Sanjiv Nanda
Rutgers University
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Featured researches published by Sanjiv Nanda.
vehicular technology conference | 1991
Sanjiv Nanda; David J. Goodman; Uzi Timor
Equilibrium point analysis is used to evaluate system behavior in a packet reservation multiple access (PRMA) protocol based network. The authors derive the probability of packet dropping given the number of simultaneous conversations. The authors establish conditions for system stability and efficiency. Numerical calculations based on the theory show close agreement with computer simulations. They also provide valuable guides to system design. Because PRMA is a statistical multiplexer, the channel becomes congested when too many terminals are active. For a particular example it is shown that speech activity detection permits 37 speech terminals to share a PRMA channel with 20 slots per frame, with a packet dropping probability of less than 1%. >
IEEE Journal on Selected Areas in Communications | 1999
Krishna Balachandran; Srinivas R. Kadaba; Sanjiv Nanda
We propose a technique to measure channel quality in terms of signal-to-interference plus noise ratio (SINR) for the transmission of signals over fading channels. The Euclidean distance (ED) metric, associated with the decoded information sequence or a suitable modification thereof, is used as a channel quality measure. Simulations show that the filtered or averaged metric is a reliable channel quality measure which remains consistent across different coded modulation schemes and at different mobile speeds. The average scaled ED metric can be mapped to the SINR per symbol. We propose the use of this SINR estimate for data rate adaptation, in addition to mobile assisted handoff (MAHO) and power control. We particularly focus on data rate adaptation and propose a set of coded modulation schemes which utilize the SINR estimate to adapt between modulations, thus improving the data throughput. Simulation results show that the proposed metric works well across the entire range of Dopplers to provide near-optimal rate adaptation to average SINR. This method of adaptation averages out short-term variations due to Rayleigh fading and adapts to the long-term effects such as shadowing. At low Dopplers, the metric can track Rayleigh fading and match the rate to a short-term average of the SINR, thus further increasing throughput.
global communications conference | 1990
Sanjiv Nanda
It is shown that PRMA (packet-reservation multiple-access) gracefully accepts low-rate data terminals with moderate data packet delays. Due to the two classes of terminals, calculation of system equilibrium requires the solution of two simultaneous nonlinear equations. By a judicious change of variables, this is reduced to a univariate problem of the same form as the speech-only system. Results for a particular design example show that, with a small reduction in the number of speech terminals, all terminals can be provided with a low-rate data capability (1200/2400 b/s) with data packet delays of a few hundred milliseconds. The results are of interest in connection with the development of future microcellular systems which will require distributed network control.<<ETX>>
IEEE Transactions on Wireless Communications | 2005
Wei Luo; Krishna Balachandran; Sanjiv Nanda; Kirk K. Chang
Radio link control (RLC) protocols are typically employed for reliable in-sequence delivery of service data units (SDUs) in wireless packet data systems. The RLC layer segments packets obtained from the upper layer (referred to as SDUs) into smaller RLC transmission units (or blocks) and uses selective-repeat automatic repeat request (SR-ARQ) for error recovery of RLC blocks. In earlier work, SR-ARQ performance is typically characterized in terms of the long-term throughput or in-sequence delivery delay of RLC blocks. The SDU delivery delay which is a more meaningful measure of RLC performance (in terms of the service provided to a higher layer, e.g., transmission control protocol) has not been quantified. In this paper, we analyze the SDU delivery delay of SR-ARQ as a function of the SDU size and the channel coding scheme employed. Closed-form delay expressions as well as approximations are provided. The analysis is verified through enhanced general packet radio service RLC simulations. Based on the analysis, we propose that link adaptation be backlog dependent in order to reduce the SDU delivery delay at the RLC layer.
global communications conference | 1996
Chih-Lin I; Sanjiv Nanda
To provide a smooth migration path to serve bursty packet data traffic at rates up to four to eight times the basic single (voice) channel rate in wireless CDMA (standard) networks, a unified bandwidth on demand platform is realized by multi-code CDMA which allows users to transmit on demand using multiple codes. We propose a network control strategy that accounts for channel loading, interference, and soft handoff in making the rate assignment and QOS decisions. Our algorithms, called load and interference based demand assignment (LIDA), enable the dynamic, packet-like demand-assigned access of MC-CDMA with load and interference based control in a cellular environment. It protects voice (and other high priority or delay sensitive) isochronous users, but accommodates peak rate access by high data rate users when the load on the channel permits. Thus the sharing of the channel between voice users and high data rate services is possible without the potentially very high voice outage probability.
