Vehicular Technology Conference, 1988, IEEE 38th

Publications
A 900 MHz CMOS BFSK transceiver is used as a test vehicle to evaluate the impact of copper interconnect on CMOS RF circuit performance. The RF front-end contains spiral inductors and fractal capacitors, whose parasitics degrade the receiver sensitivity. It is shown that spiral inductor quality factors (Qs) are on average 70 % higher when copper interconnect is used in place of aluminum, while capacitor Qs are also improved significantly. As a result, the front-end receiver gain is increased by nearly 4 dB and the receiver noise figure is reduced by more than 1 dB when copper is used instead of aluminum. The 20 mW transceiver fabricated in the 0.18 μm copper UMC process can achieve a 0.1 % BER for a -98 dBm input, while operating at 200 kb/s data. The maximum power output of transmit section is +10 dBm
 
A data-aided synchronization method for jointly estimating the symbol timing and carrier frequency offset has been proposed for 4-ary CPFSK (continuous phase frequency shift keying) modulation with h = 0.25. The proposed algorithm is based on a special preamble and has a feedforward structure that is suitable for digital realizations. Simulation results indicate the timing and frequency recovery algorithm can be employed with a short preamble of 16 symbols and is well suited for burst mode transmissions.
 
A differentially coherent receiver which uses the Viterbi algorithm is presented. This receiver compensates for intersymbol interference (ISI) and avoids noise enhancement. A phase estimate which takes into account the presence of inherent ISI in the signal is derived. This phase estimate is then used in the decision metric of a coherent receiver. The resulting decision rule can be implemented using the Viterbi algorithm. The complexity of the resulting receiver increases with the duration of observation used by the implicit phases estimator. A simple four-state Viterbi receiver with good performance is obtained when the phase estimate is based on one observable. Simulation results are given
 
For BPRCPM (binary partial-response continuous-phase modulation) with modulation index equal to 0.5, it is possible to construct a simple and near-optimum minimum-shift keying (MSK)-type coherent receiver. The S-curve of a decision-feedback phase-locked loop (PLL) is derived to provide a carrier reference for any BPRCPM of modulation index 0.5. The results obtained are illustrated by applying them to the Gaussian minimum-shift keying signal (GMSK) of parameter BT =0.5
 
The author presents a method for the design of an MMSE (minimum mean-squared error) optimum receiver filter for the differentially coherent detection of CPM (continuous phase modulation) with modulation index 0.5. The receiver filter is equivalent to the cascade of a matched filter and an equalizer, to reduce inherent intersymbol interference (ISI). The performance can be improved when the delay between signals, multiplied by the differential detector, is increased from one to M bit time intervals. This decreases the effect of noise correlation, and consequently decreases the bit error probability. It is shown that performance degradation with respect to that of the differential binary phase-shift keying system is due to inherent ISI contained in the signal and also due to noise enhancement and correlation caused by the receiver filter. The bit error probability on the Gaussian channel is calculated by assuming that ISI is Gaussian. The Gaussian minimum-shift keying signal is used for illustration
 
The development and operation of a dual-band time-domain radar system used to measure indoor multipath propagation characteristics in several office buildings and factories are described. The system operates at 1.3 GHz and 4.0 GHz and uses 4-ns RMS pulses to provide estimates of indoor radio channel impulse responses. The effects of antenna diversity, frequency scaling, and topography on indoor radio system design are quantified through analyses of measured propagation data. The data are used to develop and refine wideband channel models for multipath propagation in factories and open-plan office buildings and provide insight into the validity of geometric modeling techniques for predicting channel characteristics
 
The tremendous growth of mobile radio systems and the future requirements for PCS will create a need for additional communication networks, particularly in densely populated urban areas where future generations of mobile systems will be introduced. System designers and radio frequency spectrum planners will require a detailed knowledge of indoor channel characteristics such as path loss, channel fading and pulse delays etc. The computation of path loss is of great importance to the planning of wireless indoor communication systems. Propagation measurements were performed at 450 MHz, 900 MHz, 1.35 GHz and 1.89 GHz in the corridors on the second, first and ground floors of an Institute's building. A computer simulation tool was adopted for the calculation of channel parameters. Values of path loss exponent `n', standard deviation, RMS delay spread, a measure for the spreading of the received signal and Rice factor `k' were evaluated using experimental and simulated data. The Rice factor was found to vary between 0.2 to 9.60
 
