Radio network planning and optimisation for umts 2nd edition phần 7 pps

In the following each paragraph begins with a direct reference to requirements given therein. MIMO proposals shall be comprehensive to include techni ques for one, two and four antennas at both the base station and UE. This requirement is motivated by the fact that deploying multiple antennas in the mobile terminal or BS to support MIMO techniques is not straightforward due to concerns of cost, complex ity and visual impact. This is especially true of today’s mobile terminals, where basic products with large production volumes may have at most two antennas. Multi-mode terminals supporting, for example, WCDMA, GSM and GPS may already require several antennas even without applying MIMO processing. Macro-BSs typically employ two or four antennas, and it is expected that two-antenna BSs will dominate in number in the near future. Thus, in practice, mobile terminals and data modems may have four antennas at the maximum, while two antennas rep resent the most likely solution. For each proposal, the transmission techniques for the range of data rates from low to high SIR shall be evaluated. This is a trivial but important requirement since the gain from information MIMO greatly depends on the SIR/SNR as is seen from Figure 6.10. Especially in macro-cell environments the operating SIR/SNR in HSDPA is most of the time less than 10 dB and the practical performance differences between various diversity MIMO and information MIMO techniques need not to be as large as Figure 6.10 hints. Operation of MIMO technique shall be specified under a range of realistic conditions. The conclusion drawn from this requirement is that there should be realistic channel models for simulations. This topic has been considered in [24]. Moreover, to imitate realistic conditions implementation non-idealities should also be taken into account. The MIMO technique shall have no significant negative impact on features available in earlier releases. Let us give an example of a serious backward compatibility problem that may arise when introducing MIMO. According to present standards there are at maximum two P-CPICHs applied in UTRA FDD downlink to aid channel estimation in the mobile terminal. To support four-antenna MIMO a straightforward solution would be to define two additional P-CPICHs. However, since total transmission power in the BS cannot be increased due to network interference and capacity reasons, the transmission power per antenna needs to be ha lved when doubling the number of transmit antennas in the BS. But then UEs that are made according to earlier standard releases and can identify only two common pilot signals would receive in a four-antenna cell only half of the pilot power when compared with the pilot power that they would receive in a two-antenna cell. This would lead to serious performance losses. MIMO techniques shall demonstrate significant incremental gain over the best performing systems supported in the current release with reasonable complexity. Although the capacity curves of Figure 6.10 suggest that information MIMO would give remarkable gains over various diversity systems, it is found that – especially when the number of antennas is only two at both ends – the practical gains from information MIMO can be small in some cases [26]. Not only does increasing the number of antennas increase the gain of information MIMO, but the implementation complexity also grows rapidly and backward compatibilit y issues – such as the above-mentioned pilot design problem – need to be faced. Coverage and Capacity Enhancement Methods 363 6.10.4 Candidate MIMO Algorithms in 3GPP Standardisation The standardisation of MIMO is still ongoing and there are many candidate algorithms that are proposed by different parties. In the following sections the proposed algorithms are briefly summarised. A more detailed description and performance analysis can be found in [23] and corresponding standardisation contributions. 