Poonam Singh - Academia.edu (original) (raw)

Papers by Poonam Singh

International Conference on Communication and Electronics System Design, 2013

In this paper, we present a quantitative comparison of two agile modulation techniques employed b... more In this paper, we present a quantitative comparison of two agile modulation techniques employed by cognitive radio transceivers operating in a dynamic spectrum access (DSA) network. One of the modulation techniques is single carrier frequency division multiple access (SC-FDMA). The other modulation technique under study is a variant of multicarrier code division multiple access (MC-CDMA). Although several studies comparing conventional OFDM and MC-CDMA has been conducted in literature to justify robust error performance of MC-CDMA, a quantitative performance evaluation of these schemes has not been performed when employed in a DSA network. In this paper we show that their performances can be significantly different from the conventional setup. Analytical expressions for the error probability of an SC-FDMA transceiver have been derived and compared with computer simulation results. The results show that the error robustness of SC-FDMA is relatively better then MC-CDMA in underlay communication.

2012 5th International Conference on Computers and Devices for Communication (CODEC), 2012

Channel overloading in Code Division Multiple Access (CDMA) facilitates to accommodate more numbe... more Channel overloading in Code Division Multiple Access (CDMA) facilitates to accommodate more number of users than the assigned spreading factor N. Our proposal for a synchronous CDMA technique for the uplink of a cellular system over additive white gaussian noise (AWGN) channel achieves oversaturation by using the same set of orthogonal Walsh Hadamard codes and a receiver with lower complexity. The technique involves dividing the total number of active users into G groups, each with L users. Each user in a group is assigned the same signature sequence but with different chip duration. Users in a group can be classified as Primary and Secondary. The Primary user avails the spreading sequence with the maximum chip duration Tc. The rest L-1 (secondary) users are assigned the same code with chip duration as multiples of Tc/L. Unlike conventional Direct Sequence CDMA (DS-CDMA), all the users participate in spreading using the proposed Unequal Chip Delay Spreading (UCDS) technique.The receiver contains a switching unit to separate the received stream into L sub-streams followed by the detection process using a simple multi user detector. On the other hand, L levels of Unequal Error Protection (UEP) can be attained due to the unequal amount of multiple access interference (MAI) existing in alternate chip interval during transmission. Unequal chip delay spreading finally enables it to have a L-fold increase in the user data rate at the receiving end as compared to that of the transmission.

2013 IEEE International Conference on Electronics, Computing and Communication Technologies, 2013

Channel overloading in Code Division Multiple Access (CDMA) paves the way to achieve more no of u... more Channel overloading in Code Division Multiple Access (CDMA) paves the way to achieve more no of users (>N) in a space with dimension equal to the spreading factor (N).It puts its own priority over the conventional CDMA to provide broadband access in cellular wireless communication. A new overloading scheme for the uplink of cellular CDMA has been proposed in [7] using unequal chip delay spreading (UCDS). It divides all the active users into G groups with each group containing L number of users. Each user in a group is assigned the same orthogonal code, but with different chip durations (multiple of Tc/L). For spreading, all the L Users in a group use the assigned unique code with the insertion of predefined time delay. During spreading each user in a group has to go through unequal time delay between each successive spreading chip. Addition of suitable delays helps in maintaining the correct time alignment among all the users in a group. The receiver uses a very simple orthogonal successive interference cancellation (OSIC) multi user detector in order to recover the message bits of all the users. In this paper, the performance of this new overloading scheme (UCDS-CDMA) with an overloading factor (OF) of TWO has been evaluated with different levels of error in power control. The system model has been designed mainly for the uplink of the cellular CDMA over an additive white Gaussian noise (AWGN) channel. The effect of erroneous power control in the uplink of UCDS-CDMA costs a SNR of 1.1 dB, 1.3 dB and 1.6 dB as compared to the conventional perfectly power controlled underloaded CDMA (OF=1) with the power control error of 1 dB, 1.5 dB and 2 dB respectively at a BER of 10-3 .

Journal of vector borne diseases, 2012

The article reviews the issue of climate change and health in the Indian context. The importance ... more The article reviews the issue of climate change and health in the Indian context. The importance of climate change leading to estimated loss of above 2.5 million DALYs in southeast Asia, mortality due to heat waves, and the importance of air quality related respiratory diseases, disasters due to excessive floods, malnutrition due to reduction in rice, maize and sorghum crops etc. Latest work undertaken in India, vis-a-vis current scenario and need for further work has been discussed. There is felt need of further studies on assessing the impact on dengue and chikungunya as the transmission dynamics of these diseases involve water availability, storage and life style, etc. Uncertainties and knowledge gaps identified in the studies undertaken so far have also been highlighted. As regards to vector borne diseases, there is a need to concentrate in the areas which are presently free from malaria and with use of best available tools of interventions in already disease endemic areas like ...