The propagation characteristics, data transmission quality, and service area of a quasi-microwave railway communication system are described. Measurements of propagation path loss taken along a typical railway route and in tunnels are presented
 
The 1.5 GHz pocket-size portable telephone has been developed by NTT DoCoMo for our personal digital cellular system. The telephone's major design parameters, the configuration of the radio unit, software configuration, and interfaces to fax/modem adaptors are described. Besides being compact, the portable telephone features high speech quality, long stand-by time, high quality data communication and a user-friendly man-machine interface
 
The authors present results from tests on an LSR-FEC (lower-shift RELP with forward error correction) coder for 8-kb/s channels and consider issues related to the operation of the coder in mobile telephone systems. The simple error protection scheme combined with smoothing techniques on the residual signal reconstruction contribute to robustness of the coder at error rates up to 1%. An implementation of the LSR-FEC coder in real time on commercially available hardware is described. The coder showed performance equivalent to 16 kb/s CVSD (continuous variable slope delta modulation) on the mean opinion scores scale under noisy conditions. The results of these experiments indicate that the coder, with digitized speech transmission at 1.5 GHz, is an attractive candidate for use in a mobile radio system
 
Urban measurements were carried out in the Tokyo metropolitan area and rural measurements in the Hiraiso region. Radio propagation loss was measured at 2 cm intervals along the measuring routes, and median propagation losses in the three frequency bands was compared. In the urban experiment, the influence of obstacles on median values of radio propagation loss is almost the same in the three frequency bands except for the constant propagation loss factor, which is different for each frequency. The average difference in the median value of propagation loss between the 1.5 GHz band and the 2.3 GHz band is about 5 dB, while that between the 1.5 GHz band and the 2.6 GHz band is about 8 dB
 
Differential coding CDMA (diffCDMA) is verified to conquer the fatal transmission error when communications are carried from high speed vehicles running through an urban environment with rapid multi-ray Rayleigh channels. With the introduction of differential coding into the primary modulation and employing analytic receiving for primary differential demodulation, the proposed diffCDMA system improves the transmission characteristics of similar CDMA systems such as IS-95 and WcdmaOne IMT2000 for mobile communications at vehicle speeds of more than 100 mile/h mobiles even if a multi-ray environment. Previously, differential coding primary modulation has not been considered for use with CDMA owing to the strict sense synchronization required in demodulation, which suffered from bit error under such rapid multi-ray Rayleigh fading. However, its use is now possible in high speed and high capacity transmission since analytic receiving is being adopted into CDMA systems. In the demodulation procedure of the diffCDMA, the received waves are first detected after multi-ray propagation with certain inevitable errors both in phase and frequency of the recovered carrier for the pseudo synchronization primary demodulation during analytic receiving
 
Given the current interest being shown in the utilization of the frequency band around 1.7/1.8 GHz and 60 GHz, work has been undertaken to determine channel characteristics in these two ranges. The authors describe wideband measurements which have been conducted in a variety of indoor locations. RMS (root mean square) delay spreads were calculated and used to compare levels of multipath activity at the two frequencies. The levels of multipath measured at the two frequencies can be related to the size of the rooms involved and the measurement techniques. Any differences due to atmospheric absorption at 60 GHz were found to be negligible
 
The practical diversity performances achievable inside a building at 1.75 GHz are compared for three techniques: two-branch space diversity, two-branch frequency diversity, and four-branch hybrid diversity. Results are based on data collected using a four-branch dual-frequency envelope receiver with two antennas and with a dual-frequency transmitter located in various rooms on one floor of a university building. Envelope cross-correlations are calculated and diversity gain using selection combining is measured for various frequency diversity spacings and antenna separations. The distributions of correlations and diversity gain at different locations are presented
 
