LTE E-UTRA Uplink Operation Highlights

• Link Adaptation (CDS – Channel Dependent Scheduling)
– Adaptive transmission Bandwidth
– Adaptive Modulation and Channel Coding Rate (AMC)
– Meets QoS requirements
• UL Power Control
– Intra-cell power control: the power spectral density of the Uplink transmissions can be influenced by the eNB.
• UL Timing Control
– Objective is to compensate for propagation delay and thus time-align the transmissions from different UEs with the receiver window of the eNB.
– The timing advance is derived from the UL received timing and sent by the eNB to the UE. UE uses this information to advance/delay its timings of transmissions to the eNB.
• Random Access procedure



E-UTRA UL Operation Highlights
Uplink link adaptation is used to guarantee the required minimum transmission performance of
each UE such as the user data rate, packet error rate, and latency, while maximizing system
throughput.
Three types of link adaptation are performed according to the channel conditions, the UE
capability such as the maximum transmission power and maximum transmission bandwidth, etc.,
and the required QoS such as the data rate, latency, and packet error rate, etc. Three link adaptation
methods are as follows:
􀁺 Adaptive transmission bandwidth
􀁺 Transmission power control
􀁺 Adaptive modulation and channel coding rate
Uplink Power control: Intra-cell power control: the power spectral density of the Uplink
transmissions can be influenced by the eNB.
Uplink timing control
􀁺 The timing advance is derived from the UL received timing and sent by the eNB to the UE.
The UE uses this to advance/delay its timings of transmissions to the eNB to compensate for
propagation delay and thus time-align the transmissions from different UEs with the receiver
window of the eNB.
􀁺 The timing advance command is on a per need basis with a granularity in the step size of
0.52 μs (16×Ts).

Link Adaptation differences from HSPA:
• Shared Channel Operation
– Dedicated logical channels are mapped onto shared transport/physical channels
• UL Multiple Access Dimensions:
– frequency/time/space in LTE; code/time in HSPA
• UL scheduler
– Uplink time/frequency resources are monitored/managed at the E-NodeB.
– HSPA, in contrast, monitors/manages Uplink Interference (Rise Over Thermal).
– LTE scheduler assigns UL Time/Frequency resources, rather than UL TX
Traffic/Pilot Ratios as in HSPA.
– As in HSPA, Uplink scheduling is based on Scheduling Requests (SR), Buffer
Status Report (BSR), and Power Headroom Reports (PHR).
– It may coordinate with neighbor Base Stations for Interference management
• Requires UL timing control to keep UL orthogonal

E-UTRA UL Operation Highlights (continued)
From TS36.201, transmissions with multiple input and multiple output antennas (MIMO) are
supported with configurations in the Downlink with two or four transmit antennas and two or four
receive antennas, which allow for multi-layer transmissions with up to four streams. Multi-user
MIMO, i.e., allocation of different streams to different users, is supported in both UL and DL.