Fig 3 - uploaded by Pau Closas
Content may be subject to copyright.
Comparison of PSDs for MSK, OFDM, BPSK, BOC, and MBOC modulations. The relative power attenuations between the first side lobe and the main lobe (in dB) are also listed in the figure
Source publication
The objective of this work is to investigate the performances of orthogonal frequency division multiplexing (OFDM) and minimum frequency shift keying (MSK) modulations as potential future global navigation satellite systems (GNSS) signal modulation schemes. MSK is used in global system for mobile communications because of its spectral efficiency, w...
Contexts in source publication
Context 1
... use simulation results to illustrate the spectrum effi- ciency and adjacent channel interference (ACI) suppres- sion properties of MSK and OFDM modulations based on the ACF and PSD expressions described in the above subsection. Figure 3 shows the PSD for MSK, OFDM, and several BPSK, BOC, and MBOD signals. BPSK(1), BPSK(2), and BPSK(10) are modulations used in GPS L1 CA, Beidou B1, and GPS L5 signals, respectively, while BOC(1,1) and MBOC(6,1,1/11) are used in Galileo E1 signal. ...
Context 2
... frequency shift keying modulation is a con- stant envelop signal with phase continuity during bit tran- sitions. The phase continuity makes the PSD compact, falling off rapidly with increasing frequency as shown in Fig. 3. This property makes MSK a spectrum efficient modulation scheme compared to other signals. Moreover, it can be seen from Fig. 3 that the main lobe of an MSK signal is larger than that of a BPSK and OFDM signals, implying that most of the energy of MSK modulation is concentrated within the main lobe, while the side lobes magnitude ...
Context 3
... frequency shift keying modulation is a con- stant envelop signal with phase continuity during bit tran- sitions. The phase continuity makes the PSD compact, falling off rapidly with increasing frequency as shown in Fig. 3. This property makes MSK a spectrum efficient modulation scheme compared to other signals. Moreover, it can be seen from Fig. 3 that the main lobe of an MSK signal is larger than that of a BPSK and OFDM signals, implying that most of the energy of MSK modulation is concentrated within the main lobe, while the side lobes magnitude decreases rapidly. Therefore, it is less vulnera- ble to ACI caused by other closely spaced signal sources in the frequency domain. ...
Context 4
... it is less vulnera- ble to ACI caused by other closely spaced signal sources in the frequency domain. Figure 3 also shows that the side lobes of MSK, OFDM, BPSK(1), BPSK(10), BPSK(2), BOC (1,1), and MBOC (6,1,1/11) are about 23, 16.3, 13.4, 13.4, 13.3, 10.6, and 11.4 dB lower than their corresponding main lobes, respectively. Therefore, both the MSK and OFDM modu- lations have superior spectrum efficiency compared with the other legacy modulations shown in the figures. ...
Citations
... In [10], the performance of orthogonal frequency division multiple access (OFDMA), localized FDMA (LFDMA), and interleaved FDMA (IFDMA) were compared under flat fading channel considering nonlinear distortion and asynchronous inter block interference (IBI), which showed that LFDMA outperformed the other two waveforms under asynchronous scenarios. The authors of [11] investigated the performances of OFDM and minimum frequency shift keying (MSK) modulations as potential global navigation satellite systems (GNSS) signal modulation schemes, the results showed that OFDM demonstrated promises as a viable GNSS modulation with larger bandwidths. The performance assessment of 5G NR physical layer aspects for satellite applications was carried out in [12], which showed that OFDM can fulfill the communication requirements in scenarios with flat fading and low receiver speed. ...
Non terrestrial network (NTN) has been regarded as an important component of beyond 5G communication. The 3rd Generation Partnership Project (3GPP) has officially started studies on NTN for the purpose of integrating satellites with New Radio (NR) terrestrial networks. However, the NR defined orthogonal frequency division multiplexing (OFDM) waveform is susceptible to doubly selective fading and nonlinear distortions in the NTN uplink, thus leading to severe performance loss. In this paper, a type of block scalable OFDM (BS-OFDM) waveform is proposed, which has modified subcarrier and sub-symbol segmentation when compared to the conventional NR defined OFDM.With our proposed framework, block scalable discrete Fourier transform spread OFDM (BS-DFT-s-OFDM) and block scalable orthogonal time frequency space (BS-OTFS) can also be implemented. To obtain a comprehensive understanding of different waveforms, performance metrics concerning peak to average power ratio (PAPR), total degradation (TD), bit error rate (BER), and complexity are presented. The simulation results demonstrate that the proposed block scalable waveforms can obtain better performance and lower complexity than existing NR waveforms in different NTN uplink scenarios, and can therefore be promising candidate waveforms for NR NTN.