International Conference on Communication and Electronics System Design, 2013

In this paper, we present a quantitative comparison of two agile modulation techniques employed b... more In this paper, we present a quantitative comparison of two agile modulation techniques employed by cognitive radio transceivers operating in a dynamic spectrum access (DSA) network. One of the modulation techniques is single carrier frequency division multiple access (SC-FDMA). The other modulation technique under study is a variant of multicarrier code division multiple access (MC-CDMA). Although several studies comparing conventional OFDM and MC-CDMA has been conducted in literature to justify robust error performance of MC-CDMA, a quantitative performance evaluation of these schemes has not been performed when employed in a DSA network. In this paper we show that their performances can be significantly different from the conventional setup. Analytical expressions for the error probability of an SC-FDMA transceiver have been derived and compared with computer simulation results. The results show that the error robustness of SC-FDMA is relatively better then MC-CDMA in underlay communication.

2012 5th International Conference on Computers and Devices for Communication (CODEC), 2012

Channel overloading in Code Division Multiple Access (CDMA) facilitates to accommodate more numbe... more Channel overloading in Code Division Multiple Access (CDMA) facilitates to accommodate more number of users than the assigned spreading factor N. Our proposal for a synchronous CDMA technique for the uplink of a cellular system over additive white gaussian noise (AWGN) channel achieves oversaturation by using the same set of orthogonal Walsh Hadamard codes and a receiver with lower complexity. The technique involves dividing the total number of active users into G groups, each with L users. Each user in a group is assigned the same signature sequence but with different chip duration. Users in a group can be classified as Primary and Secondary. The Primary user avails the spreading sequence with the maximum chip duration Tc. The rest L-1 (secondary) users are assigned the same code with chip duration as multiples of Tc/L. Unlike conventional Direct Sequence CDMA (DS-CDMA), all the users participate in spreading using the proposed Unequal Chip Delay Spreading (UCDS) technique.The receiver contains a switching unit to separate the received stream into L sub-streams followed by the detection process using a simple multi user detector. On the other hand, L levels of Unequal Error Protection (UEP) can be attained due to the unequal amount of multiple access interference (MAI) existing in alternate chip interval during transmission. Unequal chip delay spreading finally enables it to have a L-fold increase in the user data rate at the receiving end as compared to that of the transmission.

2013 IEEE International Conference on Electronics, Computing and Communication Technologies, 2013

Channel overloading in Code Division Multiple Access (CDMA) paves the way to achieve more no of u... more Channel overloading in Code Division Multiple Access (CDMA) paves the way to achieve more no of users (>N) in a space with dimension equal to the spreading factor (N).It puts its own priority over the conventional CDMA to provide broadband access in cellular wireless communication. A new overloading scheme for the uplink of cellular CDMA has been proposed in [7] using unequal chip delay spreading (UCDS). It divides all the active users into G groups with each group containing L number of users. Each user in a group is assigned the same orthogonal code, but with different chip durations (multiple of Tc/L). For spreading, all the L Users in a group use the assigned unique code with the insertion of predefined time delay. During spreading each user in a group has to go through unequal time delay between each successive spreading chip. Addition of suitable delays helps in maintaining the correct time alignment among all the users in a group. The receiver uses a very simple orthogonal successive interference cancellation (OSIC) multi user detector in order to recover the message bits of all the users. In this paper, the performance of this new overloading scheme (UCDS-CDMA) with an overloading factor (OF) of TWO has been evaluated with different levels of error in power control. The system model has been designed mainly for the uplink of the cellular CDMA over an additive white Gaussian noise (AWGN) channel. The effect of erroneous power control in the uplink of UCDS-CDMA costs a SNR of 1.1 dB, 1.3 dB and 1.6 dB as compared to the conventional perfectly power controlled underloaded CDMA (OF=1) with the power control error of 1 dB, 1.5 dB and 2 dB respectively at a BER of 10-3 .

Journal of vector borne diseases, 2012

The article reviews the issue of climate change and health in the Indian context. The importance ... more The article reviews the issue of climate change and health in the Indian context. The importance of climate change leading to estimated loss of above 2.5 million DALYs in southeast Asia, mortality due to heat waves, and the importance of air quality related respiratory diseases, disasters due to excessive floods, malnutrition due to reduction in rice, maize and sorghum crops etc. Latest work undertaken in India, vis-a-vis current scenario and need for further work has been discussed. There is felt need of further studies on assessing the impact on dengue and chikungunya as the transmission dynamics of these diseases involve water availability, storage and life style, etc. Uncertainties and knowledge gaps identified in the studies undertaken so far have also been highlighted. As regards to vector borne diseases, there is a need to concentrate in the areas which are presently free from malaria and with use of best available tools of interventions in already disease endemic areas like ...