Indoor optical wireless systems employing dual header pulse interval modulation (DH‐PIM)

Abstract

SUMMARYThis paper assesses the performance of dual header pulse interval modulation (DH-PIM) over indoor optical wireless systems. DH-PIM being anisochronous scheme offers a built-in symbol synchronization capability. Theoretical and simulation results demonstrate that DH-PIM offers shorter symbol length, improved transmission rate and bandwidth requirement and a comparable power spectral density profile compared with digital pulse interval modulation (DPIM) and pulse position modulation (PPM) schemes.It is shown that DH-PIM 2 ; with wider pulse duration is the preferred option when the available channel bandwidth is limited and higher optical power is tolerable. Whereas DH-PIM 1 ; with narrower pulse width, exhibits comparable power requirements but a marginally higher bandwidth compared with DPIM, and is also more bandwidth efficient than PPM at the cost of increased power requirement. However, at higher bit resolutions, i.e. M57; DH-PIM 1 is both bandwidth and power efficient compared with PPM. Error rate analysis show that DH-PIM offers improved packet error rate compared with on-off-keying (OOK) and DPIM, but marginally inferior as compared with PPM. The power requirement and penalty due to intersymbol interference for non-dispersive and dispersive channels is analysed and the results show that for given parameters, DH-PIM requires marginally higher optical power compared with PPM and DPIM, but it supports the same bit rate at much less bandwidth requirement.

Convolutional coded dual header pulse interval modulation for line of sight photonic wireless links

“…Instead the SER and packet error rate (PER) are adopted to measure the error performance, a characteristic unique to the anisochronous pulse time modulation schemes. Assuming that there is no bandwidth 6 limitation imposed by the channel, and H 0 and H 1 are equally likely, the probability of symbol and packet errors for the DH-PIM for a LOS link configuration is given by [16]:…”

“…In fact the 3 dB bandwidth of a channel can be less than 30.4 MHz, limiting the unequalized bit rate to few Mbps [2,12]. Different modulation techniques have been suggested and investigated for a number of applications; among them are on-off keying (OOK), PPM [13], differential PPM (DPPM) [14], digital pulse interval modulation (DPIM) [15], DH-PIM [16] and differential amplitude pulse-position modulation (DAPPM) [17]. OOK is the most basic and widely 3 investigated, offering a high bandwidth efficiency at the cost of a low power efficiency.…”

“…DPIM, DH-PIM and DAPPM are anisochronous modulation schemes offering built-in symbol synchronisation capabilities and improvement in bandwidth and power efficiencies compared to the PPM and OOK, respectively. In terms of transmission capacity and bandwidth, the DH-PIM offers the best choice compared to the PPM and DPIM at the cost of a more complex symbol header structure and higher power requirement for a given bit error rate (BER) performance [16]. DAPPM is a combination of DPPM and pulse amplitude modulation (PAM), offering advantages over PPM, DPPM and DH-PIM in terms of bandwidth requirements, transmission capacity, and the peak-toaverage power ratio [17].…”

“…In [16] the detailed analysis of a standard un-coded DH-PIM scheme has been reported. In this paper, we introduce the CC-DH-PIM scheme and carry out full theoretical analysis supported by computer simulations to demonstrate that the error performance can be significantly improved compared to the un-coded DH-PIM.…”

Performance evaluation of turbulence‐accentuated interchannel crosstalk for hybrid fibre and free‐space optical wavelength‐division‐multiplexing systems using digital pulse‐position modulation

“…optical power requirement efficiency which is necessary in complying with eye safety limitations [22], and also provides better error rate performance [21]. Furthermore, at lower coding level (for example at coding level of 2 or 1), DPPM bandwidth efficiency is comparable to that of other digital pulse modulation schemes as shown by results in [22].…”