... Actually, researchers primarily focus on achieving navigation functionality within communication signals in the NavCom signals study [6][7][8][9][10][11][12][13][14]. So far, however, very little attention has been paid to treating communication and navigation as a whole, resulting in the full integration of communication and navigation functions having not been thoroughly explored. ...
... Thus, traditional security authentication schemes, such as OSNMA and Chimera, cannot recognize repeater spoofing interference. Actually, researchers primarily focus on achieving navigation functionality within communication signals in the NavCom signals study [6][7][8][9][10][11][12][13][14]. So far, however, very little attention has been paid to treating communication and navigation as a whole, resulting in the full integration of communication and navigation functions having not been thoroughly explored. ...
Low Earth Orbit (LEO) satellite communication systems typically achieve identity authentication through the encryption and decryption of two-way information, which requires complex key management systems. In contrast, the integration of navigation and communication (NavCom) signals provides novel opportunities for physical observation and authentication solutions due to its measurement functions. This paper introduces a novel signal authentication scheme based on twice two-way satellite time transfer (TWSTT) for LEO satellite systems. It leverages the non-mutated nature of the clock difference to ascertain the legitimacy of the signal by measuring the clock difference of signals at different instances. Unlike traditional authentication methods, this approach directly exploits the temporal and spatial characteristics of the signal, negating the necessity for intricate authorization key systems. Additionally, it adeptly tackles the challenges posed by spoofing interference. The performance analysis indicates that this scheme can achieve a high detection probability for the repeater spoofing signal in the low carrier-to-noise ratio conditions.
... However, current GNSS receiver techniques cannot easily satisfy next-generation positioning, navigation, and timing (PNT) performance, due to the intrinsic mechanism of GNSS electromagnetic waveforms. For instance, unlike LTE/5G wireless communication signals, having orthogonal frequency division multiple access (OFDMA) and substantial transmission power [3,4], GNSS signals are transmitted at the same frequency. Each signal channel is divided through the code division multiple access (CDMA). ...
Many multi-sensor navigation systems urgently demand accurate positioning initialization from global navigation satellite systems (GNSSs) in challenging static scenarios. However, ground blockages against line-of-sight (LOS) signal reception make it difficult for GNSS users. Steering local codes in GNSS basebands is a desirable way to correct instantaneous signal phase misalignment, efficiently gathering useful signal power and increasing positioning accuracy. Inertial navigation systems (INSs) have been used as effective complementary dead reckoning (DR) sensors for GNSS receivers in kinematic scenarios, resisting various forms of interference. However, little work has focused on whether INSs can improve GNSS receivers in static scenarios. Thus, this paper proposes an enhanced navigation system deeply integrated with low-cost INS solutions and GNSS high-accuracy carrier-based positioning. First, an absolute code phase is predicted from base station information and integrated solutions of the INS DR and real-time kinematic (RTK) results through an extended Kalman filter (EKF). Then, a numerically controlled oscillator (NCO) leverages the predicted code phase to improve the alignment between instantaneous local code phases and received ones. The proposed algorithm is realized in a vector-tracking GNSS software-defined radio (SDR). Results of the time-of-arrival (TOA) and positioning based on real-world experiments demonstrated the proposed SDR.
... However, current GNSS receiver techniques are uneasy to achieve a next-generation positioning, navigation, and timing (PNT) performance due to the intrinsic mechanism of GNSS electromagnetic waveforms. For instance, unlike LTE/5G wireless communication signals with an orthogonal frequency division multiple access (OFDMA) and substantial transmission power Liu et al. [2014], Cimini [1985], the GNSS signals are transmitted at the same frequency. Differently, each signal channel is divided through the code division multiple access (CDMA). ...
