WCDMA Uplink Capacity and Interference Statistics of Highways Shaped Microcells with Imperfect Power Control and Finite Transmitted Power

The capacity and the interference statistics (mean and variance) of the sectors of a Cigar-, Tee-, and Cross-shaped WCDMA microcells are studied. Models of 5, 7, and 9 microcells are used to analyze the uplink capacity of the cigar-, Tee-, and cross-shaped W-CDMA microcell, respectively. The capacity and the interference statistics of the microcell are studied for different sector range and antenna side lobe levels. It is shown that the highest sector capacity is obtained when the microcell is cigar-shaped. For a cross-shaped microcell, the sector capacity is the lowest. Also it is shown that the uplink sector capacity will be very high if synchronous WCDMA is used in the uplink. To get the quasi maximum capacity, the sector range should be (0.6 – 1) km and the side lobe level of the directive antenna used in each sector should be – 15 dBc or lower.     

Uplink Multi-service Capacity and Interference Statistics of City Streets WCDMA Cross-shaped Microcells with Imperfect Power Control and Finite Transmitted Power

The multi-service (combination of more than one service) capacity and interference statistics (mean and variance) of the sectors of the street cross-shaped Wide Band Code Division Access (WCDMA) microcell are studied. A model of 21 cross-shaped microcells is used to analyze the uplink. The two slope propagation model is used to analyze the uplink. The capacity and interference statistics of the sectors are studied for different sector ranges, side lobe levels and power control (PC) standard deviation errors. It is noticed that, increasing the sector range will increase the sector capacity, reducing the side lobe level will also increase the sector capacity. Also it is noticed that, increasing the propagation exponent s ₂ will increase the sector capacity, reducing the standard deviations of the shadowing parameters σ₁ and σ₂ will increase the sector capacity and that reducing the power control standard deviation error σ_c will increase the sector capacity.

WCDMA uplink capacity and interference statistics of highways cigar-shaped microcells

The capacity and the interference statistics (mean value and variance) of the sectors of the cigar-shaped Wideband Code Division Multiple Access microcells are studied. The two-slope propagation model is used in the analysis. A model of five microcells is used to calculate the uplink capacity and interference statistics assuming highways cigar-shaped microcells. The capacity and the interference statistics of the microcell are studied for different sector range, propagation exponent, antenna side lobe levels and different standard deviation of the power control error. It is noticed that the quasi-maximum uplink sector capacity can be got when the sector range R is between 600 and 1,200 m and the sidelobe level of the directive antenna used in each sector is on the order of −15 dB.     

W-CDMA uplink capacity and interference statistics of cigar-shaped microcells in over-ground train service with imperfect power control and finite transmitted power

The capacity and the interference statistics of the sectors of the shaped Wideband Code Division Multiple Access (W-CDMA) microcells serving over-ground trains are studied. A model of five microcells is used to analyze the uplink. The capacity and the interference statistics of the microcell are studied for different antenna sidelobe levels and different sector ranges. In the study, imperfect power control and limited transmitted power are assumed. The effect of the power assigned to the uplink pilot is taken into account. It is shown that, the sector capacity depends on the train’s position. The uplink sector capacity limits (upper and lower) are presented. The lower capacity limit is given as a function of the sector range and the sidelobe level of the directive antenna used in each sector.     

W-CDMA Uplink Capacity and Interference Statistics of a Long Tunnel Cigar-shaped Microcells Using the Hybrid Model of Propagation with Imperfect Power Control

The uplink capacity and the interference statistics (mean and variance) of the sectors of the cigar-shaped W-CDMA microcell are studied. A model with eighteen sectors is used to analyze the uplink. The microcells are assumed to exist in a long tunnel with at least nine base stations. The hybrid model of propagation is used in the calculations. The capacity and the interference statistics of the sectors are studied in terms of the most important parameters: sector radius, specific attenuation factor, antenna sidelobe levels, bend losses and the power control standard deviation error.     

W-CDMA Uplink Capacity and Interference Statistics of a Long Tunnel Cigar-shaped Microcells Using the Hybrid Model of Propagation with Imperfect Power Control

The uplink capacity and the interference statistics (mean and variance) of the sectors of the cigar-shaped W-CDMA microcell are studied. A model with eighteen sectors is used to analyze the uplink. The microcells are assumed to exist in a long tunnel with at least nine base stations. The hybrid model of propagation is used in the calculations. The capacity and the interference statistics of the sectors are studied in terms of the most important parameters: sector radius, specific attenuation factor, antenna sidelobe levels, bend losses and the power control standard deviation error.     

Zero-Forcing Spatial Interweave with Greedy Scheduling

In this work, the effect of the multipath on the capacity and the interference statistics of the sectors of the highways cigar-shaped W-CDMA microcells is studied. A model of five microcells is used to analyze the uplink. The capacity and the interference statistics of the microcell are studied for different antenna sidelobe levels and different sector ranges. In the study, imperfect power control and limited transmitted power are assumed. Users are assumed to be within equally spaced buses and cars. The uplink capacity of the sector is studied assuming three types of services, namely, voice, 3G data and 3.75G data (representing the High Speed Uplink Packet Access). It is shown that, the sector uplink capacity depends on the buses and cars density within the sector. The capacity is also given as a function of the number of buses and cars within the sector.     