6.10.4.1 Per-Antenna Rate Control According to information theory results ([27] and [28]) the capacity limit for an ope n- loop MIMO link can be achieved by transmitting separately encoded data streams from different antennas with equal power but possibly with different data rates. This idea provides a background for the basic Per-Antenna Rate Control (PARC) architecture that is given in Figure 6.11 in case of N ¼ 2. PARC shows how the HS-DSCH da ta stream is demultiplexed into two low-rate streams. Both streams are turbo-encoded, interleaved and mapped onto either QPSK or 16 State Quadrature Amplitude Modulation (16QAM) symbols. Code rates and symbol mappings can vary between low-rate streams, and therefore the number of information bits assigned to each stream can be different. Symbols are further demultiplexed into a maximum of K sub-streams, where K is the maxi mum number of High-speed Physical Downlink Shared Channels (HS-PDSCHs) defined by the mobile terminal capability. After spreading these sub-streams – employing distinct Orthogonal Variable Spreading Factor (OVSF) channelisation codes denoted by OC 1 –OC K in Figure 6.11 – they are summed and modulated by a scrambling code. The resulting antenna-specific WCDMA signal is transmitted from the associated antenna. The data rates for different antennas are selected in the BS based on antenna-specific Signal-to-Interference-and-Noise Ratio (SINR) feedback. If the SINR for a particular transmit antenna is too low to support even the lowest data rate, then transmission 364 Radio Network Planning and Optimisation for UMTS MCS 1 D E M U X MCS 2 HS-DSCH Data stream Coding Interleaving Mapping Coding Interleaving Mapping OC 1 OC 2 SC SC OC K . . . Scrambling Channelisation MCS 1 D E M U X MCS 2 HS-DSCH Data stream Coding Interleaving Mapping Coding Interleaving Mapping OC 1 OC 2 SC SC OC K . . . Scrambling Channelisation Figure 6.11 Transmitter structure for per-antenna rate control. through that antenna is suspended. For this purpose the mobile terminal estimates the CSI for all antennas and sends the required information to the BS through a feedback channel. Since the Modulation and Coding Scheme (MCS) for each antenna is selected using SINR feedback, the design of feedback quantisation is an important task. In fact, quantised CSI defines a mapping onto the table giving the modulation, coding and number of spreading codes used for each transmit antenna. Since the total number of possible transport format combinations is large, a suitable subset of combinations should be designed in order to avoid large signalling overhead. 6.10.4.2 Double STTD with Sub-group Rate Control Double STTD with Sub-group Rate Control (DSTTD-SGRC) is designed for a system with 2N transmit and at least N receive antennas. The basic idea is to divide antennas into N sub-groups each containing two antennas and apply adaptive modulation and coding along with STTD-based transmission by each group to transmit data. Within the sub-group both antennas apply the same MCS but the data rates of separate groups can be adjusted independently or jointly by selection of suitable MCSs. In the framework given by present 3GPP standardisation the maximum number of transmit antennas is expected to be four and thus, at maximum, two independent da ta streams can be transmitted. DSTTD-SGRC can be viewed as an extension to conventional STTD supported by Release ’99 standards – STTD was introduced in Section 6.9. While conventional STTD employs two transmit antennas and a single data stream, DSTTD-SGRC doubles the number of transmit antennas and data streams, provided that the mobile term ibal is equipped with at least two antenna s. From this viewpoint it can be expected that DSTTD-SGRC attains good backward compatibility with previous standard releases. Figure 6.12 shows the structure of the DSTTD-SGRC transmitter when four antennas are being used. The incoming HS-DSCH data is divided into two streams by the demux module and transmitted by the first and second sub-groups. The applied Coverage and Capacity Enhancement Methods 365 MCS 1 D E M U X MCS 2 HS-DSCH Data stream Coding Interleaving Mapping Coding Interleaving Mapping STTD STTD Demux Demux Demux Demux OC 1 OC K SC OC 1 OC K SC Scrambling Channelisation MCS 1 D E M U X MCS 2 HS-DSCH Data stream Coding Interleaving Mapping Coding Interleaving Mapping STTD STTD Demux Demux Demux Demux OC 1 OC K SC OC 1 OC K SC Scrambling Channelisation Figure 6.12 Transmitter structure for double space–time transmit diversity with sub-group rate control. MCS and the number of spreading codes define the number of information bits allocated to each stream. For both streams information bits are coded, interleaved and modulated according to the selected MCS. The two symbol streams obtained after STTD encoding are then split into K parallel streams corresponding to K spreading codes. In the last stage the streams are combined, scrambled and transmitted. 