Many multi-sensor navigation systems urgently demand accurate positioning initialization from global navigation satellite systems (GNSSs) in challenging static scenarios. However, ground blockages against line-of-sight (LOS) signal reception make it difficult for GNSS users. Steering local codes in GNSS basebands is a desiring way to correct instantaneous signal phase misalignment, efficiently gathering useful signal power and increasing positioning accuracy. Besides, inertial navigation systems (INSs) have been used as a well-complementary dead reckoning (DR) sensor for GNSS receivers in kinematic scenarios resisting various interferences since early. But little work focuses on the case of whether the INS can improve GNSS receivers in static scenarios. Thus, this paper proposes an enhanced navigation system deeply integrated with low-cost INS solutions and GNSS high-accuracy carrier-based positioning. First, an absolute code phase is predicted from base station information, and integrated solution of the INS DR and real-time kinematic (RTK) results through an extended Kalman filter (EKF). Then, a numerically controlled oscillator (NCO) leverages the predicted code phase to improve the alignment between instantaneous local code phases and received ones. The proposed algorithm is realized in a vector-tracking GNSS software-defined radio (SDR). Real-world experiments demonstrate the proposed SDR regarding estimating time-of-arrival (TOA) and positioning accuracy.
... It can be seen in Figure 7 that, compared to the sidelobes of the normalized p spectral density, both OFDM (64) and NSCC (19) have an excellent main lobe bandw performance, and both have remarkable main-sidelobe ratios. (PSR). ...
... (PSR). Although the lobe bandwidth of NSCC (19) is slightly better than that of OFDM (64), the latter is a s scheme that is widely used in wireless communication, while the OFDM signal sc has a natural compatibility and interoperability. The authors are relatively more opt tic about the theoretical feasibility and engineering application prospects of the OFDM-PM signal scheme. ...
... Gabor bandwidth (also called RMS bandwidth) is a core indicator that is comm used to test the tracking accuracy of receivers. It can be defined as: Figure 7. CE-OFDM-PM (64) is compared with NSCC (19) in terms of normalized power spectral density. In the normalized PSD, the scarlet solid line is significantly larger than the blue, and the former supports the multiplexing of more users in the same bandwidth and suppresses the power generated by other signals at the same band. ...
The mega-launch of low Earth orbit satellites (LEOs) represents a critical opportunity to integrate navigation and communication (NavCom), but first, challenges related to signal design must be overcome. This article proposes a novel signal scheme named CE-OFDM-PM. Via research on the in-band or adjacent band, it was found that the proposed signal scheme was suitable for S-band and had a wide normalized power spectrum density (PSD), high peak-to-side lobe ratio (PSR), and multiple peaks in autocorrelation. In an analysis of the simulation performance evaluation in navigation and communication, it is found that the proposed signal scheme has the potential for high accuracy, a code tracking accuracy of up to 0.85 m, a small mutual influence between the proposed signal scheme and other schemes, excellent anti-interference properties, and a better performance at both short and long distances in terms of its anti-multipath capability. Furthermore, the proposed signal scheme shows the ability to communicate between satellites and the ground and is outstanding in terms of its bit error rate (BER), CNR, and energy per bit to noise power spectral density ratio (Eb/N0). From the technical, theoretical, and application perspectives, our proposed signal scheme has potential as an alternative scheme in future BDS, PNTs, and even 5G/B5G.
... On one hand, more spectrally compact shaping pulse functions such as rectangular, raised cosine and so on, are widely used in low order modulation. For example, minimum shift keying (MSK), a form of quadrature phase shift keying (QPSK) with halfsinusoidal pulse shaping, is treated as potential future global navigation satellite systems (GNSS) signal modulation schemes in [9]. Gaussian filtered minimum shift keying (GMSK) with a filter having Gaussian impulse response prior to frequency modulation of the carrier is provided as the signal option for SATCOM in [10]. ...
The development of satellite communication (SATCOM) puts forward demanding requirements for the modulation methods' spectral efficiency (SE) which is mainly subject to the pulse shaping and the utilisation of signal space. To date, there has rare consideration on the modification of high order phase shift keying (HOPSK) to gain higher SE in this literature. In this work, shaped offset 8PSK (SO8PSK) is developed which splits 8PSK bit transmission into three offset paths and then loads the shaping pulse onto them. The obtained modulation with continuous constrained phase and constant envelope is shown to increase the SE compared to 8PSK by about 43% and is applicable for the nonlinear and band‐limited SATCOM environment. To address the HOPSK inherent complexity, a simplified receiver is provided to reduce about two‐third matched filters. Additionally, the iterative encoding of SO8PSK is presented and it is used as the inner code of serial concatenated coding (SCC) . This modification method can be seen as a starting point to the better use of HOPSK for SATCOM.
