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Papers by Jishu Das Gupta

Temporal variations caused by pedestrian movement can significantly affect the channel capacity o... more Temporal variations caused by pedestrian movement can significantly affect the channel capacity of indoor MIMO-OFDM wireless systems. This paper compares systematic measurements of MIMO-OFDM channel capacity in presence of pedestrians with predicted MIMO-OFDM channel capacity values using geometric optics-based ray tracing techniques. Capacity results are presented for a single room environment using 5.2 GHz with 2x2, 3x3 and 4x4 arrays as well as a 2.45 GHz narrowband 8x8 MIMO array. The analysis shows an increase of up to 2 b/s/Hz on instant channel capacity with up to 3 pedestrians. There is an increase of up to 1 b/s/Hz in the average capacity of the 4x4 MIMO-OFDM channel when the number of pedestrians goes from 1 to 3. Additionally, an increment of up to 2.5 b/s/Hz in MIMO-OFDM channel capacity was measured for a 4x4 array compared to a 2x2 array in presence of pedestrians. Channel capacity values derived from this analysis are important in terms of understanding the limitations and possibilities for MIMO-OFDM systems in indoor populated environments. MIMO; OFDM; Channel characterization; Channel capacity I.

In this paper, the results and analysis of the measured data for multiple-input multiple-output o... more In this paper, the results and analysis of the measured data for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channels in indoor environment, in presence of pedestrian, are reported. The experiment used 4 sending and 4 receiving antennas and 114 OFDM sub-carriers for each transmission. The mean channel capacity and the dynamic range of the received power increased with the number of pedestrians present within the indoor environment . Each transmitter-to-sender sub-channel had a Signal to Noise Ration (SNR) of 15 db. With three pedestrians, the mean channel capacity rose by up to 2 bps/Hz compared to the vacant room scenario due to the increase in multipath conditions caused by body-shadowing effects. This demonstrates that the use of MIMO in the indoor environment is effective in compensating for the presence of pedestrians.

Considerable advantages for performance will accrue if large flows can be identified and treated ... more Considerable advantages for performance will accrue if large flows can be identified and treated differently in the Internet. DiffServ provides a way to treat flows distinctly in the internet, however configuring DiffServ requires a high level of skill and attention to detail. We seek an approach which is inherently autoconfiguring. In this paper flows are not defined uniquely by information in their packet headers, but instead by their route through the local routing domain. This approach imposes a topological structure on the collection of flow by means of which we can judge how close two flows are together and, where appropriate, judge two or more flows to be part of a single larger flow. The aim is to get closer to the collection of packets generated by a single human request for service. For example, if a user chooses to subdivide a request as a large number of TCP connections, the entire aggregate would still be identified and treated as a single flow. To reduce the complexity of the task of flow management, we identify only flows larger than a certain threshold, without having to deal with the much larger number of small flows. Simulations are used to determine how many large flows need to be found in order to achieve significant improvements in the performance of the Internet as a whole.

The use of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) ... more The use of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) has been considered for the physical layer transmission scheme of the next generation wireless communication systems (e.g. [1]). Accurate analysis and modelling of practical MIMO-OFDM channels are important in designing and optimising this transmission scheme.

Insufficient Quality of Service (QoS) of Voice over Internet Protocol (VoIP) is a growing concern... more Insufficient Quality of Service (QoS) of Voice over Internet Protocol (VoIP) is a growing concern that has lead the need for research and study. In this paper we investigate the performance of VoIP and the impact of resource limitations on the performance of Access Networks. The impact of VoIP performance in Access Networks is particularly important in regions where Internet

2007 Australasian Telecommunication Networks and Applications Conference, 2007

Hajime (2007) Dynamic range analysis on MIMO-OFDM broadband channels in a populated time-varying ... more Hajime (2007) Dynamic range analysis on MIMO-OFDM broadband channels in a populated time-varying indoor environment.

