OFDMA Uplink Frequency Offset Estimation with Multi-Access Interference Mitigation
نویسندگان
چکیده
In this paper, we consider the frequency offset estimation for Orthogonal Frequency-Division Multiple Access (OFDMA) uplink (UL) transmissions. We first analyze the negative effect of Multi-Access-Interference (MAI) on OFDMA UL, and then propose two interference reduction/elimination methods, i.e., the Reduced-Rank-Projector (RRP) and Shift-Sampling-Projector (SSP) methods, to eliminate/reduce the heavy MAI due to the frequency offsets. Finally, we propose a new training sequence group named the Round-Robin Training Sequence Group (RRTSG), which has a high interference mitigation capabilities for OFDMA UL transmission. The Cramer-Rao Lower Bound (CRLB) for an unbiased frequency offset estimator in a Multiple Access (MA) system is also derived. Numerical results show that the proposed methods are suitable to eliminate/mitigate the effect of the frequency offset on OFDMA UL transmission.
منابع مشابه
Joint Timing Synchronization and Channel Estimation in Uplink of Time Domain Synchronous OFDMA
Multiple users TDS-OFDMA has been proposed based on time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM). This multiple access schemes used mostly in mobile broadband wireless access scheme in uplink transmission due to the multiple user interference in timing offset and frequency offset problems. In this paper we are focusing on timing synchronization and channel estim...
متن کاملFuzzy Based Adaptive Weighted Multiuser Interference Cancellation in Ofdma Systems
Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user version of the Orthogonal frequency-division multiplexing (OFDM). OFDMA is used in the mobility mode of IEEE 802.16 WirelessMAN Air Interface standard, commonly referred to as WiMAX. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to individual users [1], [2]. The performance of these systems depend o...
متن کاملAdaptive Weighted Multiuser Interference Cancellation in Ofdma Systems
Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user version of the Orthogonal frequency-division multiplexing (OFDM). OFDMA is used in the mobility mode of IEEE 802.16 WirelessMAN Air Interface standard, commonly referred to as WiMAX. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to individual users [1], [2]. The performance of these systems depend o...
متن کاملAnalysis and Suppression of MAI in WiMAX Uplink Communication System with Multiple CFOs
Nowadays, OFDMA (Orthogonal Frequency Division Multiple Access) technique has been used in WiMAX communication system to achieve very high data rate as well as multi-user service. However, similar with other OFDM-based systems, OFDMA system is very sensitive to frequency synchronization errors, especially in the uplink communications where different users always have different CFOs (Carrier Fre...
متن کاملGravitational Search Algorithm for Low Complexity Carrier Frequency Offset Estimation in Uplink OFDMA Systems
Orthogonal frequency division multiple access (OFDMA) systems in the uplink suffer from multiple access interference (MAI) due to their high sensitivity to frequency misalignments between different users. Moreover, carrier frequency offset (CFO) is a major factor that degrades performance of the OFDMA system. As the maximumlikelihood (ML) estimator is impractical in this context, we introduce a...
متن کامل