... SSMSK is one special case of FSK modulation, but it can also be expressed as the form of OQPSK (Offset Quadrature Phase Shift Keying). The time-domain expression is expressed as follows [14,15]: (see (3)) , where A is the amplitude, d I t , d Q t are separately the data bit on I channel and Q channel, a m , b n are the symbols on each channel, and in this part they mean the spread spectrum codes, T s is the time length of symbols and p t is expressed as follows: ...
BPSK is the basis of current GNSS (Global Navigation Satellite System) signals. BDS (Beidou navigation satellite system) RDSS (Radio Determination Satellite Service) system also adopts BPSK to realize communication and ranging simultaneously. To realize higher system capacity, RDSS signals overlap in time and frequency domain. The signal performance is heavily determined by the MAI (Multiple Access Interference) between overlapping signals. In this paper, SSMSK (spread spectrum MSK) is proposed. The signal performance is investigated under four conditions considering the main lobe bandwidth and the receiver bandwidth. The maximum number of overlapping signals for SSMSK is 11.7% higher than BPSK when the receiver bandwidth is for the side subcarrier. And the value is 10.6% when the receiver bandwidth is. SSMSK can be received utilizing BPSK local signal. When the receiving bandwidth is 2Rc, the correlation peak of SSMSK_BPSK is identical to BPSK. The tracking accuracy of SSMSK is higher than BPSK when the correlation interval is between 0.2‐1 chips. The accuracy of SSMSK_BPSK is higher than BPSK when the correlation interval is 0.5 chips. The disadvantage of SSMSK is larger quantization word length. SSMSK is a better modulation for RDSS based on the comprehensive performance.
... The ranging performance is evaluated by the theoretical accuracy of the time-delay estimation, which can be represented by the Gabor bandwidth [Liu+14], considered as an alternative interpretation of the Cramér-Rao lower bound. The Gabor bandwidth is given as: ...
... Note that the greater the Gabor bandwidth is, the better performance in terms of codetracking accuracy [Liu+14]. ...
... Presently the Global Navigation Satellite System (GNSS) technology has grown rapidly all around the world and many countries are trying their best to use their own navigation satellite systems to cope up. Because of this, the Radio Frequency (RF) band which is currently allocated for GNSS is not adequate for providing several planned services for the future due to congestion in the current spectrum especially in E1 and L1 bands [Liu, Liang, Morton et al. (2014); Betz (2013)]. Consequently, there is a need for a new frequency band to be used for the satellite navigation systems in addition to L Band [Svaton (2015)]. ...
A good design of LNA for S band satellite navigation receivers and 4G LTE wireless communication system has been implemented in this paper. Due to increased congestion in the present L band, the S Band frequency from 2483.5-2500 MHz has been allocated for the future satellite navigation systems. For this purpose ATF-34143 amplifier (pHEMT) having high electron mobility and fast switching response has been chosen due to its very low Noise Figure (NF). The amplifier has been designed having bandwidth of 0.8 GHz from 1.8-2.6 GHz. Because of the large bandwidth, the amplifier could serve many wireless communication applications including 4G LTE mobile communication at 2.1 GHz. The design was implemented using the micro strip technology offering extremely low noise figure of 0.312 dB and 0.377 dB for 2.1 GHz and 2.49 GHz respectively. The gain of the amplifier was low and found to be 10.281 dB and 9.175 dB. For the purpose of increasing the gain of an amplifier, the proposed LNA design was then optimized by using Wilkinson Power Divider (WPD). The Balanced LNA design using WPD offered very low noise figure of 0.422 dB and 0.532 dB respectively and the gain was considerably increased and was found to be 20.087 dB and 17.832 dB respectively against 2.1 GHz and 2.49 GHz. Simulations and measurements were taken in Agilent Advanced Design System (ADS) software. The suggested LNA can be used for a variety of wireless communications applications including the future S band satellite navigation systems.
... The ranging performance is evaluated by the theoretical accuracy of the time-delay estimation, which can be represented by the Gabor bandwidth [10] considered as an alternative interpretation of the Cramér-Rao lower bound [10]. Therefore the greater the Gabor bandwidth is, the better the performance in terms of code-tracking accuracy. ...
... The ranging performance is evaluated by the theoretical accuracy of the time-delay estimation, which can be represented by the Gabor bandwidth [10] considered as an alternative interpretation of the Cramér-Rao lower bound [10]. Therefore the greater the Gabor bandwidth is, the better the performance in terms of code-tracking accuracy. ...
... Gabor bandwidth = √∫ 2 ( ) /2 − /2 [10] (5) ...