2009 Loughborough Antennas & Propagation Conference, 2009

Channel measurements and simulations have been carried out to observe the effects of pedestrian m... more Channel measurements and simulations have been carried out to observe the effects of pedestrian movement on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channel capacity. An in-house built MIMO-OFDM packet transmission demonstrator equipped with four transmitters and four receivers has been utilized to perform channel measurements at 5.2 GHz. Variations in the channel capacity dynamic range have been analysed for 1 to 10 pedestrians and different antenna arrays (2 × 2, 3 × 3 and 4 × 4). Results show a predicted 5.5 bits/s/Hz and a measured 1.5 bits/s/Hz increment in the capacity dynamic range with the number of pedestrian and the number of antennas in the transmitter and receiver array.

2009 Australasian Telecommunication Networks and Applications Conference (ATNAC), 2009

We investigate Multiple-Input and Multiple-Output Orthogonal Frequency Division Multiplexing (MIM... more We investigate Multiple-Input and Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems behavior in indoor populated environments that have line-of-site (LoS) between transmitter and receiver arrays. The in-house built MIMO-OFDM packet transmission demonstrator, equipped with four transmitters and four receivers, has been utilized to perform channel measurements at 5.2 GHz. Measurements have been performed using 0 to 3 pedestrians with different antenna arrays (2 × 2, 3 × 3 and 4 × 4). The maximum average capacity for the 2x2 deterministic Fixed SNR scenario is 8.5 dB compared to the 4x4 deterministic scenario that has a maximum average capacity of 16.2 dB, thus an increment of 8 dB in average capacity has been measured when the array size increases from 2x2 to 4x4. In addition a regular variation has been observed for Random scenarios compared to the deterministic scenarios. An incremental trend in average channel capacity for both deterministic and random pedestrian movements has been observed with increasing number of pedestrian and antennas. In deterministic scenarios, the variations in average channel capacity are more noticeable than for the random scenarios due to a more prolonged and controlled body-shadowing effect. Moreover due to the frequent Los blocking and fixed transmission power a slight decrement have been observed in the spread between the maximum and minimum capacity with random fixed Tx power scenario.

2009 5th International Conference on Wireless Communications, Networking and Mobile Computing, 2009

Temporal variations caused by pedestrian movement can significantly affect the channel capacity o... more Temporal variations caused by pedestrian movement can significantly affect the channel capacity of indoor MIMO-OFDM wireless systems. This paper compares systematic measurements of MIMO-OFDM channel capacity in presence of pedestrians with predicted MIMO-OFDM channel capacity values using geometric optics-based ray tracing techniques. Capacity results are presented for a single room environment using 5.2 GHz with 2x2, 3x3 and 4x4 arrays as well as a 2.45 GHz narrowband 8x8 MIMO array. The analysis shows an increase of up to 2 b/s/Hz on instant channel capacity with up to 3 pedestrians. There is an increase of up to 1 b/s/Hz in the average capacity of the 4x4 MIMO-OFDM channel when the number of pedestrians goes from 1 to 3. Additionally, an increment of up to 2.5 b/s/Hz in MIMO-OFDM channel capacity was measured for a 4x4 array compared to a 2x2 array in presence of pedestrians. Channel capacity values derived from this analysis are important in terms of understanding the limitations and possibilities for MIMO-OFDM systems in indoor populated environments. MIMO; OFDM; Channel characterization; Channel capacity I.

IEEE Antennas and Wireless Propagation Letters, 2000

The use of topic maps and concept maps has long been encouraged by instructional designers as a m... more The use of topic maps and concept maps has long been encouraged by instructional designers as a means of providing an overview of content in study materials. Educational theory and practice affirm the effectiveness of concept mapping: as a concise summary of a body of knowledge; as a practical means by which students can construct and record their own knowledge; and as a means of evaluating student understanding. This paper presents the aims, methodology and initial findings of a project commenced in Semester 1 2008, to include hyperlinked concept maps as an enhancement to electronic study materials. The project aims to evaluate their effectiveness: in improving student understanding of the concepts in the course; and as a means of navigating and accessing electronic study materials. The course of study is in the field of Microcomputer Design.

