RAKE versus noisy-template based UWB receivers under timing and channel estimation errors

Two popular UWB receivers, the RAKE correlator and noisy-template (NT) auto-correlator, are evaluated and compared under realistic channel and timing estimation errors. A unified performance analysis framework is developed under the notion of receiver operating efficiency (ROE), which measures the effective received energy of a practical receiver against that of an ideal receiver. ROE expressions show that a RAKE receiver is limited by its energy capture capability, which is reflected not only in the number of RAKE fingers employed, but also in the timing offset estimator errors occurring at these fingers. An NT receiver is fairly robust to timing errors but is subject to noise enhancement effects, which can be alleviated by using transmissions with higher duty cycle and more training symbols. Through ROE, these critical system parameters are evaluated in terms of their contributions to overall detection accuracy. Such results are useful in identifying the preferred operating regimes of each receiver. Conversely, given practical operating conditions and system constraints, they help to select the more effective receiver structure and guide the design of key system parameters.