A study of parameters used in developing ray optical prediction methods for indoor radio propagation at 1.8 GHz has been initiated. Measurements have been made of reflection coefficients and transmission losses and these have been applied to a simple multi-ray model of propagation down a corridor. Predictions compared with measured results of propagation loss on a floor of a modern multi-storey building containing offices and laboratories demonstrate the need to include diffraction effects in the analysis
 
This paper describes the results of an experimental investigation into wideband channel characterisation at 1.8 GHz. The experiments were undertaken in the City of Liverpool using a swept time-delay cross-correlation (STDCC) channel sounder. This was used to measure the complex impulse response of the channel. The inclusion of an automatic gain control in the RF stage allowed continuous measurements for up to 200 m. The results show smaller values for the time domain descriptors and only fades of about 1.5 dB in the frequency domain
 
A channel measurement campaign, done with a system from the University of Kassel, is reported. With very high bandwidth (600 MHz), a large room has been measured at 1.8 GHz with a moving antenna, forming a synthetic aperture. The transformation from the transfer function in the frequency-domain to the time-domain received signal, with the training sequence included, is explained. On these data, the space alternating generalised expectation maximisation (SAGE) algorithm is applied to extract with high resolution the direction of arrival (DOA) parameters, in this case the time delay, the azimuth angle and the complex amplitude for every significant path. The extraction results are evaluated and visually interpreted.
 
In this paper, the time and angular dispersion nature of indoor channels is evaluated by a spatio-temporal channel sounder. In the first experiment, a sports hall, as typical large indoor area, was selected. The results obtained by using two different measurement techniques and those obtained by a ray tracing software are compared. A good overall agreement between the measured and modeled spatio-temporal impulse responses is obtained. In the second experiment, the angular distribution of a typical small indoor area is analyzed
 
In this outdoor propagation study low antenna heights of 1.7 m are used at both the transmitter and the receiver to measure wideband (100 MHz baseband) power-delay profiles (PDPs) of the channel for a peer-to-peer communications system operating at 1.8 GHz. Rural and urban areas are studied in 22 different transmitter-receiver links, and the path loss and delay spread characteristics are presented. The small-scale multipath fading characteristics are measured in detail by recording 160 PDPs within each local area. This paper shows the measurement setup for calculation of the fading rate variance and the estimation of the angular spread of each multipath component. The accuracy of the angular spread is discussed
 
It has been demonstrated that when the mobile terminal (MT) is stationary or moving at a very low speed, the uplink spatial signature of the MT is stable enough and can be used as a downlink weight vector in time-division-duplex (TDD) smart antenna systems. However, when the terminal is moving at a relatively high speed, the Doppler effect can cause the spatial signature to change quickly. In order to understand the effects of fast moving MT on spatial signatures, experiments are conducted using a 1.8 GHz real-time smart antenna testbed with a uniform circular array. When the MT moves within 50 milliseconds, those parameters such as spatial signatures and direction-of-arrivals (DOAs) are presented, and variation of uplink spatial signatures relative to downlink spatial signatures are analyzed
 
Installing a personal communications system may not be a straightforward task, since indoor coverage predictions seem to be critical and time dispersion problems may occur. Therefore, a channel sounder has been designed to assess radio channels in the 1.8-GHz band in real time. Parameters characterizing the channel for a particular system are proposed, and their relevance has been investigated and verified for a particular case. Measurements carried out in a warehouse show the importance of careful planning of the fixed stations for an indoor system
 
A statistical analysis of amplitudes corresponding to multipath components in outdoor (urban/suburban) channels is presented. The study is based on short-term complex impulse response measurements conducted in Stockholm at 1.88 GHz carrier frequency with 5 MHz bandwidth. The actual investigations show that the Rice distribution gives the best fitting in the Kramer-von-Mises sense. Further it is shown that in average the strongest tap fades less than the other taps in the impulse response. A global average model was devised for the power delay profile and corresponding Rice K-factor
 
This paper reports the measurement and analysis of a wideband radio channel at 1.89 GHz within a suburban propagation environment. Mean delay spread was found to be 2.000 μs and 1.928 μs for LoS and NLoS conditions respectively. The coherence bandwidth that characterizes the area varies from 123 kHz in NLoS cases to 103 kHz in LoS cases, providing significant data rates. Measured delay spread was found to be highly variable with increasing separation between transmitter and receiver. Finally, coherence bandwidth is found to be inversely proportional to the RMS delay spread and modeled in a minimum mean square error sense.
 