WCDMA Uplink Capacity of a Long Tunnel Cigar-shaped Microcells for Underground Train Service

In this paper, the capacity and the interference statistics of the sectors of the cigar-shaped WCDMA microcells are studied using the hybrid model of propagation. A model of nine microcells in a metro tunnel is used to analyze the uplink capacity and the interference statistics. The capacity and the interference statistics of the microcells in metro tunnels are studied in this work for different propagation parameters, antenna side lobe levels, sector ranges and bends losses.

W-CDMA Uplink Capacity and Interference Statistics of Rural Highways Cross-Shaped Microcells

The capacity and the interference statistics of the sectors of the cross-shaped W-CDMA cell are studied using an analytical approach. A model of 49 cells is used to analyse the uplink, which limits the capacity. The cells are assumed to exist in rural zones. The capacity and the interference statistics of the microcell are studied for different sector ranges and different antenna sidelobe levels.     

Capacity analysis for underlaying CDMA microcell/macrocell systems

The CDMA system can provide more capacity than the conventional AMPS system and the hierarchical layer of cells is required for system design in the future. However, the problem is whether the same RF channels used in a CDMA underlaying macrocell/microcell structure also obtain high capacity as in the homogeneous structure. This paper investigates the interference of uplink and downlink from both the microcell and macrocell in a hierarchical structure. Downlink power control is also considered. The results show that the capacity of microcell in a hierarchical structure is 23 per cent less than in homogeneous cells. The capacity of macrocell in a hierarchical structure decreases dramatically in proportion to the number of microcells. The capacities of the microcell and macrocell are limited in downlink, and uplink, respectively. In addition, more efforts for microcell should be made, such as more power is transmitted by microcell basestation if the same RF channel is used in a hierarchical structure. The results suggest that different RF channels are used in a two‐tier cellular environment. Copyright © 2001 John Wiley & Sons, Ltd.     

WCDMA downlink capacity of cigar-shaped microcells for long tunnels

In this paper, the Wideband Code Division Multiple Access (WCDMA) downlink capacity and the interference statistics of long tunnel cigar-shaped microcells are analyzed. The hybrid model of propagation is used in the analysis where a model of 10 cigar-shaped microcells is used. The downlink capacity is given for different sector radio R, break point distance R _b and propagation parameters (s and γ). It is found that the effect of changing the value of the propagation parameter s is very small. Also, it is noticed that, increasing the propagation parameter γ will increase the sector downlink. It is found that, the effect of changing the break point distance R _b is quasi null. Finally it is noticed that the imperfect power control reduces the downlink capacity by 4 %.     

Multiuser Detection Techniques for Hierarchical Cell Structures in CDMA Cellular Systems

CDMA-only microcell/macrocell cellular systems have traditionally suffered from the near-far problem in the microcells located near the macrocell boundary. Strong macrocell interference in these microcells disables conventional single-user detectors. The solutions currently adopted in the literature include bandwidth-consuming frequency separation between macrocell and microcell tiers and complex hybrid architectures. In this work we present the techniques for multiuser receiver design that address this problem. The preprocessing stage, called the projection stage, which projects the received signal onto the space orthogonal to the subspace spanned by macrocell users' signature sequences, is introduced. It is followed by the stage employing conventional multiuser detection (MUD) techniques. This class of detectors, called multiuser projection detectors (MPD), provides efficient protection against macrocell interference in all microcells, regardless of their location within the macrocell. The protection is optimal if the amplitudes of macrocell interferers are not known by the microcell BS. We analyze four MPDs using different MUD techniques in the detection stage, and perform performance comparison.     

WCDMA Uplink Capacity of Highways Cigar-Shaped Microcells with Incorporated HSUPA Service

The multi-service (voice, data and HSUPA) uplink capacity and the interference statistics of the sectors of the cigar-shaped WCDMA microcell are studied using a model of 5 highway microcells. The two-slope propagation loss model with lognormal shadowing is used in the analysis. It is concluded that the voice and data service are significantly affected by HSUPA users and sector capacity decreases dramatically when one of these users gets connected to a given sector or to one next to it. Also it has been concluded that the capacity decrement is highly sensitive to the location of the HSUPA users. Thus, no more than one HSUPA with a process gain of 16 can be connected to a given base station. In this case, the HSUPA user should interrupt its transmission when it is near to the sector border. No more than one HSUPA user with a process gain of 8 is permitted in a given sector and the sector next to it. When the HSUPA user is at the sector border, its transmission should be disabled.     

