Enhanced Uplink Research Articles

UMTS EUL throughput improvements using boost power in 1Tx‐2Rx DSDA

In the Tx timesharing for universal mobile telecommunications system (UMTS) and global system for mobile communications 1Tx-2Rx dual-SIM dual-active (DSDA) scenario, UMTS UMTS enhanced uplink (EUL) had performance degradation due to discontinuous transmission. Therefore, the code rate-based mitigation scheme was evaluated to reduce the performance degradation. Even though this scheme had significant gain, high complexity implementation was required. Thus, the boost power-based mitigation scheme is proposed and analysed from the throughput improvement and implementation complexity point of view.

Enhanced Uplink Scheduling for Continuous Connectivity in High Speed Packet Access Systems

The efficiency of high speed packet access (HSPA) systems is mainly based on channel quality information (CQI) reports transmitted by user equipment (UE) to Node B. In this paper, we propose an improved CQI prediction scheme based on a finite state Markov chain (FSMC) model for wireless channel, in order to reduce CQI signaling overhead in the HSPA system. Then, we introduce an enhanced uplink packet scheduling (EUPS) scheme to provide quality of services (QoS) guaranteed for continuous packet connectivity in the enhanced uplink (EUL). EUPS serves the active UEs not only according to buffer status but also according to reported state of the wireless channel of each UE. The performance of the proposed scheme in terms of average packet delay, average packet drop and average cell throughput is compared to the classical scheduler of 3GPP standards. The simulation results show the effectiveness of the proposed scheme.

Recursive Noise Floor Estimation in WCDMA

Online estimation of the noise floor is essential for the accurate scheduling of wideband code-division multiple-access (WCDMA) enhanced uplink (EUL) channel transmissions. The noise floor is used for computation of the load of the uplink of the cell, which is then used to compute the momentary headroom available for EUL traffic. This paper proves a result on Kalman filter scaling, which significantly extends the dynamic range of a previous noise-floor-estimation scheme. This paper proceeds by proving that an optimal Bayesian minimum estimator can be written in recursive form using geometric-rather than arithmetic-averaging. As compared with previous algorithms, the recursive scheme reduces the memory requirement without compromising performance, at the same time that the tracking properties are enhanced.

Soft Uplink Load Estimation in WCDMA

Wideband code-division multiple-access (WCDMA) enhanced uplink (EUL) channel transmissions are typically scheduled to time intervals where the interference and load conditions of a cell are favorable-hence, load estimation is central for EUL performance. This paper first proves that the uplink load, which is expressed as the rise over thermal (RoT), is unobservable with any linear estimation technique using measurements in a single radio base station (RBS) of (1) received total wideband power (RTWP) and (2) cell channel powers. A soft nonlinear Bayesian load estimator is proposed to circumvent these problems. The three-stage algorithm first estimates the RTWP, as well as residual power consisting of the sum of the thermal noise floor power and the neighbor cell interference. A time-variable Kalman estimator is used for this first step. The thermal noise power is then approximated by the Bayesian conditional probability density function (pdf) of the minimum of the estimated residual power. The 1-D conditional pdf of the RoT then follows from the quotient of two pdf's-the estimated pdf of the RTWP and the estimated conditional pdf of the thermal noise power. After discretization, the optimal RoT is calculated as a conditional mean.