This paper addresses the benefits achievable with advanced base station antennas for 1.9 GHz personal communications services (PCS). High-gain antennas, multiple sub-aperture diversity combining, and adaptive array processing are all parts of the advanced antenna concept. A measurement program was carried out in urban and suburban environments to preview the performance achievable with large antennas. Results indicate that very tall narrow antenna subarrays can produce the desired high gain while minimizing the amount of beam-steering and beamforming required
 
New RF circuit techniques have overcome the distortion problems for low supply voltages. The RF IC chip-set for the 1.9 GHz Japanese personal handy phone (PHP) system includes a low noise amplifier (GaAs MMIC), a mixer (GaAs MMIC), a linear power amplifier (GaAs MMIC), a T/R switch (GaAs MMIC), a 1.9 GHz direct-conversion quadrature modulator (Si LSI), and a frequency synthesizer (Si LSI). These components achieve very low power consumption at very low supply voltages such as 2.0 to 2.4 V
 
Frequency domain channel propagation measurements in the 800-1000 MHz band have been performed with ground-lying antennas. The range of path-loss exponent and shadowing variance for indoor and outdoor environment were determined. The range of these values roughly agree with those measured for higher elevation antennas. The frequency selectivity of the RF channel was also characterized by means of determining the average coherence bandwidth (CBW). It was observed that there is a relationship between CBW and distance between transmitting and receiving antennas
 
Leaky cable tunnel radio systems for the 75 MHz to 450 MHz frequency bands have been successfully used in Switzerland for 10 years. Road tunnels up to 16 km long have been equipped with VHF leaky cable systems using up to 24 cascaded wideband amplifiers. More recent systems use dual-band amplifiers (75/150 and 450 MHz). Condensation can be a problem; therefore the effect of moisture on the cable attenuation has to be carefully assessed. Disaster-proof systems with two cables running in opposite directions can provide radio coverage even when both cables are interrupted. At 900 MHz, antennas instead of leaky cables have proven to be a more economical solution. However, the effect of the traffic density, especially the filling factor, has to be kept carefully under control. For rectangular road tunnels, a spacing of about 4 km between base stations is possible
 
The North American MSAT system will bring mobile satellite services to the communications industry. The system is described as it relates to the mobile unit. The Westinghouse unit, the Series 1000 Mobile Phone, is designed to render optimum performance at a low per unit cost
 
Aiming at actual evaluation of IMT-Advanced system performance using field tests, this paper presents a developed IMT-Advanced testbed system with transmission bandwidth of 100 MHz. IMT-Advanced supports the "new capability of systems beyond IMT-2000" as indicated by the ITU-R van diagram [1] and requires a peak data rate of 1 Gbps with low mobility. In consideration of the enhanced IMT-2000 systems undergoing standardization, orthogonal frequency division multiple access (OFDMA) with multi-input multi-output (MIMO) are also promising technologies in the IMT-Advanced system. In addition, in order to meet the requirements for IMT-Advanced, the system seems to have about 100 MHz bandwidth with the aid of MIMO transmission. The developed system is based on the above prediction regarding the IMT-Advanced era, which is a more reliable prediction compared with previous studies, and the goals of this development are to provide a more realistic transmission performance, judgment criteria for operators introducing new air interfaces, and to explore new applications. In addition, the testbed enables us to conduct feasibility studies of rotational OFDM (R-OFDM) and the twin turbo decoder, which is our previous work [2] [3]. This paper performs pre-experiments before field tests, and verifies that the testbed transmits signals with 100 MHz bandwidth and the coverage providing a throughput of more than 100 Mbps without MIMO will reaches about 650 m.
 