6.10.4.3 Other proposed MIMO algorithms Besides PARC and DSTTD-SGRC six other MIMO algorithms are proposed in [23]. Since most of these schemes are not as well-documented as PARC and DSTTD-SGRC they are introduced here only very briefly. In Rate-Control Multi-Paths Diversity (RC-MPD) each data stream is transmitted from at least two antennas and the number of data streams is equal to the number of transmit antennas. Furthermore, a pair of data streams that share the same two antennas apply the same MCS. The basic idea is to transmit another copy of the signal after a 1 chip delay by using STTD encoding. Hence, if there are two antennas, two data streams and the corresponding symbols are s 1 and s 2 , then the transmitted signal consists of symbols s 1 and s 2 at time T and symbols Às à 2 and s à 1 at time T þT C where T C is the chip interval. The aim in the method is to achieve multi- path diversity that is orthogonalised through STTD encoding. The single-stream closed-loop MIMO is a four-antenna extension of the two-antenna closed-loop mode 1 that is supported by Release ’99 standards – it was introduced in Section 6.9. There are tw o basic problems with this method. First, only a single data stream is supported limiting achievable peak data rates. Second, for the phase reference four common pilots instead of two are needed. This leads to backward incompatibilit y with previous standard releases. Per-User Unitary Rate Control (PU 2 RC) is based on the singular value decom- position of MIMO channels. In this method transmit weights are computed based on the unitary matrix that is a combination of the selected unitary basis vector from all mobile terminals. The aim is to utilise multi-user diversity on top of MIMO transmission. In Transmit Power Ratio Control for Code Domain Successive Interference Cancella- tion (TPRC for CD-SIC) the receiver is characterised by the code domain successive interference canceller. The goal is to suppress the impact of code domain interference in addition to space–time interference. System performance is further boosted by employing the so-called ‘code domain transmit power ratio control’ that requires additional feedback signalling. The aim of the Selective PARC (S-PARC) is to improve the performance of conventional PARC. This is done by improving the feedback format of conventional PARC. Performance gains are expected especially when the number of receive antennas is smaller than the number of transmit antennas or SNR is low. Finally, in Double Transmit Antenna Array (D-TxAA) the data stream is split into two sub-streams and each sub-stream is transmitted from two antennas by applying either one of the closed-loop methods according to Release ’99. Hence, the total number of transmit antennas is four. Again the same common pilot problem as in the case of single-stream closed-loop MIMO is faced. 366 Radio Network Planning and Optimisation for UMTS Various performance results for the above-mentioned candidate algorithms have been presented during the 3GPP standardisation process. However, since there is no wide agreement concerning the mutual ranking of the candidate algorithms and even simulation assumptions are under consideration, no performance results are shown here. 6.10.5 MIMO in UTRA FDD Uplink So far, MIMO discussions in 3GPP have focused on HSDPA. However, when new services such as videophones become more popular, it is extremely important to reach high spectral efficiency in the uplink direction as well. Furthermore, if multi-antenna mobiles are deployed for HSDPA, it is important to study the gain of multiple transmit antennas in the uplink. In the UTRA framework, the feasibility of different MIMO methods varies between the uplink and downlink. While intra-cell users in the downlink are separated by different orthogonal channelisation codes, and the capacity is limited by the shortage of channelisation codes, in the uplink, different users are separated by long scrambling codes, and a single user may use the entire family of orthogonal channelisation codes. Transmit power control is an inherent characteristic of the asynchronous WCDMA uplink. Due to non-orthogonality of the users’ channelisation codes multi-user inter- ference cannot be avoided. Accurate transmit power control