Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ents in WCDMA uplink capabilities and performance in terms of higher data rates, reduced latency, and improved system capacity, and is therefore a natural complement to ĨĨSDPA. Together, the two are commonly referred to as High-Speed Packet Access (ĨĨSPA). The specifications of Enhanced Uplink can b Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2e found in [101] and (he references (herein.10.1OverviewAl (he core of Enhanced Uplink are two basic technologies used also for HSDPA -fast schedulingEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
and fast hybrid ARQ with soli combining. For similar reasons as for HSDPA, Enhanced Uplink also introduces a short 2 ms uplink TTT. These enhancement10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2DPA and Enhanced uplink, there arc fundamental differences between them, which has affected the detailed implementation of the features:•In the downlink, the shared resource is transmission power and the code space, both of which are located in one central node, the NodeB. In the uplink, the shared Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2resource is the amount of allowed uplink interference, which depends on the transmission power of multiple distributed nodes, the UEs.•The scheduler aEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
nd the transmission buffers are located in the same node in the downlink, while in the uplink the scheduler is located in the NodeB while the data buf10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2le BroadbandThis is in contrast to the downlink, where different transmitted channels are orthogonal. Fast power control is therefore essential for the uplink to handle the near-far problem.1 The E-DCH is transmitted with a power offset relative to the power-controlled uplink control channel and by Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2adjusting the maximum allowed power offset, the scheduler can control the E-DCH data rate. This is in contrast to HSDPA. where a (more or less) constaEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
nt transmission power with rate adaptation is used.•Soft handover is supported by the E-DCH. Receiving data from a terminal in multiple cells is funda10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2 discussed in the previous chapter. Soft handover also implies power control by multiple cells, which is necessary to limit the amount of interference generated in neighboring cells and to maintain backward compatibility and coexistence with UE not using the E-DCH for data transmission.•In the downl Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ink, higher-order modulation, which trades power efficiency for bandwidth efficiency, is useful to provide high data rates in some situations, for exaEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
mple when the scheduler has assigned a small number of channelization codes for a transmission but the amount of available transmission power is relat10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2erefore typically lower than for the downlink. Hence, unlike the downlink, higher-order modulation is less useful in the uplink macro-cells and therefore not pail of the first release of enhanced uplink.2With these differences in mind, the basic principles behind Enhanced uplink can be discussed.10. Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 21.1SchedulingFor Enhanced uplink, the scheduler is a key element, controlling when and at what (lata rale the UE is allowed to transmit. The higher thEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
e data rale a terminal is using, the higher the terminal's received power al the NodeB must be to maintain the Eft/No required for successful demodula10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2rom one UE represents interference for other terminals. Hence, the shared resource for Enhanced uplink is the amount of tolerable interference in the cell. If the interference level is too high.1 The near-far nroblem describes the nroblem of detectine a weak user, located far from the transmitter, w Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2henEnhanced Uplink187Figure 10.1 Enhanced Uplink scheduling framework.some transmissions in (he cell, control channels and non-scheduled uplink transmEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
issions. may not be received properly. On the other hand, a loo low interference level may indicate that UEs are artificially throttled and the full s10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ate as possible without exceeding the maximum tolerable interference level in the cell.Unlike ĨĨSDPA. where the scheduler and the transmission buffers both are located in the NodeB. the data to be transmitted resides in the UEs for the uplink case. Al the same lime, the scheduler is located in the N Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2odeB to coordinate different UEs transmission activities in the cell. Hence, a mechanism for communicating the scheduling decisions to the UEs and toEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
provide buffer information from the UEs to the scheduler is required. The scheduling framework for Enhanced uplink is based on scheduling grants sent 10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2trol the maximum allowed E-DCH-to-pilot power ratio the terminal may use: a larger grant implies the terminal may use a higher data rate but also contributes more to the interference level in the cell. Based on measurements of the (instantaneous) interference level, the scheduler controls the schedu Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ling grant in each terminal to maintain the interference level in the cell at a desired target (Figure 10.1).In HSDPA, typically a single user is addrEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
essed in each TTi. For Enhanced Uplink, the implementation-specific uplink scheduling strategy in most cases schedules multiple users in parallel. The10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ty on its own.1883G Evolution: HSPA and LTE for Mobile Broadbandlevel, this may cause non-acceptable interference to neighboring cells. Therefore, in soft handover, the serving ceil has the main responsibility for the scheduling operation, but the UE monitors scheduling information from all cells wi Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2th which the UE is in soft handover. The non-serving cells can request all its non-served users to lower their E-DCII data rate by transmitting an oveEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
rload indicator in the downlink. This mechanism ensures a stable network operation.Fast scheduling allows for a more relaxed connection admission stra10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ltiple users need to transmit in parallel. If this creates an unacceptably high interference level in the system, the scheduler can rapidly react and restrict the data rates they may use. Without fast scheduling, the admission control would have to be more conscr-valive and reserve a margin in the s Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ystem in case of multiple users transmitting simultaneously.10.1.2Hybrid A HQ with soft combiningFast hybrid ARQ with soft combining is used by EnhancEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
ed Uplink for basically the same reason as for HSDPA - to provide robustness against occasional transmission errors. A similar scheme as for HSDPA is 10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2o request a retransmission of the erroneously received transport block (NAK).One main difference compared to ĨĨSDPA stems from the use of soft handover in the uplink. When the UE is in soli handover, this implies that the hybrid ARQ protocol is terminated in multiple cells. Consequently, in many cas Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2es, the transmitted data may be successfully received in some NodeBs but not in others. From a UE perspective, it is sufficient if at least one NodcBEbook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
successfully receives the data. Therefore, in soft handover, all involved NodcBs attempt to decode the data and transmits an ACK or a NAK. If the ƯE r10Enhanced UplinkEnhanced Uplink, also known as High-Speed Uplink Packet Access (HSUPA), has been introduced in WCDMA Release 6. It provides improveme Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2not only to provide robustness against unpredictable interference, but also to improve the link efficiency to increase capacity and/or coverage. One possibility to provide a data rate of .V Mbit/s is to transmit at .V Mbit/s and set the transmission power to target a low Di-rnr rìrnho Ki I i tv Í i Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2ti flio rirrlof ‘Ì roil,' noroontl it! rifft trincniií-cinii nttotvinfEnhanced Uplink189hybrid ARQ retransmissions. From the discussion in Chapter 7.Ebook 3G Evolution: HSPA and LTE for mobile broadband: Part 2
this approach on average results in a lower cost per bit (a lower EịyỉNo) than the first approach. The reason is that, on average, less than n transmiGọi ngay
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