This paper investigated the PER and throughput performance of known bits insertion scheme for turbo code in 100 Mbps OFCDM(orthogonal frequency and code division multiplexing) in AWGN and multipath Rayleigh fading channels. The method 1 in which the information rate is reduced by replacing information bits by inserted known bits gives 8% throughput increase. The method 2 in which the information rate is fixed irrespectively of the number of inserted known bits by changing the number of punctured bits in order to get the fixed total FEC coding rate also gives PER and BER improvement compared with the conventional turbo code without known bits insertion when the number of inserted known bits are optimized.
 
Propagation measurements were performed in an indoor radio environment at 2.4 GHz, 4.75 GHz, and 11.5 GHz using a coherent measurement system consisting of an HP synthesized sweeper and a network analyzer. The three frequencies are compared by evaluating the RMS time delay spread and path loss characteristics. Such frequency comparisons in an indoor radio environment are reported
 
The author describes experiences with experimental 460-MHz and 1300-MHz wireless data networks operated within adjoining multistorey steel-reinforced office-type buildings. The experiments have been conducted using a single fixed station and portable stations at various locations within the buildings. The fixed station was moved to compare locating it within a wiring closet or near terminal equipment. The fixed station location was also varied among the floors of the building to compare relative performance. Station transmitter and receiver parameters, including transmitter power, receiver sensitivity, and antenna feedline gain, varied. Antennas compared include standard λ/4 groundplane, discone, and slot antennas. For operation between the floors, once the power was sufficient to achieve link integrity, operation was reliable. Positional fading was noted, however. Link operation was satisfactory for normal usage
 
A format designed to allow the operation of the protocol MPT 1327 at 900 MHz is presented. This protocol presents a few problems. One problem is that it is based on the existing signaling format MPT 1317, designed to operate in the frequency margin of 50 to 500 MHz. This limit is due to the low bit rate of the transmission (1200 bauds indirect modulation using fast frequency shift keying (FFSK)). Time diversity is proposed, due to the inherent simplicity of the solution. A novel signaling format is discussed which permits the extension of the use of protocol MPT 1327 to the 900 MHz band with the same reliability within +1 dB as the method applied in lower frequencies (150 MHz). This is done in a simple way, changing the method of modulation of the subcarrier from FFSK to PSK (phase shift keying) to double the bit rate, and using hard time diversity in the channel. Some simulations and experimental tests that show the validity of the approach are presented
 
A significant problem in the tracking of multiple user channels is described for a receiver that implements joint demodulation. It is observed that channel switching, where a channel tracker mixes the channels of multiple co-channel signals, degrades the performance of the receiver for medium to high speed mobiles. When a channel switch occurs, the channels of the users are tracked well, but channels are assigned to the wrong users. Consequently, from that point on all the detected symbols for a user of interest are incorrect, since they belong to another user. The tolerance of various channel tracking algorithms to this channel switching problem is discussed. The performance of the joint channel trackers is evaluated along with joint demodulation of co-channel signals for IS-136 mobiles
 
We present uplink simulation results comparing four-element adaptive arrays with a six-sector antenna system and a fixed multibeam (four 30° beam with two-branch diversity per beam in each 1200 sector) antenna system using an IS-136 TDMA modulation format and slot structure. The results consist of the capacity improvement (i.e., frequency reuse reduction) of these antenna systems over the baseline antenna system using the, simulated bit error rate (BER) as the basis of comparison. The baseline antenna system was assumed to be a typical three-sector antenna system employing two-branch spatial diversity in each sector. Simulations were run for two different cell sizes, two Doppler spread values, and multiple reuse scenarios. The results show that substantial interference suppression gains can be obtained in an interference-dominated system using adaptive antennas. This improvement allows a reduction in the frequency reuse pattern from seven to three. In contrast a simple six-sector system is found to be limited to a frequency reuse of four. The fixed multibeam antenna can achieve similar reuse patterns but with poorer performance and requires twice as many antenna elements. It is noted that the simulation results presented here are for the uplink only, similar downlink gains must be supported in order to achieve the overall capacity improvement
 