Temporal variations caused by pedestrian movement can significantly affect the channel capacity o... more Temporal variations caused by pedestrian movement can significantly affect the channel capacity of indoor MIMO-OFDM wireless systems. This paper compares systematic measurements of MIMO-OFDM channel capacity in presence of pedestrians with predicted MIMO-OFDM channel capacity values using geometric optics-based ray tracing techniques. Capacity results are presented for a single room environment using 5.2 GHz with 2x2, 3x3 and 4x4 arrays as well as a 2.45 GHz narrowband 8x8 MIMO array. The analysis shows an increase of up to 2 b/s/Hz on instant channel capacity with up to 3 pedestrians. There is an increase of up to 1 b/s/Hz in the average capacity of the 4x4 MIMO-OFDM channel when the number of pedestrians goes from 1 to 3. Additionally, an increment of up to 2.5 b/s/Hz in MIMO-OFDM channel capacity was measured for a 4x4 array compared to a 2x2 array in presence of pedestrians. Channel capacity values derived from this analysis are important in terms of understanding the limitations and possibilities for MIMO-OFDM systems in indoor populated environments. MIMO; OFDM; Channel characterization; Channel capacity I.

In this paper, the results and analysis of the measured data for multiple-input multiple-output o... more In this paper, the results and analysis of the measured data for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channels in indoor environment, in presence of pedestrian, are reported. The experiment used 4 sending and 4 receiving antennas and 114 OFDM sub-carriers for each transmission. The mean channel capacity and the dynamic range of the received power increased with the number of pedestrians present within the indoor environment . Each transmitter-to-sender sub-channel had a Signal to Noise Ration (SNR) of 15 db. With three pedestrians, the mean channel capacity rose by up to 2 bps/Hz compared to the vacant room scenario due to the increase in multipath conditions caused by body-shadowing effects. This demonstrates that the use of MIMO in the indoor environment is effective in compensating for the presence of pedestrians.

Considerable advantages for performance will accrue if large flows can be identified and treated ... more Considerable advantages for performance will accrue if large flows can be identified and treated differently in the Internet. DiffServ provides a way to treat flows distinctly in the internet, however configuring DiffServ requires a high level of skill and attention to detail. We seek an approach which is inherently autoconfiguring. In this paper flows are not defined uniquely by information in their packet headers, but instead by their route through the local routing domain. This approach imposes a topological structure on the collection of flow by means of which we can judge how close two flows are together and, where appropriate, judge two or more flows to be part of a single larger flow. The aim is to get closer to the collection of packets generated by a single human request for service. For example, if a user chooses to subdivide a request as a large number of TCP connections, the entire aggregate would still be identified and treated as a single flow. To reduce the complexity of the task of flow management, we identify only flows larger than a certain threshold, without having to deal with the much larger number of small flows. Simulations are used to determine how many large flows need to be found in order to achieve significant improvements in the performance of the Internet as a whole.

The use of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) ... more The use of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) has been considered for the physical layer transmission scheme of the next generation wireless communication systems (e.g. [1]). Accurate analysis and modelling of practical MIMO-OFDM channels are important in designing and optimising this transmission scheme.

Insufficient Quality of Service (QoS) of Voice over Internet Protocol (VoIP) is a growing concern... more Insufficient Quality of Service (QoS) of Voice over Internet Protocol (VoIP) is a growing concern that has lead the need for research and study. In this paper we investigate the performance of VoIP and the impact of resource limitations on the performance of Access Networks. The impact of VoIP performance in Access Networks is particularly important in regions where Internet

2007 Australasian Telecommunication Networks and Applications Conference, 2007

Hajime (2007) Dynamic range analysis on MIMO-OFDM broadband channels in a populated time-varying ... more Hajime (2007) Dynamic range analysis on MIMO-OFDM broadband channels in a populated time-varying indoor environment.

