal pulse design in consideration of FCC and IEEE 802.15.4a constraints.” IEEE Commun. Letters, vol. 17, no. 5, pp. 896–899, May 2013.
[5] I. Dotlic and R. Kohno, “Low complexity chirp pulsed ultra-wideband system with near-optimum multipath performance,” pp. 208–218, Jan. 2011. [6] S. Ji, S. Lee, and J. Kim, “Efficient hybrid modulation with phase-directed
pulse position estimation for UWB-IR systems.” IEEE Trans. Commun., vol. 61, no. 3, pp. 1171–1177, Mar. 2013.
[7] I. Dotlic and R. Miura, “Novel trellis coded modulation for coherent IEEE 802.15.4a impulse-radio ultra-wideband communications,” in Proc. IEEE In- ternational Conference on Intelligent Sensors, Sensors Networks and Informa- tion Processing (ISSNIP’14), Singapore, Apr. 2014, pp. 1–6.
[8] L. Reggiani and G. Maggio, “Orthogonal convolutional modulation for uwb- impulse radio systems: performance analysis and adaptive schemes,” Wire- less Communications, IEEE Transactions on, vol. 8, no. 9, pp. 4550–4560, September 2009.
[9] D. Cassioli, M. Win, F. Vatalaro, and A. Molisch, “Low complexity rake re- ceivers in ultra-wideband channels,” Wireless Communications, IEEE Trans- actions on, vol. 6, no. 4, pp. 1265–1275, April 2007.
REFERENCES 33
[10] S. Wang, Y. Chen, M. Leeson, and N. Beaulieu, “New receivers for generalized uwb transmitted reference systems with improved performances,” Wireless Communications, IEEE Transactions on, vol. 9, no. 6, pp. 1837–1842, June 2010.
[11] H. Shao and N. Beaulieu, “An analytical method for calculating the bit er- ror rate performance of rake reception in uwb multipath fading channels,” Communications, IEEE Transactions on, vol. 58, no. 4, pp. 1112–1120, April 2010.
[12] P. Kaligineedi and V. K. Bhargava, “A chip-rate MLSE equalizer for DS-UWB systems,” in Proc. National Conference on Communications (NCC’06), New Delhi, India, Jan. 2006, pp. 78–82.
[13] X. N. S. Yang, Q. Yin and Z. Li, “A DS-UWB interpath interference suppres- sion scheme based on MLSE algorithm,” in Proc. International Conference on Signal Processing (ICSP) 2006), Beijing, China, Nov. 2006, pp. 1–3.
[14] M. Eslami and X. Dong, “Rake-MMSE-equalizer performance for UWB,” IEEE Commun. Letters, vol. 9, no. 6, pp. 502–504, June 2005.
[15] N. Boubaker and K. B. Letaief, “Mmse multipath diversity combining for multi-access th-uwb in the presence of nbi.” IEEE Transactions on Wireless Communications, vol. 5, no. 4, pp. 712–719, 2006.
[16] F. Troesch and A. Wittneben, “Low power UWB transceivers for isi limited environments: Design and performance verification,” in Proc. IEEE Interna- tional Conference on Ultra-Wideband (ICUWB) 2009, Vancouver, Canada, Sep. 2009, pp. 269–273.
[17] S. Jamali, N. Le, and T. Le-Ngoc, Coded-Modulation Techniques for Fad- ing Channels, ser. Kluwer international series in engineering and computer science: Communications and information theory. Springer US, 1994. [18] S.-W. Lee and B. V. K. V. Kumar, “Soft-decision decoding of Reed-Solomon
codes using successive error-and-erasure decoding,” in Proc. IEEE Global Telecommunications Conference (GLOBECOM) 2008, New Orleans, LO, USA, Dec. 2008, pp. 1–5.
[19] M. Di Benedetto, UWB Communication Systems: A Comprehensive Overview. Hindawi Publishing Corporation, 2006.
[20] S. Kim, Y. Kim, X. Li, and J. Kang, “Orthogonal pulse design in consideration of fcc and ieee 802.15.4a constraints,” Communications Letters, IEEE, vol. 17, no. 5, pp. 896–899, may 2013.
[21] J. Proakis and M. Salehi, Digital Communications, ser. McGraw-Hill higher education. McGraw-Hill Education, 2007.
REFERENCES 34
[22] D. Williamson, R. Kennedy, and G. Pulford, “Block decision feedback equal- ization,” Communications, IEEE Transactions on, vol. 40, no. 2, pp. 255–264, Feb 1992.
[23] G. Bottomley, “Block equalization and generalized mlse arbitration for the hspa wcdma uplink,” in Vehicular Technology Conference, 2008. VTC 2008- Fall. IEEE 68th, Sept 2008, pp. 1–5.
Pe rf o rm an ce E va lu at io n o f 8 02 .1 5. 4 U W B P H Y f o r H ig h S p ee d D at a R at e u n d er I EE E C h an n el Mo de l
Department of Electrical and Information Technology, Faculty of Engineering, LTH, Lund University, June 2015.
Performance Evaluation
of 802.15.4 UWB PHYfor High
Speed Data Rate under IEEE
Channel Model
Athanasios Vasileiadis
A th an a si o s V a si lei a d isMaster’s Thesis
Series of Master’s theses
Department of Electrical and Information Technology LU/LTH-EIT 2015-452