Multiple transmitters for performance improvement of downlink indoor optical wireless communications through dispersive channels | |
| Author | Supreeya Pakpinpetch |
| Call Number | AIT Thesis no.TC-06-07 |
| Subject(s) | Wireless communication systems Infrared technology |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-06-07 |
| Abstract | This thesis investigates downlink indoor optical wireless transmission. A transmitter is assumed to be a Lambertian source radiating light. The transmit signal is modulated using 4-Pulse Position Modulation (PPM). Uniform ambient light noise, modeled as additive white Gaussian noise (AWGN), is added to transmit signal when passing through a dispersive channel. Ray tracing is used to compute channel impulse response. To deal with intersymbol interference (ISI), maximum likelihood sequence estimator is used as equalizer. The transmission performance is evaluated by the bit error rate (BER). To achieve 10-4 BER, required transmit powers are found from various transceiver locations. Simulation models are used to study the performance improvement from the use of multiple transmitters while using a single-input receiver. A cubic room with size 5mx5mx5m is used as a symmetric case, whereas a room with size 10mx5mx4m is used as an asymmetric case. To cover communication areas with low transmit power, limited numbers of locations for one and two transmitters are investigated. For a cubic room, one transmitter at center of the ceiling requires the least total transmit power. For an asymmetric room, two transmitters on the ceiling at distance 6m apart from each other reduces the power requirement from that of one transmitter by around 2 dBm for the same BER at 104. Based on the best transmitter locations obtained from simulations, we identify the maximum supportable bit rates subject to eye-safety power limitation. The transmit bit rate of 140 Mbps with power of 24.4 dBm is the maximum rate for room size 5mx5mx5m with one transmitter on center of the ceiling. The transmit bit rate of 40 Mbps with power of 23.8 dBm is the maximum rate for room size 10mx5mx4m with two transmitters on the ceiling |
| Year | 2006 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-06-07 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Poompat Saengudomlert; |
| Examination Committee(s) | Ahmed, Kazi M.;Rajatheva, R.M.A.P. ; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2006 |