is indispensable to uplink performance and should be taken into accoun t when designing MIMO algorithms. In [29] simple diversity and information MIMO approaches were studied assuming the UTRA FDD fram ework. Results show that the uplink coverage and capacity of the UTRA FDD mode are significantly increased by SIMO and MIMO. While the performance increase from additional BS antennas reflects to coverage and capacity results straightforwardly, the transmit diversity gain from addition al antennas at the mobile end is relatively small. This is due to the fact that link-level power control converts the increased diversity to a decrease in required transmission power. On the contrary, if user bit rates higher than 2 Mbps are needed, the gain from information MIMO is large, because heavy code puncturing can be avoided. Thus, multiple transmit antennas should be used in the mobile terminal for spatial multiplexing rather than for transmit diversity. Furthermore, the simplest information MIMO algorithms only require minor changes to the present UTRA FDD specifications. 6.11 Beamforming Whereas higher order receive diversity improves uplink performance and transmit diversity improves downlink performance, beamforming improves both uplink and downlink performance. If the antenna array has between two and eight elements, uplink receive diversity provides approximately the same uplink gains as beamforming. However, antenna arrays with more than two elements can provide greater downlink gains than those provided by transmit diversity. This is a result of spatial filtering, which confines downlink interference to a limited angular spread. The choice of whether to use beamforming or higher order receive diversity combined with Coverage and Capacity Enhancement Methods 367 transmit diversity is dependent upon the specific radio environment as well as the maturity of each technology. 6.11.1 Mathematical Background Directing a beam in a particular direction can be achieved using a phased array antenna. A common solution is the uniform linear array, which adjusts the phase shift for each antenna element such that the desired signal sums coherently at a specific Direction of Arrival (DoA). Figure 6.13 illustrates the phase difference between two adjacent antennas of a four-element array for a DoA . The phase shift relative to the reference element increases linearly from element to element. Compensat- ing for the phase shifts corresponding to a specific DoA results in coherent summation. The phase shift at element m is a function of the inter-element spacing d,DoA and carrier wavelength . Equation (6.7) expresses the relationship: ’ m ¼ 2 Á   Á Dl m ¼ 2 Á   Áðm À 1ÞÁd Á sin ; m ¼ 1; ; M ð6:7Þ The response vector a of an antenna array with M elements describes the complex antenna weights for the beam directed towards DoA : a ¼½1; expðj Á ’ 1 Þ; ; expðj Á ’ M Þ ð6:8Þ There are two fundamental approaches to beamforming: either multiple fixed beams or user-specific beams. Orthogonal fixed beams can be generated using the Butler matrix, which defines the parallel sets of phase shifts associ ated with each beam. Table 6.22 presents the phase shifts of a four-element array used to generate four orthogonal beams. Figure 6.14 illustrates the corresponding beam patterns with respect to a hexagonal cell footprint. This figure takes account of the beam pattern of each individual antenna element. The fixed beam approach can be implemented in a relatively simple manner by integrating analogue phase shift components into the antenna pa nel. In this case multiple users are assigned to each beam. The user-specific approach to beamforming 368 Radio Network Planning and Optimisation for UMTS θ 1 2 3 4 d Antenna element ∆ l 2 Σ ΣΣ Σ Beam to DoA of θ Phase shifter ∆ l 3 Figure 6.13 Geometry of a uniform linear array for a planewave in the direction of arrival . is more complex and requires a separate response vector to be assigned to each mobile terminal. 