The paper analyzes channel impulse response (CIR) estimation using aperiodic transmit sequences and a receiver which removes carrier frequency offset (CFO) after correlation. It is shown that when there are guard intervals between the transmit sequences longer than the CIR, a class of sequence sets previously introduced can be applied to achieve CIR estimation without any correlation sidelobes for an arbitrary CFO. As having these guard intervals may be viewed as a waste of on-air time, the same problem is solved when they are eliminated by introducing a new class of sequence blocks. Furthermore, for binary sequence blocks, it is shown that by careful construction of the base Hadamard matrices the minimum sizes of these blocks can be halved. The price to pay are the correlation sidelobes that are minimized but generally are not zero anymore, except for zero CFO and a couple of small Hadamard matrix sizes.

The paper introduces the periodic ambiguity function (PAF) of the preamble code as a tool in designing periodic synchronization preamble. It is shown that in the considered low-complexity receiver architecture characteristics of the PAF, namely, sidelobes peak level and main lobe phase, play an important role in the quality of the channel estimation. Furthermore, it is shown that these PAF characteristics vary considerably with the circular shift of the preamble code and care should be taken when selecting both preamble codes and corresponding circular shifts. This is done on an example of the preamble design for high pulse repetition frequency (HPRF) mode of the upcoming IEEE 802.15.4z standard amendment for enhanced ultra wideband (UWB) physical layers (PHYs) and associated ranging techniques. Similar analysis is carried-out on the preamble codes already specified in the high-rate pulse repetition frequency (HRP) UWB PHY of the IEEE 802.15.4-2015 standard.

Precise digital estimation of Carrier Frequency Offset (CFO) between transmitter and receiver is an inherent part of the frame reception in some coherent radio architectures, e.g., Decawave’s IEEE 802.15.4a-compliant Ultra-Wideband (UWB) DW1000 integrated circuit. There, CFO direct translate to the relative clock offset between the transmitter and the receiver. The paper shows how such CFO estimate can be used in several radio localization schemes with a low number of frames exchanged in order to reduce significantly the ranging error caused by the clock offsets. By using the techniques introduced in the paper these schemes become practical for significant clock offset values. The radio localization schemes examined are Single-Sided Two-Way Rang (SS-TWR), Asynchronous Time Difference of Arrival (A-TDOA) and SS-TWR with A-TDOA extension.

The paper describes principles of angle of arrival estimation using an anchor and a tag which are built around Decawave's DW1000 impulse radio ultra-wideband IC. Typical experimental results are provided that show the performance of Decawave's AOA demo kit based on this architecture.

The paper presents a method of antenna array pattern shaping, i.e. beamforming, for Impulse Radio Ultra-Wideband (IR-UWB) correlation beamformers. The method is based on Second Cone Programming (SOCP) and allows for several parameters of shaped pattern to be simultaneously optimized; it allows for arbitrary antenna array geometry as well as for arbitrary UWB frequency-dependent radiation pattern to be considered. Before the method is described, the paper introduces time domain model of wideband antenna array along with IR-UWB correlation beamforming structure. Numerical examples using a realistic UWB antenna as an array element are also provided.

The paper presents methodology for analyzing compliance of Impulse Radio Ultra-Wideband (IR-UWB) communications systems with regulatory limits specified by US Federal Communications Commission (FCC). First, discrete spectral component that reduce Effective Isotropic Radiated Power (EIRP) in IR-UWB spectrum are analyzed in an exemplary IRUWB system. After that, a minimal Pulse Repetition Frequency (PRF) in an IR-UWB system at which EIRP spectrum level does not have to be reduced in order to meet peek power regulatory constrain is derived for two different modulations; namely, On-Off Keying (OOK) and Binary Phase Shift Keying (BPSK).