2009 Loughborough Antennas & Propagation Conference, 2009

Channel measurements and simulations have been carried out to observe the effects of pedestrian m... more Channel measurements and simulations have been carried out to observe the effects of pedestrian movement on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channel capacity. An in-house built MIMO-OFDM packet transmission demonstrator equipped with four transmitters and four receivers has been utilized to perform channel measurements at 5.2 GHz. Variations in the channel capacity dynamic range have been analysed for 1 to 10 pedestrians and different antenna arrays (2 × 2, 3 × 3 and 4 × 4). Results show a predicted 5.5 bits/s/Hz and a measured 1.5 bits/s/Hz increment in the capacity dynamic range with the number of pedestrian and the number of antennas in the transmitter and receiver array.

2009 Australasian Telecommunication Networks and Applications Conference (ATNAC), 2009

We investigate Multiple-Input and Multiple-Output Orthogonal Frequency Division Multiplexing (MIM... more We investigate Multiple-Input and Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems behavior in indoor populated environments that have line-of-site (LoS) between transmitter and receiver arrays. The in-house built MIMO-OFDM packet transmission demonstrator, equipped with four transmitters and four receivers, has been utilized to perform channel measurements at 5.2 GHz. Measurements have been performed using 0 to 3 pedestrians with different antenna arrays (2 × 2, 3 × 3 and 4 × 4). The maximum average capacity for the 2x2 deterministic Fixed SNR scenario is 8.5 dB compared to the 4x4 deterministic scenario that has a maximum average capacity of 16.2 dB, thus an increment of 8 dB in average capacity has been measured when the array size increases from 2x2 to 4x4. In addition a regular variation has been observed for Random scenarios compared to the deterministic scenarios. An incremental trend in average channel capacity for both deterministic and random pedestrian movements has been observed with increasing number of pedestrian and antennas. In deterministic scenarios, the variations in average channel capacity are more noticeable than for the random scenarios due to a more prolonged and controlled body-shadowing effect. Moreover due to the frequent Los blocking and fixed transmission power a slight decrement have been observed in the spread between the maximum and minimum capacity with random fixed Tx power scenario.

2009 5th International Conference on Wireless Communications, Networking and Mobile Computing, 2009

Temporal variations caused by pedestrian movement can significantly affect the channel capacity o... more Temporal variations caused by pedestrian movement can significantly affect the channel capacity of indoor MIMO-OFDM wireless systems. This paper compares systematic measurements of MIMO-OFDM channel capacity in presence of pedestrians with predicted MIMO-OFDM channel capacity values using geometric optics-based ray tracing techniques. Capacity results are presented for a single room environment using 5.2 GHz with 2x2, 3x3 and 4x4 arrays as well as a 2.45 GHz narrowband 8x8 MIMO array. The analysis shows an increase of up to 2 b/s/Hz on instant channel capacity with up to 3 pedestrians. There is an increase of up to 1 b/s/Hz in the average capacity of the 4x4 MIMO-OFDM channel when the number of pedestrians goes from 1 to 3. Additionally, an increment of up to 2.5 b/s/Hz in MIMO-OFDM channel capacity was measured for a 4x4 array compared to a 2x2 array in presence of pedestrians. Channel capacity values derived from this analysis are important in terms of understanding the limitations and possibilities for MIMO-OFDM systems in indoor populated environments. MIMO; OFDM; Channel characterization; Channel capacity I.

IEEE Antennas and Wireless Propagation Letters, 2000

The use of topic maps and concept maps has long been encouraged by instructional designers as a m... more The use of topic maps and concept maps has long been encouraged by instructional designers as a means of providing an overview of content in study materials. Educational theory and practice affirm the effectiveness of concept mapping: as a concise summary of a body of knowledge; as a practical means by which students can construct and record their own knowledge; and as a means of evaluating student understanding. This paper presents the aims, methodology and initial findings of a project commenced in Semester 1 2008, to include hyperlinked concept maps as an enhancement to electronic study materials. The project aims to evaluate their effectiveness: in improving student understanding of the concepts in the course; and as a means of navigating and accessing electronic study materials. The course of study is in the field of Microcomputer Design.