Detection of TR UWB signal in the presence of Narrowband Interference Yohannes Alemseged and Klaus Witrisal yohannes@sbox.tugraz.at . Signal Processing and Speech Communication Laboratory spsc.inw.tugraz.at Graz University of Technology, Austria UWB4SN workshop Nov. 4, 2005, Lausanne, Switzerland Detection of TR UWB signal in the presence of Narrowband Interference – p.1/23
� � � � � � Outline Introduction System Model: UWB signal, NBI signal, AcR front end Data model Detection Schemes Simulation Results Conclusion and further outlook Detection of TR UWB signal in the presence of Narrowband Interference – p.2/23
� � � � � � Introduction Tx System: Transmitted Refference(TR) Differential UWB Receiver: TR AutoCorrelation Receiver (AcR) Interferor: IEEE 802.11a WLAN Service Detection of TR UWB signal in the presence of Narrowband Interference – p.3/23
� � � � � � � � � Introduction Why Interference could be adversary for UWB? unregulated spectrum should operate under -41.3dBm/MHz Why AcR is a choosen as a victim receiver? Transmitted Refference Analog front end / Nonlinearity Why IEEE 802.11a WLAN is choosen as interferor? Common spectrum Deployment scenario Detection of TR UWB signal in the presence of Narrowband Interference – p.4/23
System Model Figure 1: System Model D j T s x Integrate & W 1 damp T s Z D j x W 2 T s s ( t ) x W N cr β ( t ) r ( t ) ˆ Detection of TR UWB signal in the presence of Narrowband Interference – p.5/23 a
✬ � ✂ ✦ ✝ ✆ ✄ ✂ ✦ ✫ ✆ ★ ✆ ✵ ✄ ✂ ✁ ✝ ✆ ✬ ✦ ✰ � ✄ ✬ ✤ ✰ ✵ ✶ ✧ ✆ ✄ ✂ ★ ✭ ✱ ✁ ✝ ✭ ✆ ✲✴ ✦ ✫ ✆ ✄ ✂ ✂ ✆ ✄ ✥ ✖ ✰ ✎ ✄ ✂ ✄ ✏ ✟ ✒ ✑ ☛ ✠ ✏ ☛ ✄ ✆ ✞ ☛ ✵ ✞ ✝ ✆ ✷ ✁ ✤ ✖ ✟ ✛ ✎ ✤ ✣ ✢ ✚ ✶ ✮ ✟ ✚ ✏ ✙ ☛ ✏ ✏ ✱ ✒ ✝ ✏ ✲✴ ✒ ✂ � ✆ Detection of TR UWB signal in the presence of Narrowband Interference – p.6/23 System Model: UWB signal ✆✕✧ ✂☎✄ ✙✜✛ ✬✯✮ , ✂☎✄ ) ✓✕✔ ✟✘✗ is AcR front end filtering effect ( ✆✕✧ ✂☎✄ ☞✍✌ ✟✘✗ For differential TR scheme, ✱✳✲✴ ✟✡✠ ✆✪✩ ✂☎✄ ✂☎✄ Received Signal: ✆✕✧ ✆✕✧ ✂☎✄ UWB signal ✂☎✄ ✂☎✄ ✱✳✲✴
✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ � ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✍ ☎ ✆ ✭ ✴ ✢ ✜ ✢ ✜ ✧ ★ ✒ ✩ ✂ ✤ ✥ ✩ ✤ ✥ ✪ ★ ✒ ✍ ✫ ✆ ✬ ✤ ☎ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✂ ✛ ✛ ✛ ✛ ✛ ✛ ✛ ✼ ✻ ✭ ✵✶ ✴ ✛ ✛ ☎ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✞ ✘ ✁ ✂ ✄ ☎ ✆ ☎ ✤ ✂ ✄ ☎ ☞ ✚ ✌ ✂ ✠ ✔ ✕ ✖ ✽ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✛ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✛ ✛ ✛ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✚ ✢ Detection of TR UWB signal in the presence of Narrowband Interference – p.7/23 System Model: NBI Model Figure 2: Model of the narrowband interference ✜✣✢ ✗✙✘ f c + W β ☎✮✺ 2 ✑✓✒ NBI, IEEE802.11a OFDM passband signal ✍✏✎ ✤✹✥ otherwise ✷✙✸ P β ✠☛✡ ✝✟✞ ✯✣✢ ✤✦✥ f c − W β 2 ✲✙✳ ✂✱✰ 8 < : ✯✣✢ ✜✣✢ ✂✮✭
✲ ✟ ☞ ☎ ✟ ✆ ✠ ✝ ✔ ✝ ✕ ✒ ✔ ✔ ✝ ✟ ✲ ☞ ✌ ✍ ✟ ✌ ☞ � ✔ ✝ ✟ ✕ ✒ ✔ ✝ ✟ ☞ ✑ ✌ ✍ ✎ ☞ ✏ ✲ ☞ ✌ ✏ ✎ ✏ ✠ ✌ ☞ ✌ ✍ ✎ ☞ ✏ ✲ ☞ ✏ ✟ ✑ ✌ ✝ ✕ ☞ ☎ ✟ ✆ ✒ ✝ ✒ ☞ ☞ ✌ ✏ ✑ ✌ ✒ ✍ ✕ ☎ ✔ ✟ ✆ ✠ ✕ ✔ ✝ ✟ ✕ ✟ ☞ ✆ ✔ ☎ ✌ ✏ ✑ ✌ � ✏ ☞ ☞ ✟ ✲ ✆ ✠ ✎ ✔ ✝ ✟ ✕ ✍ ☞ ✁ ✝ ✌ ✌ ✑ ☞ ☎ ✟ ✆ ✠ ✏ ✕ ✏ ☞ ✒ ✁ ✲ ☞ ✌ ✍ ✎ ☞ ✔ ✟ ✟ ✌ ☞ ✲ ☞ ✌ ✏ ✍ ✒ ☞ ✏ ✏ ✍ ✓ ☞ ✌ ✏ ✏ ✂ ☞ ☎ ✏ ☞ ☞ ✒ ✲ ☞ ✌ ✍ ✎ ☞ ✏ ✍ ☞ ✎ ✌ ✍ ✎ ☞ ✏ ✌ ☞ ✌ ✍ ✠ Detection of TR UWB signal in the presence of Narrowband Interference – p.8/23 System Model: Received Signal Expanding further the correlator output equations; ✍✔✓ ✠☛✡ ✔ ✞✝✟ ✔ ✞✝✟ Z ✁✄✂ ✠☛✡ ✠☛✡ ✠☛✡ ✠☛✡ ✠☛✡ Correlator Output Z Z Z Z Z ✁✄✂ ✽ ✖✕ ✒✘✗
✬ ✠ ✠ ✁ ✒ ✑ ✠ ✤ ✬ ✄ ✚ ✵ ✔ ✬ ✱ ✆ ✏ ✞ � ✄ ✠ ✂ ✒ ✱ ✓ ✠ ✰ ✓ ✒ ✑✒ ✄ ✚ ✥ ✆ ✄ ✂ ✖ ✌ ✆ ✏ ✞ ✬ ✂ ✞ ✌ ✣ ✚ ☞ ✄ ✌ ✚ ✍ ☞ ✄ ✌ ✏ ✁ ✎ � ✌ ✗ ✭ ✆ ✏ ✞ ✬ ✄ ✂ ✭ ☞ ✄ ✘ ✚ ✍ ☞ ✄ ✌ ✝ ✵ ✂ ✰ ✏ ✗ ✠ ✁ ✆ ✄ ✆ ✌ ✛ ✌ ✆ ✏ ✞ ✬ ✜ ✢ � ☞ ✄ ✱ ✒ ✍ ☞ ✄ ✌ ✠ ✤ ✝ ✵ ✂ ✰ ✏ ✗ ✄ System Model: Correlators Output NBI by NBI product term in the data sample ☎✝✆ ✂☎✄ ✭ ✁� ☎✝✆ ✣ ✍✌ ✂☎✄ ✂☎✄ ✥ ✏✎ ✭ ✟� ✡☞☛ ☎✕✆ ✡☞☛ First term can be neglected for ✗✙✘ is in GHz range and is about for indoor ✢✤✣ propagation Detection of TR UWB signal in the presence of Narrowband Interference – p.9/23