This paper evaluates the signaling capacity of the digital control channel (DCCH) on both downlink and up-link on the basis of the short message service (SMS), the number of mobile stations (MS) in a paging cluster and the SMS transaction rate per MS. Performance figures such as voice call setup message failure rate, SMS failure rate, and MS registration failure rate are assessed as a function of different loading factors. Simulations show that the down-link SMS traffic has no impact on voice call setup procedures if a higher priority is assigned to voice call setup messages. However, the up-link SMS traffic can impact voice call set up capability if the up-link SMS transaction rate is high. Simulations show that for the same SMS failure rate, the up-link DCCH can handle more SMS transactions per MS than the down-link DCCH. The impact of the number of MSs within a paging cluster on the SMS failure rate can also be significant. This paper investigates the relationship between the number of MSs in the paging cluster, the SMS transaction rate per MS, and the down-link SMS blocking rate
 
This paper evaluates the capacity of the EDGE concept. To vouch for a high simulation accuracy, a novel interface between link and system simulations is used, where multipath fading is included on a system level. This allows detailed performance analyses with and without frequency hopping, as well as for different channel types. The presented results show that spectral efficiencies exceeding 0.45 bps/Hz/site and user data rates exceeding 384 kbps are achievable with EDGE. Compared to standard General Packet Radio Service (GPRS), these figures are more than doubled
 
In this paper, we investigate the capacity and quality gains for the downlink of an ANSI-136 system when handsets equipped with co-channel interference cancellation are deployed together with base stations employing array antennas. We find that the two capacity-enhancing techniques complement each other very well. Cell sectorization and beamforming increase interferer strength disparity which is exploited by an interference cancelling receiver Compared to a 7/21 re-use system with conventional receivers, the capacity can be almost tripled by means of four fixed beams per sector and two-user joint detection receivers for a slowly-varying flat fading environment
 
We describe the algorithms, implementation, and laboratory performance of a real-time four element adaptive antenna array testbed for the uplink of a 1.9 GHz IS-136 PCS base station. Using our enhanced direct matrix inversion algorithm, experimental results show nearly a 6 dB higher gain at a 10<sup>-2</sup> bit error rate (BER) with four versus the typical two receive antennas and operation at close to a 10 <sup>-2</sup> BER even with an interferer of equal strength to the desired signal at 60 mph fading rates, These results demonstrate the feasibility of using adaptive arrays to increase both the range and capacity of TDMA cellular systems
 
BellSouth has proposed a modification to the IS-136 digital cellular standard, which they refer to as Advanced Vocoder Idle Channel Exploitation (ADVICE), in which base stations can transmit auxiliary coded (redundant) bits on otherwise unused time slots to assist certain subscriber units (SUs). We investigate two aspects of ADVICE: (1) adaptive redundancy schemes by which auxiliary bits are generated, and (2) autonomous detection mechanisms by which the SUs detect the presence of such auxiliary bits without external signaling
 
The advent of second and third generation cellular systems forces cellular operators to face a considerable increase in the signaling traffic over their mobile networks. Service providers are therefore required to have appropriate planning tools in order to maintain adequate service quality levels. This paper presents a proposal of a simulation architecture for the analysis of signaling in GSM and IS41/136 mobile cellular networks. Procedures like power up, power down, call setup, handover and location updating are implemented. The simulation tool CELSA (cellular signaling analyzer) has implemented this architecture. Simulation results for exchanged signaling load in an example network architecture are presented
 
IS-136+ aims to increase the data rate of IS-136 by using higher modulation formats such as 8-PSK or 16-QAM. It is necessary to adaptively switch between these formats to maintain optimal throughput as the SNR varies. Adaptive modulation is a non-trivial task in practice, because accurate SNR measurements are required, the interference may change more quickly than the feedback round trip, and the optimal switching points are a function of the mobile speed. As an alternative, we present an incremental redundancy ARQ retransmission scheme that not only significantly reduces the dependence on mode switching but also increases the average throughput by 20%
 
The U.S. Government is working with cellular/PCS standard bodies to develop bearer service option modes that will enable secure end-to-end digital voice between cellular handsets and existing STU-III (Secure Terminal Unit, 3rd generation) phones. A requirement is that handsets be able to reliably detect brief analog “go-secure” signaling sent by a STU-III as it attempts to transition from plain voice to encrypted voice mode, especially under conditions of fading errors. A simulation experiment is designed and conducted, demonstrating the feasibility of detecting such a proposed bearer option request under many environmental conditions
 