6.11.2 Impact of Beamforming Table 6.23 presents a set of link-level simulation results comparing the uplink perform- ance gains for a range of antenna configu rations. The beamforming results correspond to the fixed beam approach rather than the user-specific beam approach. The 4 þ4 configuration implies two sets of four beams separated by polarisation diversity. The gain is presented in terms of a reduction in E b =N 0 requirement relative to two-branch receive diversity. E b =N 0 reductions improve both coverage and capacity in the uplink direction. The gain is relatively insensitive to the DoA of the mobile terminal – i.e., whether it is towards the centre of a beam or between two beams. This is a result of the angular diversity gain being at a maximum between two beams while the beamforming gain is at a maximum in the direction of a beam. In the Pedestrian A environment which exhibits only two delay spread components, the fixed eight-beam approach performs no bette r than four-branch MRC. Coverage and Capacity Enhancement Methods 369 -80 -60 -40 -20 0 20 40 60 80 -35 -30 -25 -20 -15 -10 -5 0 Orthogonal Butler Beams Azimuth angle [degrees] Relative amplitude [dB] Cell boundary Figure 6.14 Beam pattern of a four-element array based upon the Butler matrix of Table 6.22. Table 6.22 Phase shifts ’ m for the 4  4 Butler matrix. Antenna element d Beam d 12 34 [  ][  ][  ][  ] 10À135 À270 À405 20À45 À90 À135 3 0 45 90 135 4 0 135 270 405 Beamforming provides spatial filtering of down link transmit power towards the desired mobile terminal. Spatial filtering provides two benefits. First of all transmit power can be reduced by the gain of the antenna array. For example, in an ideal scenario a four-antenna array provides an array gain of 4 and the transmit powers can be reduced by a corresponding factor of 4. The second benefit of spatial filtering is the reduction in interference between users associated with different beams. This allows a significant increase in the number of users supported. The physical layer performance of the WCDMA downlink is dependent upon the mobile terminal’s ability to accurately estimate the channel impulse response and measure the received SIR. In the case of single transmit antenna configurations, the 3GPP specifications define a reliable phase reference in terms of the P-CPICH. When an operator deploys fixed beam beamforming Secondary CPICHs (S-CPICHs) are used to provide a separate and reliable phase reference for each beam. It is possible to evaluate the downlink beamforming gains based upon the mobile terminal’s reception of CPICHs [15]. Table 6.24 presents a set of simulation results for a macro-cell environment as a function of the BS antenna configuration and the angular spread of the radio environment. The angular spread at the BS antenna array has been modelled as a Laplacian distribution. The gains have been evaluated by averaging over all azimuths. The results indica te that beamforming provides an effective technique for improving downlink performance, especially in environments with low angular spread. 6.11.3 Practical Considerations The requirements of beamforming techniques have been taken into account throughout the standardisation of WCDMA. The fixed beam approach is more mature than the user-specific beam approach. Fixed beams are usually generated by analogue phase shifters. In the case of user-specific beamforming, a different beam points in the 370 Radio Network Planning and Optimisation for UMTS Table 6.23 Reduction in uplink E b =N 0 requirements provided by fixed beam beamforming and four-antenna MRC relative to the E b =N 0 requirement of a two-branch receiver for a 12.2 kbps speech service with a BLER of 1%. Antenna configuration Modified Vehicular A Pedestrian A 3 km/h 50 km/h 120 km/h 3 km/h [dB] [dB] [dB] [dB] 4-antenna MRC a 3.0 2.5 2.3 5.9 8 beams b 4.9 5.2 5.1 5.9 8 beams c 4.4 4.9 4.8 5.8 4 þ4 beams b 5.5 5.7 5.9 7.0 4 þ4 beams c 4.4 4.3 4.5 6.0 a Uncorrelated antennas. b Mobile terminal direction of arrival towards the maximum beam gain, eight RAKE fingers. c Mobile terminal direction of arrival between two beams, eight RAKE fingers. direction of each mobile terminal. User-specific beamforming necessitates the use of the pilot sequence within the Dedicated Physical Control Channel (DPCCH), which reduces link performance by 2–3 dB relative to when using the P-CPICH. The power of the DPCCH can be varied, but excessive powers lead to inefficient use of downlink transmit power and a corresponding loss in capacity. User-specific beamforming can be implemented either fully digitally or as a hybrid analogue/digital solution. The WCDMA specification favours adoption of the fixed beam approach. Reasons include the following: . Mobile terminal functions are well-specified. Beam-specific S-CPICHs can be exploited allowing standard channel