Modeling and computer simulation of wave propagation in linealline-of-sight microcells

The model and implementation principles governing the computer simulation of line-of-sight (LOS) microcell wave propagation are presented. Multiray propagation above a plane earth constitutes the basic model. For rural microcells, two rays are used while, for urban microcells, 10 rays are used propagating in a dielectric canyon. The model is applied to two relevant problems. In the first, control of electric field falloff with distance, r, is studied. ln the second, the advantages of switched transversal antenna diversity are demonstrated. Power falloff rates of 1/r⁴ and 1/r⁶ were obtained for simple two-element array structures. This may provide an additional interference control tool in the layout and design of microcells. The interference between the various rays propagating in lineal urban microcells results in deep nulls at various locations. The deleterious effects of these nulls can be eliminated by employing simple switched transverse antenna diversity     

Architecture design, frequency planning, and performance analysisfor a microcell/macrocell overlaying system

An innovative hierarchical microcell/macrocell architecture is presented. By applying the concept of cluster planning, the proposed sectoring arrangement can provide good shielding between microcells and macrocells. As a result, underlaid microcells can reuse the same frequencies as overlaying macrocells without decreasing the macrocell system capacity. With the proposed method, microcells not only can be gradually deployed, but they can be extensively installed to provide complete coverage and increase capacity throughout the service area. With these flexibilities, the proposed method allows existing macrocellular systems to evolve smoothly into a hierarchical microcell/macrocell architecture     

Uplink user capacity in a multicell CDMA system with hotspot microcells

The number of simultaneous users (or user capacity) supportable on the uplink of a multiple-macrocell code division multiple-access (CDMA) system with multiple "hotspot" microcells embedded within is studied. These microcells operate on the same frequency as the macrocells and are installed in regions of high user demand. It is shown that the user capacity depends on how the users are distributed among cells, and that the maximum (called the attainable capacity) occurs when all cells serve roughly the same number of users. The approach builds on a two-cell analysis published previously, for a single microcell embedded in a single macrocell. First, this analysis is expanded upon to estimate the attainable capacity for M macrocells, where the center one contains L microcells. Then the case in which L microcells are distributed randomly among the M macrocells is analyzed. In each case, the formula for attainable capacity is very simple and highly accurate (as demonstrated via simulations) up to reasonably high values of L. For example, with L microcells distributed among M macrocells, the analysis is accurate at least up to eight microcells per macrocell. The analysis and results are general with respect to cell geometries, propagation parameters, and other variables of the two-tier CDMA system.     

Introducing microcells into macrocellular networks: a case study

The performance in terms of signal-to-interference ratio (SIR), teletraffic, and spectral efficiency of a combined macrocellular and microcellular network is investigated when either both types of cells share the same channel set, or when the channel set is partitioned between the macrocells and the microcells. The analysis is for time-division multiple access (TDMA) with frequency hopping, power control, and discontinuous transmission, and the radio channel is composed of an inverse fourth-power path loss law with log-normal fading. We commence by introducing a single microcell into a hexagonal cluster of macrocells before considering clustered microcells. Both omnidirectional and sectorized cells are examined. We find that high reuse factors are required when channel sharing is employed. When channel partitioning is used, no co-channel interference occurs between the microcells and the macrocells allowing them to be planned independently. The reuse factors in the microcells and macrocells therefore do not need to be increased beyond conventional values. The outcome is that by opting for channel partitioning, the improvement in spectral efficiency compared to channel sharing is two to three times greater     

Sizing up the microcell for mobile radio communications

Within cellular mobile radio communication systems large cells have been widely deployed, with cell sizes decreasing as the number of subscribers increase. This has lead to the possibility of using very small cells, or microcells. However, the term microcell has been used to mean different things to different organisations. With much work being performed on propagation within microcells and on infrastructure issues for microcells there is now a sufficient base of knowledge to allow the introduction of these small cells. The paper defines the microcell, examines propagation modelling methods and tools, and looks at problematic areas such handover and the complexity of the infrastructure required. Finally, the future of microcells for mobile radio use is considered     

Microcells in personal communications systems

Research projects involving fiber-connected microcell base units, measurements and models of propagation in urban microcells, and radio link performance in urban microcells are summarized. Developments in microcell system issues, such as channel assignments and handoff in microcells and architectures for combining microcells with traditional macrocells, are discussed. Research on both indoor radio propagation and wireless indoor systems is reviewed     

Channel management in microcell/macrocell cellular radio systems

In this paper, we study spectrum management in a two-tier microcell/macrocell cellular system. Two issues are studied: micro-macro cell selection and frequency spectrum partitioning between microcells and macrocells. To keep the handoff rate in a two-tier cellular system at an acceptable level, low mobility users (with speed υ0 ) should undergo handoffs at microcell boundaries, and high mobility users (with speed υ>V₀) should undergo handoffs at macrocell boundaries. The mobile determines user mobility from microcell sojourn times and uses it for channel assignment at call origination and handoff. The probability of erroneous assignment of a mobile to a microcell or macrocell is shown to be significantly lower than previous approaches. We investigate the optimal velocity threshold, V₀, and propose that it may be dynamically adjusted according to traffic load. Finally, we propose a systematic way for finding an optimal partition of frequency spectrum between microcells and macrocells. This partitioning is based on the traffic load and velocity distribution of mobiles in the system