The paper proposes a novel Trellis Coded Modulation (TCM) scheme for coherent Impulse-Radio Ultra-Wideband (IR-UWB) IEEE 802.15.4a communications that, in comparison with the current IEEE 802.15.4a IR-UWB communications scheme, is able to reduce energy per bit consumed in the receiver two times with approximately 2 dB performance loss. Furthermore, changed in the IEEE 802.15.4a coherent IR-UWB radio required to implement proposed TCM are minimal. Downside is that the proposed TCM scheme cannot be detected by non-coherent receivers. Discussion starts by looking at the current IEEE 802.15.4a IR-UWB coding and modulation scheme as a rudimentary TCM. After that, a transition is made through the TCM framework from the current IEEE 802.15.4a IR-UWB coding and modulation scheme to the proposed one.

The paper investigates chirp pulse compression as a signal dimension reduction technique in non-coherent impulse-radio ultra-wideband (IR-UWB) communications. Two common types of non-coherent IR-UWB detection are considered, energy detection of IR-UWB pulse position modulated (PPM) symbols and sample-wise differential detection of differential phase shift keying (DPSK) IR-UWB symbols, as well as a newly introduced sample-wise differential detection of IR-UWB PPM symbols. A common problem with these low-complexity IR-UWB detection schemes is poor performance when the dimension of the symbol in detection is high, which is usually the case at low data rates and is especially pronounced in interference environments. Chirp pulse compression mitigates this problem by reducing the dimension of the symbol in detection along with very small fading factor, which also lowers the computational complexity in the case of digital implementation. In the analytic part of the paper, we develop a closed-form expression for the bandwidth and dimension of the signal after the chirp pulse compression, which was lacking before. Furthermore, a closed-form expression of the bit error probability in white noise with the above detection schemes is also given. In the numerical part of the paper, we compare the performance with and without chirp pulse compression of the above modulation/detection pairs in noise and interference environments.

The paper introduces an efficiency factor useful for the pattern synthesis of the transmitting antenna arrays with each array element being fed by its own power amplifier, active power of which is limited. The factor is based on the L∞ norm of the active powers at the elements' feeds with mutual coupling between elements taken into account. Two Second Order Cone Programming (SOCP) based methods of the array radiation pattern synthesis that maximize this factor are formulated. After that, minimax array radiation pattern synthesis method with this factor constrained is described. As an illustration of its features, the method is applied on the pattern synthesis of a 15-element antenna array model obtained from the method of moments EM simulation.

The paper analyses several modulation and detection pairs for Impulse-Radio Ultra-Wideband (IR-UWB) Body Area Networks (BANs). First, transceiver architectures with and without chirp pulse compression are described. After that, exact expressions for the bit error probabilities in noise are given. At the end, numerical analysis is performed that includes performances in noise and performances in multiple access interference, which are especially critical for medical IR-UWB BANs.

In this paper, we propose a novel type of Impulse Radio Ultra-Wideband (IR-UWB) beamforming structure that we named a chirp beamformer. It represents an alternative to the well-known correlation beamforming paradigm. The chirp beamformer uses a chirp pulse as a symbol waveform. In comparison with a correlation beamformer, the chirp beamformer requires considerably lower timing resolution in cases where the IR-UWB symbol consists of a relatively long single uninterrupted waveform, as in the mandatory modes of two of the IEEE 802.15 IR-UWB standards, namely IEEE 802.15.4a-2007 and IEEE 802.15.6-2012. Furthermore, the bandwidth of the signal that the chirp beamformer generates in the baseband is considerably lower than in the case of the correlation beamformer. Hence, in the case of digital baseband signal generation, the chirp beamformer requires a considerably lower sampling rate than the correlation beamformer. A method for shaping the beam pattern of the chirp beamformer is also described. All concepts introduced are illustrated by numerical examples.

In this paper we present analysis of the physical layer performance of an system with the On-Off Keying (OOK) modulation. We begin with developing a system model with describing three different receiver architectures; namely, coherent quadrature sampling receiver, envelope sampling receiver and energy detection receiver. Performances of these receiver architectures are compared in noise and Multiple Access Interference (MAI). Furthermore, the performance comparison is made in three different phases of the packet reception: preamble synchronization, Synchronization Frame Delimiter (SFD) detection and payload detection.

