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- Capacity Analysis in a Multi-service Mobile Broadband SystemPublication . Velez, Fernando J.; Correia, Luis M.Multi-service traffic engineering will be a key aspect in cellular planning for Mobile Broadband Systems, the feasibility of the aggregate traffic model being crucial. An MMPP model is proposed for the modelling of the superimposition of data and video IPP sources. Given the correspondence between applications and their bearer service components, an algorithm for the Bernoulli case of the Bernoulli-Poisson-Pascal model is used to compute the blocking probability. The supported number of users is higher in scenarios with a lower maximum load per user. In a cell with 384 channels of 384 kb/s, it varies from 20 to 26 users/cell in urban scenarios, while with 288 channels/cell, although the number of channels is only 25 % lower, the supported number of users decreases 50 %. High terminal mobility strongly degrades the performance in the roads scenario.
- Optimization Criteria for Cellular Planning of Mobile Broadband Systems in Linear and Urban CoveragesPublication . Velez, Fernando José; Correia, Luis M.This paper addresses the comparison of characteristics between the prospective allocated bands for MBS by the International Telecommunications Union, 40 and 60 GHz, and its consequences in the optimization criteria for the cellular design. The key difference between the two bands is the oxygen absorption attenuation which is negligible at 40 GHz, but presents high values at 60 GHz, larger than 10 dB for the typical reuse distance. At 60 GHz the carrier-to-interference ratio is larger, and depends on the coverage distance, while at 40 GHz this dependence does not exist. At 60 GHz lower values for the co-channel reuse factor are obtained and, as a consequence, a larger system capacity is achieved.
- Capacity trade-offs in mobile broadband systems using guard channels for high mobility handoverPublication . Velez, Fernando J.; Correia, Luis M.Models allowing the study of the influence of coverage distance and mobile velocity on the supported traffic and on the new calls traffic linear density are examined, and results are obtained for typical scenarios in a mobile broadband system (MBS) with a linear coverage geometry. In order to cope with handover failure probability requirements, the use of guard channels for handover is assumed, mainly for high mobility scenarios. For these scenarios one concludes that there is a degradation in system capacity because, for the typical coverage distances foreseen for MBS, the new calls traffic linear density is one order of magnitude bellow the values obtained for the pedestrian scenario (where it is approximately 15 Erlang/km), decreasing from 2.47 Erlang/km, in the urban scenario, down to 0.84 Erlang/km, in the highway scenario, when two guard channels are used.
- Influence of Traffic from Mobility on the Microcellular Coverage Distance in Mobile Broadband SystemsPublication . Velez, Fernando J.; Correia, Luis M.Models allowing the study of the influence of coverage distance and velocity on the supported traffic and on the new calls traffic linear density are examined, and results are obtained for typical scenarios in a Mobile Broadband System (MBS) with a linear coverage geometry. For situations without using guard channels for handover, for a fixed bounding value for the blocking probability, the new calls traffic linear density has been analyzed, increasing with the decrease of the coverage distance R, and being upper limited by a value which depends on the characteristics of the mobility scenario. However, call-dropping probability requirements also need to be fulfilled, leading to a new calls traffic linear density that only increases with the decrease of R down to an optimum value of R, and being lower for scenarios with higher mobility. This situation leads to limitations in system capacity for lower values of the coverage distance, mainly for high mobility scenarios.
- New Calls Traffic Performance in Microcellular Mobile Broadband Systems with High Mobility HandoverPublication . Velez, Fernando J.; Correia, Luis M.The maximisation of system capacity in Mobile Broadband Systems (MBSs) is addressed via an approach for traffic analysis that considers different scenarios for the mobility of terminals and two different types of services: short and long duration ones. For short duration services, the maximum of the new calls traffic linear density occurs for the typical coverage distances, R, of MBS, i.e., 100-350 m, except for the highways scenario, where it occurs for R = 500 m. However, for long duration services, these maxima are obtained for Rs approximately four times the previous values, new calls traffic linear density being 16% lower; feasible values, lower than the optimum ones, are obtained for lower coverage distances in high mobility scenarios. The use of guard channels for handover improves system performance only for short duration services, 2 being the recommended value for the number of guard channels in the considered cases.