For the IS-136 digital PCS standard, downlink performance can be improved via the use of multi-beam arrays to statistically reduce interference at the mobile handsets. Adopting this downlink approach, it is then desirable to use the same antenna configuration for uplink reception for cost and space considerations. However, this presents a potential problem due to the limited diversity gain available from beamforming arrays, and a careful choice of the antenna configuration must be considered. In this paper, we examine this issue of maintaining acceptable uplink performance while implementing multi-beam arrays in the downlink for the IS-136 system. Specifically, different multi-beam array and diversity antenna configurations are compared using bit error-rate (BER) performance which allows an appropriate selection of the antenna configuration
 
This paper provides an overview of the flexible, high performance Packet Data Channel (PDCH) 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. The detailed design of the packet channel feedback (PCF) for the uplink medium access is described in a companion paper.
 
In previous work, techniques for improved end-user data rate extensions to the IS-136 North American TDMA standard were presented. These techniques were studied for operations in an indoor environment, particularly focused on the downlink (base station to terminal) channel. The indoor channel, with its slow fading characteristics, places special constraints on the system design, which were addressed through handset preselection antenna diversity and improved coding techniques. The work presented in this paper is twofold: to be able to demonstrate a complete end-to-end system, an enhanced IS-136 uplink had to be added to the prototype, leading to investigation of different methods of timing synchronization and diversity combining. In addition, previous standards activities have extended the scope of the original work to address operation in outdoor cellular environments where other receiver techniques were investigated
 
This paper addresses the flexibility of ANSI 136, it's RTT proponent UWC 136 and it's application to dual frequency band operation within the same market and with the ability to provide differentiated access and incremental capacity augmentation. This paper is based upon real implementation experience using parameters within ANSI 136 and hierarchical cell structures in Toronto, Canada
 
The forward and reverse link capacities of CDMA2000 and IS-136 are evaluated when they are overlaid. It is assumed that IS-136 support mainly voice services and that CDMA2000 support different services with different rates and quality requirements. Multicode and variable processing gain are studied. Moreover, as CDMA2000 can use 1.25 MHz and 5 MHz of dispersion bandwidth in the 25 MHz cellular bandwidth it is possible to have 20 and 5 frequency allocations with different reuse patterns as in FDMA and TDMA cellular systems. This idea allows us to have very high capacity in the CDMA system with the installation of less equipment in comparison with the universal frequency reuse
 
Several forward error correction (FEC), interleaving and automatic repeat request (ARQ) schemes are evaluated for transmitting packet data over IS-136 TDMA. The objective is to identify the combination of FEC, interleaving and ARQ that provides maximum data throughput at reasonable computational complexity. The FEC schemes considered are rate-n/n+1 punctured convolutional codes, long constraint length convolutional codes and punctured turbo codes. The ARQ schemes considered are ARQ with majority voting, ARQ with metric combining and ARQ with code combining (or Type III ARQ). The performance of these techniques when used with one-slot and two-slot interleaving is studied. Results show that highest throughput is achieved when a rate-5/6 convolutional code is used with one-slot interleaving and Type III ARQ scheme
 
Performance of an IS-136 cellular system is evaluated to determine the capacity enhancement and the communication quality improvement that can be achieved with base station multibeam adaptive antennas. Using adaptive antennas to receive and transmit in narrow beams, improves the C/I in both uplink and downlink, since interference is rejected in the uplink and less downlink interference is spread. System performance is evaluated by means of system level simulations focused on the downlink C/I distribution. Beamforming on a carrier basis and on a time slot basis are studied corresponding to IS-136 Rev. A and potential Rev. B mobile stations, respectively. The main conclusion is that introducing low complexity adaptive antenna systems can give gains sufficient for a 4/12 re-use within the existing IS-136 specification. In comparison, a 7/21 frequency re-use plan is required for acceptable quality with conventional sector antenna technology. If the beamforming gain is utilized to maximize the amount of served traffic, system capacity can be enhanced by more than 100% with preserved or increased communication quality
 
Top-cited authors
L. Hanzo
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Jaap van de Beek
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