The paper describes technique for differential detection of Impulse Radio Ultra-Wideband (IR-UWB) Pulse Position Modulated (PPM) symbols. An expression for probability of error in noise is derived. The numerical results show the method's performance enhancement compared to the energy detection in noise and considerable performance enhancement in multiuser interference. The method is applicable to the mandatory mode of the IEEE 802.15.6 Body Area Network (BAN) IR-UWB standard.

This paper investigates possible amendment of the IEEE 802.15.6 standard for Body Area Network (BAN). Particularly, we study amending the IEEE 802.15.6 Impulse-Radio Ultra-Wideband (IR-UWB) DPSK Physical Layer (PHY) through adding data rates lower than what is currently both the lowest and mandatory data rate of this PHY. The motivation for this study is enhancing link margin and, more importantly, enhancing PHY's multi-BAN interference resistivity, crucial in medical applications of IEEE 802.15.6 BAN. Three different possibilities of adding lower data rates are considered. The first is increasing transmitted waveform duration and thus symbol rate; the second is introducing a spreading sequence and using current mandatory data rate symbols as chips; the third is introducing an inner convolution code for concatenation with the existing BCH(63,51) block code. Performances of these communication schemes are studied in multi-BAN interference.

The paper analyses performances of the two lowest data rates of impulse-radio ultra-wideband DPSK physical layer of recently published IEEE 802.15.6 Body Area Networks standard. Two receiver architectures suitable for the reception of symbols with signal structure described in specification of this physical layer, namely duty-cycled sampling receiver and chirp receiver, are introduced. Then, performance of these receiver architectures are analyzed through probabilities of error in different phases of packet reception. Analysis has been performed in the presence of different types of interference; namely frequency modulated ultra-wideband, WiMax and other co-located IEEE 802.15.6 impulse-radio ultra-wideband devices.

The paper investigates benefits of using chirp pulse compression in non-coherent Impulse-Radio Ultra-Wideband (IR-UWB) communications. Furthermore, we develop closed form expression for bandwidth and dimension of the signal after the chirp pulse compression that was lacking before. Two usual types of non-coherent IR-UWB detection are considered - energy detection of PPM-modulated symbols and sample-wise differential detection of DPSK-modulated symbols. These detection schemes show deterioration of bit error probability performance with an increase of the dimension of the signal in detection. The performance of the aforementioned detection schemes improves significantly when chirp pulse compression is applied, i.e. when dimension of the signal in detection is reduced. As we show, this performance enhancement happens in noise as well as in multi-user interference.

In this paper, several aspects of IEEE 802.15.6 DPSK IR-UWB physical layer for usage in the medical BAN are examined. First, the types of the waveforms used in the standard are given. After that we describe the packet structure. We also provide mathematical analysis of two receiver structures: the duty-cycled sampling receiver and the chirp receiver is provided with suitable digital detection methods definitions and analysis. The paper continues with developing a method of synchronisation for preamble structure described in the standard draft together with the synchronisation frame delimiter (SFD) detection method. Preamble structure itself is discussed together with offering an alternative that has better performance with less computational complexity. The performances of receivers designed according to specifications given in the paper are simulated in multi-BAN environments in order to verify robustness of such BAN devices to interference from co-located BANs, essential for the application of this physical layer in the medical BAN.

The paper analyses performances of the mandatory mode of Body Area Network IEEE 802.15.6 Impulse-Radio Ultra-Wideband DPSK physical layer in different types of interference; namely Frequency Modulated Ultra-Wideband, WiMax and other co-located IEEE 802.15.6 Impulse-Radio Ultra-Wideband devices. Interference performance of two receiver architectures suitable for the specification of this physical layer: duty-cycled sampling receiver and chirp receiver are analyzed through probabilities of error in different phases of packet reception.

The paper develops a method of synchronization for synchronization header (SHR) structure described in the draft of IEEE 802.15.6 standard for body area network (BAN) and its Impulse-Radio Ultra-Wideband (IR-UWB) physical layer (PHY) with differential phase modulation. Uniqueness of this PHY is that transmitted waveform shape is not known to the receiver at the time of synchronization and therefore classic synchronization methods based on correlation cannot be employed. Based on the developed synchronization method, synchronization performances with the different SHR structures are evaluated and solutions are suggested for the SHR structure described in the standard.