� ✘ � ✆ ✢ ✂ ✎ ✁ ✁ ✗ ✎ ✁ � ✩ ✄ ✚ ✥ ✆ ✑✒ ✂ ✂ ✝ � ✝ ✂ � ✁ ✵ ✠ ✘ ✢ ✗ ✩ ✁ ✣ ✆ ✎ ✄☎ ✝ ✄ ✖ ✰ ✞ � ✆ ✒ ✌ ✞ ✏ ✏ ✒ ✏ ✱ ✓ ✠ ✁ ✑✒ ✛ ✎ ✆ ✴ ✰ ✌ ☞ ✆ ✏ ✞ ✬ ✂ ✠ ✓ ✄ ✂ ✌ ✱ ✍ ☞ ✄ ✌ ✝ ✵ ✴ Data Model Fixed phase sinusoid modulated by a Short time autocorrelation function of the baseband NBI signal ✂☎✄ ☎✕✆ ✣ ✍✌ ✂☎✄ ✡☞☛ Samples will be well correlated if For IEEE 802.11a WLAN , ✢✤✣ NBI term can thus be written as; c is a sampled vector of Detection of TR UWB signal in the presence of Narrowband Interference – p.10/23
✝ ✏ ✰ ✂ ✵ � ☞ ✌ ☛ ✎ ✏ ✠ ✑ ✙ ✂ ✂ � ✏ ✰ ✂ ✵ ✖ ✂ ✂ ✫ ✚ ✰ ✂ ✵ ✝ ✣ ✫ ✁ ✬ ✆ ✵ � ✰ ✂ ✵ ✝ ✁ ✚ ✟ ✬ ✂ ✝ � � ✴ ✰ ✂ ✵ ✬ ✄ � ✁ ✂ ✂ ✰ ☎ ✝ Data Model Where ISI is avoided (burst /LDC), a data model can be written as; is due to the "data by data" term, and is a bias term due to interference among pulses In the absence of NBI and noise, detection could be accomplished by; ✆✪✩ ✫ ✆☎ Detection of TR UWB signal in the presence of Narrowband Interference – p.11/23
✣ ✙ � ✘ ✙ ✚ ✂ ✆ ✑ ✙ ✛ ✛ ✜ ✚ ✣ ✝ ✚ ✑ ✂ ✆ ✑ ✎ ✓ ✑ ✝ ✢ ✢ ✆ ✎ ✆ ✆ ★ ✔ ✓ ✎ ✍ ☎ ✟ ☛ ☞ ✠ ✟ ☎ ☞ ✠ ✟ ✌ ✍ ☞ ✍ ☞ � ✠ ✏ ✎ ✝ ☞ ☎ ✟ NBI Mitigation: Least Square Solution Sampled output for ymbols ✁✄✂ ✟✡✠ ✆✞✝ ✁✄✂ ✆✒✑ Find an estimate of that minimizes the following norm ✕✗✖ Setting the derivative of the cost function to zero ✢✡✑ ✙✥✤ ✣✧✦ Implementation requires pilot symbols Detection of TR UWB signal in the presence of Narrowband Interference – p.12/23
✞ ✁ ✝ ☎ ✟ ✝ ✆ ✝ ✁ ✄ � ✆ ✕ ☛ ✎ ✔ ✌ ✛ ✎✑ ✑ ☞ ✆ ✎ ☎ � ✗ � ☎ ✁ ✂ ✄ ☎ ✖ ✆ � ☎ � ✆ ✔ ✝ ✝ ✂ ✎ ✑ NBI Mitigation: Detection based on SVD can be factored as; Where is x data matrix is x unitary matrix and is x unitary matrix ☞✍✌ where ✟✡✠ ✌✓✒ ✎ ✏✎ Correlation of the code vector and the column containing the data from unitary matrix is used for separation Detection of TR UWB signal in the presence of Narrowband Interference – p.13/23
� ✁ ✁ ✔ ✛ � ✁ ☛ ☞ ✝ ✌ ☎ ☛ ✛ ☞ ✝ ✆ ✂ ✌ ☎ ✆ ✍ ☞ ✆ ✎ ✆ ✟ ✟ ☎ � � ✁ ✁ ✂ ✄ ✌ ✝ ✞ ✟ ☞ ✔ ✂ ✎ ✂ ✄ ☎ ✞ ✟ ✁ ☞ ✠ ✎ ✛ NBI Mitigation: Adaptive Constant Modulus Algorithm Constant amplitude of binary antipodal symbols �✝✆ are transmitted ☞ ✡✠ ✟✡✠ The adaptation equation can be written as; ☞ ✡✠ ✟✡✠ Detection of TR UWB signal in the presence of Narrowband Interference – p.14/23
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