- Cost/revenue optimisation in multi-service mobile broadband systemsPublication . Velez, Fernando J.; Correia, Luis M.Multi-service traffic has a strong impact in mobile broadband systems (MBS) revenues, allowing one to obtain merit functions for optimisation purposes. A 'net cost' model is presented for the design trade-offs between re-use pattern, K, the coverage distance, R, and the spectral efficiency, S/sub ef/(R). It allows for the determination of the revenue per basic channel, R/sub 384/, that achieves a given value for the annual profit per kilometre. Comparing the urban with the roads scenarios for R=100 in and K=2, whereas (S/sub ef/)/sub TOT/=32.2 and 15.2%, R/sub 384/ has to be 0.005 and 0.045 #/min, respectively, i.e., the prices in the roads scenario (with higher terminal mobility) have to be around one order of magnitude higher than in the urban one.
- Teletraffic Engineering in UMTS FDD Mode NetworksPublication . Caramês Garcia, Miguel; Velez, Fernando J.; Correia, Luis M.This paper presents a tool for multi-service traffic engineering in UMTS FDD mode. For each of the WCDMA system scenarios, the power restrictions and a given mixture of symmetric applications are considered. The maximum number of supported codes was obtained by previous simulations, taking into account carrier-to-interference constraints, leading to a given available data rate per cell. Given the spread-factor, with the basic resource being considered of 15 kb/s, the various applications request a certain number of basic code channels. A standard algorithm was used to compute each application’s blocking probability, Pb, as a function of the fraction of active users in cells. In the urban1 scenario (20 % data at 40 kb/s plus 80% voice), using one carrier per cell, UMTS can support 26 speech users plus 7 data users for Pb = 2 %. If two carriers were used, it would support 60 speech users and 14 data users. In the urban2 scenario, as data at 320 kb/s is considered, system performance degrades, which can only be overcome by using three carriers per cells, which seems impracticable in an actual system. The consideration of terminal mobility leads to a slight decrease on the number of supported users.
- Multi-service Traffic for Mobile Broadband Systems in Presence of MobilityPublication . Velez, Fernando J.; Correia, Luis M.Multi-service traffic engineering will be a key aspect in cellular planning of Mobile Broadband Systems (MBS), allowing to obtain merit functions for optimisation purposes. MBS will serve applications via different service components, with different data rates and average durations, user mobility having impact on the handover failure probability threshold. While in the business city centre, and other urban scenarios, mobility has no significant effect, it affects the supported traffic in main roads; a reduction of 31 % existing in the 432 channel/cell case, relatively to the situation of absence of mobility.
- Impact of Mobility in Mobile Broadband Systems Multi-service TrafficPublication . Velez, Fernando J.; Correia, Luis M.Multi-service traMc engineering has a strong impact in Mobile Broadband Systems (MBS) revenues, and it will allow one to obtain merit functions for optimisation purposes, a key aspect in cellular planning. MBS applications have access to different service components, with different data rates and average durations. Fast mobility has an important impact in handover failure probability, hence, in system capacity. While in the business city centre and other urban scenarios mobility has no significant effect, it affects the supported traffic in main roads. A reduction up to 54 % may come as a consequence.
- Traffic from Mobility in Mobile Broadband SystemsPublication . Velez, Fernando J.; Correia, Luis M.Models allowing the study of the influence of coveragedistance and velocity on the supported traffic and on thenew calls traffic linear density are examined, and resultsare obtained for typical scenarios in a Mobile BroadbandSystem (MBS) with a linear coverage geometry. For systemswithout guard channels for handover, for a fixed boundingvalue for the blocking probability, the new calls traffic lin-ear density was analyzed, increasing with the decrease of themaximum coverage distance, R, being upper limited by avalue which depends on the characteristics of the mobilityscenario. However, call-dropping probability requirementsalso need to be fulfilled, leading to a new calls traffic densitythat only increases with the decrease of R down to an opti-mum value of R, and being lower for scenarios with highermobility. These optimum values of R are higher for scenar-ios with higher and higher mobility, leading to limitations insystem capacity, mainly for high mobility scenarios. Inorder to resolve these limitations, the use of guard channelsfor handover is studied, particularly for high mobilityscenarios. For these scenarios one concludes that there is adegradation in system capacity because, for the typicalcoverage distances foreseen for MBS, the new calls trafficlinear density is one order of magnitude below the valuesobtained for the pedestrian scenario (where it is approxi-mately 15 Erlang/km), decreasing from 2.47 Erlang/km, inthe urban scenario, down to 0.84 Erlang/km, in the highwayscenario, when two guard channels are used.