Multi Band Cell in GSM

Multi Band Cell makes it possible to mix transceivers from different frequency bands in one cell.BCCH only have to be reserved in one of the frequency bands.For the radio network this will enable both increased capacity and savings in operation and maintenance cost.
Capacity increase

GSM900 4/4/4 Erlang @GoS2% 57.8GSM1800 2/2/2 Erlang @GoS2% 24.6Total Capacity: 6/6/6 Erlang @GoS2% 104.1


BenefitsIncreased radio network capacity (Trunking efficiency).Improved radio network quality, because fewer neighbors-cells means that terminals will find the best handover candidate more often.Reduced cost for radio network handling, as there will be significantly fewer cells.

Higher spectrum utilisation
   –Freeing BCCH frequencies   –By pushing traffic to OL subcell

Reduced number of physical cells   –Transparent frequency band   –Less network complexityFewer neighbor relations & Another TS for TCH

Dynamic Overlaid/Underlaid Subcell 

EnhancementDynamic Overlaid/Underlaid Subcell is enhanced so that subcell load distribution is possible to initiate also in the overlaid subcell.

Benefit>Less Radio Network congestion>Greater flexibility in handling Multi Band Cell and Half Rate in the network




Multi Band Cell

EnhancementMulti Band Cell is enhanced to improve the handover performance in multiband cells. Thelocating accuracy for connections using the non-BCCH frequency is enhanced. BenefitImproved Radio Network performance (handover)Easier parameter handling


Antenna Configuration

LTE DL Operation Highlights: Similarities to HSPA

• Shared Channel Operation

• CDS (Channel Dependent Scheduling)
–Requires Channel Quality Information (CQI) sent on the UL
–Requires Pre-coding and Rank information sent on the UL for MIMO
• AMC (Adaptive Modulation and Coding)
–Requires informing the UE about allocated Resources
–Requires informing the UE about Modulation and Coding Schemes (MCS)
• HARQ (Hybrid ARQ)
–Uses Asynchronous adaptive retransmissions
–Uses Synchronous ACK/NAKs
–Requires ACK/NAK sent on the UL
• DL Modulation: QPSK, 16-QAM, 64-QAM

• Multiple Access Dimensions:
• DL Scheduler:
–Assigns Time/Frequency resources, rather than Time/Code resources
–May coordinate with neighbor Base Stations for interference management.
• DL Reference Signals (Pilots):
–Have fixed time duration and frequency sub-band allocations.
• ARQ runs at E-NodeB
–ARQ architecture is conceptually similar to HSPA. (It supports TM, UM, and
AM modes and retransmissions are based on status reports.)
–Optional HARQ assisted ARQ operation is possible in LTE.
• Multiple PDSCH Tx Modes
- Requires different Channel Quality Reporting, acknowledging and scheduling mechanisms

LTE ACK/NACK for PDSCH Transmissions

The UE shall, upon detection of a PDSCH transmission in subframe n-4 intended for the UE and for which an ACK/NACK shall be provided, transmit the ACK/NACK response in subframe n.

CQI/PMI/RI and ACK/NACKs multiplexing on PUCCH is possible:
• Format 2:
– CQI/PMI/RI not multiplexed with ACK/NAK
• Format 2a/2b
– CQI/PMI/RI multiplexed with ACK/NAK (normal CP)
• Format 2:
– CQI/PMI or RI multiplexed with ACK/NAK (extended CP)
ACK/NACK for PDSCH Transmissions
The UE shall, upon detection of a PDSCH transmission in subframe n-4
intended for the UE and for which an ACK/NACK shall be provided,
transmit the ACK/NACK response in subframe n.
ACK/NACKs alone can be delivered PUCCH format 1a and 1b

LTE E-UTRA UL Channels and Signals

Signals

• Demodulation Reference Signal (DM-RS)
• Sounding Reference Signal (SRS) Control
• ACK, CQI, Rank Indicator (RI), Precoding support (PMI)
• Scheduling Request (SR)
• Single “control” channel
- Physical Uplink Control Channel (PUCCH) Data
• Unicast data and data + control
• Single “data” channel
- Physical Uplink Shared Channel (PUSCH) Random access
• Preamble sequences in Physical Random Access Channel (PRACH)

LTE E-UTRA Uplink Reference Signals

•Two types of E-UTRA/LTE Uplink Reference

Signals:
• Demodulation reference signal
– Associated with transmission of PUSCH or PUCCH
– Purpose: Channel estimation for uplink coherent demodulation/detection of the uplink control and data channels
– Transmitted in time/frequency depending on the channel type (PUSCH/PUCCH), format, and cyclic prefix type
• Sounding reference signal
– Not associated with transmission of PUSCH or PUCCH
– Purpose: Uplink channel quality estimation feedback to the uplink scheduler (for Channel Dependent Scheduling) at the e-NodeB
– Transmitted in time/frequency depending on the SRS bandwidth and the SRS bandwidth configuration (some rules apply if overlap with PUSCH and PUCCH)

Notes
•The same set of base sequences is used to generate demodulation and sounding reference signals
•The base sequences and the reference signals are derived from Zadoff-Chu sequences
•Cyclic shifts can be applied to a base sequence to obtain multiple reference signal sequences

LTE Physical Uplink Control Channel (PUCCH)

Physical Uplink Control Channel (PUCCH)

The physical Uplink control channel, PUCCH, carries Uplink control information (UCI), and is never transmitted simultaneously with the PUSCH from the same UE.
A maximum of 4 resource blocks are reserved for PUCCH in this example. The physical resources used for PUCCH depend on parameters given by higher layers.
The following combinations of Uplink control information (UCI) are supported on PUCCH:

  > HARQ-ACK using PUCCH format 1a or 1b
  > Scheduling request (SR) using PUCCH format 1
  > HARQ-ACK and SR using PUCCH format 1a or 1b
  > CQI/PMI or RI using PUCCH format 2
  > CQI/PMI or RI and HARQ-ACK using PUCCH format
       – 2a or 2b for normal cyclic prefix
       – 2 for extended cyclic prefix

LTE Sounding Reference Signals (SRS)

 

SRS shall be transmitted at the last symbol of the subframe.

PUSCH:
• The mapping to resource elements only considers those not used for transmission of reference signals.
PUCCH Format 1a and 1b (HARQ-ACK):
• One SC-FDMA symbol on PUCCH shall be punctured.
PUCCH Format 1 (SR) and 2, 2a, 2b (CQI):
• A UE shall not transmit SRS whenever SRS collide with PUCCH format 1 (SR), and 2, 2a and 2b (CQI).

 

Sounding Reference Signals
Details about UE sounding procedure can be found in TS36.211 and TS36.213 §8.3.
The reference signal sequence shall be multiplied with the amplitude scaling factor and mapped
resource elements. The resource element mapping shall be in increasing order of first k, then l, and finally the slot number.

There are many FDD sounding reference signal subframe configurations as per TS36.211 §5.5.3.3.
The sounding reference signal shall be transmitted at the last symbol of the subframe according to 36.211.
A UE shall not transmit SRS whenever SRS and CQI transmissions happen to coincide in the same subframe.
A UE shall not transmit SRS whenever SRS and SR transmissions happen to coincide in the same subframe.
When a UE is configured by higher layers to support both A/N and SRS transmissions in the same subframe, then the UE shall transmit A/N using a shortened PUCCH format where the A/N symbol corresponding to the SRS location is punctured.