impulse response and SIR estimation algorithms to be used. . Primary and secondary scrambling codes can be assigned across the beams belonging to a cell. This helps alleviate the issue of limitations in the channelisation code tree. . One or more downlink shared channels can be assigned to each beam to help improve packet scheduling for shared channels. This can lead to improved trunking efficiency. . The impact upon RRM functionality is minimal. The fixed beam approach is also attractive because of its strong physical layer performance and reasonable mobile terminal complexity requirement. The largest drawback with the user-specific approach is the increase in complexity an d the requirement for non-standard functionality. In addition, the specification for user- specific beamforming does not support transmit diversity and there is a relatively large impact upon RRM functions. Finally, the fact that user-specific beamforming does not provide significant performance gains over the fixed beam approach means that the fixed beam approach is likely to be the preferred technique for WCDMA. A significant advantage of beamforming is that the antenna array can be constructed within a single antenna radome. The relatively high gain of the array means that the vertical dimensions of the antenna panel can be reduced while maintaining service coverage and system capacity performance. Coverage and Capacity Enhancement Methods 371 Table 6.24 Reduction in downlink E b =N 0 requirement associated with fixed beam beamforming relative to a cell configured with a single transmit element. Antenna Angular spread configuration 2  6  10  20  [dB] [dB] [dB] [dB] Two-beam 2.2 2.2 2.1 1.8 Four-beam 5.1 5.0 4.5 3.7 Six-beam 6.9 6.3 5.8 4.5 Eight-beam 8.8 8.0 7.0 5.2 6.11.4 Impact of Fixed Beam Approach upon Radio Resource Management Algorithms The spatial filtering that is characteristic of beamforming means that the loading per beam varies as a function of the azimuth distribution of the traffic and multiple access interference. Mobile terminals using high data rate services tend to generate a non- uniform spatial traffic and interference distribution. The admission control and load control schemes should recognise when cell loading is non-uniformly distributed and react accordingly. The conventional power-based admission control algorithms used with standard sectorised sites can be modified to cope with the fixed beam configuration ([16]–[18]). Power-based admission control algorithms monitor received interference power as well as BS transmit power. Users are granted access to the system if both the receiver interference floor and the BS transmit power are below certain pre-defined thresholds. In the case of power-based admission control with fixed beam beamforming a new user is granted access if the angular power distribution remains satisfactory – i.e., the total BS power and interference level thresholds in each fixed beam are not exceeded. The power increase in each beam depends upon the angular spread and the DoA of the mobile terminal as well as the beam patterns themselves. Figure 6.15 illustrates a fixed beam antenna configuration with a new user attempting to access the system. If the new user is granted access to beam Pð 4 Þ then not only will the load of this beam increase but also those of beams Pð 1 Þ, Pð 2 Þ and Pð 3 Þ. This is caused by the side lobes of each beam leaking and receiving power across the entire cove rage area of the cell. Figure 6.14 shows the side lobes from a four-beam antenna array. The capacity provided by this form of admission control is greatest for uniform traffic and inter - ference loading the cell. 372 Radio Network Planning and Optimisation for UMTS BTS RNC Antenna array Angular spread of signal paths from the mobile terminal P(θ 1 ) P(θ 2 ) P(θ 3 ) P(θ 4 ) RNC Angular spread of signal paths from the mobile terminal Antenna array BS P ð 1 Þ P ð 2 Þ P ð 3 Þ P ð 4 Þ Figure 6.15 An illustration of the effective transmit and receive azimuth power spectrum from a base station configured with a fixed four-beam beamforming antenna array. [...]... gain and level of inter-cell interference Antenna side lobes are also likely to be greater for more directional antennas The soft handover overhead should be maintained at approximately 30% with the help of the relevant RRM parameters – e.g., defining the active set size and soft handover window Radio Network Planning and Optimisation for UMTS 378 Table 6.28 Typical antenna, inter-cell interference and. .. kbps data a 79 17 12 4 69.9 66.3 4 .7 1.6 39.8 40 .7 42.4 41.4 Micro-cell with transmit diversity 12.2 kbps speech 64/64 kbps data 64/128 kbps data a 64/384 kbps data a 79 17 18 7 69.9 66.3 7. 