IEEE Personal Communications | 1999
Krishna Balachandran; Richard Paul Ejzak; Sanjiv Nanda; Stanislav Vitebskiy; Shiv Mohan Seth
This article provides an overview of the flexible, high-performance packet data channel that has been designed for high-rate packet data services over IS-136 TDMA channels. To achieve the highest data rates in the limited 30 kHz channel bandwidth, the packet data channel is designed for adaptive modulation and, in addition to a fixed coding mode, permits operation using an incremental redundancy mode.
vehicular technology conference | 1990
Louay M. A. Jalloul; Sanjiv Nanda; David J. Goodman
Packet reservation multiple access (PRMA) allows a group of spatially dispersed terminals to transmit packet voice and data over a common channel. A means to model and evaluate the effects of packet transmission errors on PRMA is developed. PRMA is considered in the context of a cellular system, and the effects of fading on the performance of PRMA are studied. PRMA performance is assessed in terms of system capacity, outage, and cellular efficiency when the transmission channel is subject to slow and fast fading. It is shown that for fast-fading channels simple forward-error correction is sufficient for acceptable system performance. In slow-fading channels, however, other techniques such as selection diversity are required.<<ETX>>
vehicular technology conference | 2000
Farooq Ullah Khan; Sarath Kumar; Kamesh Medepalli; Sanjiv Nanda
We provide link layer new data and retransmission buffer size distributions for HTTP and FTP applications in an IS-2000 system. The results are given for different TCP window size, TCP segment size, air link FER and data rates. For HTTP application, the number of parallel TCP connections is limited to either 1 or 4. We found that smaller (larger) new data buffers (retransmission buffers) are required at higher data rates. Moreover, for error free transmission over the air link, a large fraction of data (from TCP window) stays in the new data buffers while for the case of link errors, the retransmission buffer size is also large. The maximum retransmission buffer size is a function of the air link RTT (i.e. number of rounds of RLP NAKs) and is independent of the link error rate.
global communications conference | 2000
Wei Luo; Krishna Balachandran; Sanjiv Nanda; Kirk K. Chang
In wireless packet data systems such as the Enhanced General Packet Radio Service (EGPRS), selective ARQ is used for error recovery over a radio link. In earlier work, the radio link control (RLC) performance is typically characterized in terms of the throughput and the size of the higher layer protocol data units (PDUs) or the packets to be transferred is ignored. We propose that the link adaptation be based on user perceived delay instead of the throughput.
wireless communications and networking conference | 2000
Krishna Balachandran; Cristian Demetrescu; Richard Paul Ejzak; Sanjiv Nanda; Hong Xie
The General Packet Radio Service (GPRS) was introduced by ETSI to meet the ever-increasing demand for wireless data over the GSM radio interface. Enhanced GPRS (EGPRS Phase 1) was later introduced in order to increase the spectrum efficiency and data throughput by using 8-PSK modulation and link adaptation techniques. While (E)GPRS uses packet-switched technology to efficiently transmit best-effort data, real-time services (e.g. voice) are currently supported only via circuit-switched systems. This service separation reduces the potential spectrum efficiency gain resulting from multiplexing different services on the same radio channel. This paper describes the key new concepts needed to support statistical multiplexing of different radio access bearer classes over the GSM/EDGE radio access network (GERAN) air interface. The focus is on the definition of new traffic and control channels to support statistical multiplexing of speech, real-time data, and non-real-time data, and the corresponding new MAC procedures that are needed to guarantee quality of service (QoS).