Cognitive OFDM system detection using pilot tones second and third-order cyclostationarity

GLR test for OFDM system identification using pilot tones pattern

“…In this case, the overall complexity of their algorithm is approximately 5.4 × 10 5 MAC where each MAC consists of one complex multiplication and one addition. For this case, the complexity of our proposed algorithm is 6.45 × 10 5 operations which is slightly more expensive (less than 19 %) than the one proposed in [24]. Since the computational cost of the FFT is predominant in the both algorithm, these algorithms have similar order of computational costs.…”

“…Taking into account the complexity of each term in (20), the overall Computational Complexity (CC) is MN(2 + log 2 N) + k |P k | log 2 |P k | + |P| for M frames using the optimal algorithm in [34] and MN(2 + log 2 N) + 2|P| using the suboptimal algorithm in [35]. For example in [24], authors have considered a case with M = 24, 30 pilots pairs The desired system is active; 8: else if T (Y, P) < η det then 9: The desired system is inactive; 10: end if and N = 2048. In this case, the overall complexity of their algorithm is approximately 5.4 × 10 5 MAC where each MAC consists of one complex multiplication and one addition.…”

“…Unfortunately such a technique add overhead, reduce network capacity and are not applicable for the existing OFDM networks. Finally, in [24][25][26], authors proposed to exploit the pilot patterns which is a signature already embedded in many existing OFDM networks (for example in WiFi, WiMAX, LTE). These pilot signals are transmitted for other reasons such as synchronization [27][28][29] and channel estimation [30][31][32].…”

“…Unfortunately, the technique proposed in [26] is dedicated only to LTE signals. The first proposed method in [24] relies on the periodic redundancy often induced between pairs of pilot symbols. The second proposed method is dedicated to the case where the pilots are modulated by a pseudo random sequence, authors in [24] proposed to exploit the properties of the pseudo random generator.…”

“…The first proposed method in [24] relies on the periodic redundancy often induced between pairs of pilot symbols. The second proposed method is dedicated to the case where the pilots are modulated by a pseudo random sequence, authors in [24] proposed to exploit the properties of the pseudo random generator. These methods require the knowledge of the position of the pilots in time and frequency, and are only applicable if these pilots have some known redundant relation (either in the form of known correlation or in the form of a pseudo random sequence), which make them not applicable in all cases.…”