0 2 .7 37. 2 38 .7 42 .7 42.0 a Includes an activity factor ratio of 1 : 10 for uplink-to-downlink traffic channel activity interference combined with the increase in downlink channelisation code orthogonality and decrease... noise floors Therefore, in the case of UMTS the planning phases cannot be separated into coverage and capacity planning For post-2G systems data services start to play an important role The variety of services requires the whole optimisation process to overcome a set of modifications One of these is related to Quality of Service (QoS) 398 Radio Network Planning and Optimisation for UMTS requirements... Wiley & Sons, Ltd Radio Network Planning and Optimisation for UMTS 396 mobility impact on planning; hierarchical cell structures, and other special cell types; site synthesis; increasingly important role of the NMS Response time When provisioning 3G network and services the control for the access part can be divided into three levels These control levels are depicted in Figure 7. 1 The highest control... CPICH and CCCHs) 12.2 kbps speech 64/64 kbps data 64/128 kbps data a 64/384 kbps data a 233 31 17 7 75 .5 50.2 2.8 1.1 78 .1 75 .5 74 .7 75.5 ROC 1 þ 1 þ 1 20 W shared between sectors (4.5 W assigned to CPICH and CCCHs) 12.2 kbps speech 64/64 kbps data 64/128 kbps data a 64/384 kbps data a 84 11 6 2 27. 3 16.8 0.9 0.4 25.8 23.1 22.3 23.1 ROC 1 þ 1 þ 1 40 W shared between sectors (9 W assigned to CPICH and. .. scenarios Tables 6.36 and 6. 37 present air interface capacities but take no account of the limitations of the downlink channelisation code tree Table 6.38 presents these limitations for a micro-cellular environment Radio Network Planning and Optimisation for UMTS 386 Table 6. 37 Micro-cell capacities when assigned 8 W of transmit power capability, based upon an allowed propagation loss of 144 .7 dB (64 kbps... greater than that used for other counters and KPIs recorded from the network The KPIs should allow operators to evaluate whether or not system capacity limits are being approached KPIs should be defined to quantify all aspects of system capacity Example aspects of system capacity are uplink DPCH Radio Network Planning and Optimisation for UMTS 388 START Periodically collect network performance statistics... criterion and code construction IEEE Transactions on Information Theory, IT-44(2), March 1998, pp 451–460 [13] Holma, H and Toskala, A (eds), WCDMA for UMTS (3rd edn) John Wiley & Sons, 2004 [14] Andersen, S., Hagerman, B., Dam, H., Forssen, U., Karlsson, J., Kronestedt, F., Mazur, S and Molnar, K.J., Adaptive antennas for GSM and TDMA systems IEEE Personal Communications, June 1999, pp 74 –86 Coverage and. .. Packet Radio Service) networks effectively and at the same time tune 3G networks and 3G services towards valuegenerating machinery This work is supported by realistic business plans in terms of both future service demand estimates and the requirement for investment in network infrastructure These are supported by system dimensioning tools capable of assessing both the radio access and the core network. .. also the potential for introducing data services where they currently do not exist In [1] some of the issues relevant to 3G planning and management are listed: introduction of multiple services; Quality of Service (QoS) requirements; modelling of traffic distributions (e.g., traffic hotspots); Radio Network Planning and Optimisation for UMTS Second Edition Edited by J Laiho, A Wacker and T Novosad # 2006 . capacity provided by this form of admission control is greatest for uniform traffic and inter - ference loading the cell. 372 Radio Network Planning and Optimisation for UMTS BTS RNC Antenna array Angular. user-specific beamforming, a different beam points in the 370 Radio Network Planning and Optimisation for UMTS Table 6.23 Reduction in uplink E b =N 0 requirements provided by fixed beam beamforming and four-antenna. MIMO is faced. 366 Radio Network Planning and Optimisation for UMTS Various performance results for the above-mentioned candidate algorithms have been presented during the 3GPP standardisation process.