QoS (Quality of Service) in LTE

QCI	Resource Type	Priority	Packet Delay Budget	Packet Error Loss Rate	Example Services
1	GBR	2	100ms	10-2	Conversational Voice
2		4	150ms	10-3	Conversational Video(Live Streaming)
3		3	50ms	10-3	Real Time Gaming
4		5	300ms	10-6	Non-Conversational Video (Buffered Streaming)
5	Non-GBR	1	100ms	10-6	IMS Signalling
6		6	300ms	10-6	Video(Bufered streaming) TCP-based (eg. www, e-mail, chat, ftp, p2p file sharing, progressive video,etc)
7		7	100ms	10-3	Voice, Video(Live Streaming) Interactive Gaming
8		8	300ms	10-6	Video(Bufered streaming) TCP-based (eg. www, e-mail, chat, ftp, p2p file sharing, progressive video,etc)
9		9

Peak Data rate calculation in LTE.

1 frame = 10 subframe = 10ms

1 subframe = 2 slots = 0.5ms

1 slot = 12 sub carriers & 7 symbols

&& 1 slot = Resource Block

Therefore 1RB = 12 x 7 = 84 Resource Elements

Bandwidth of 1 Resource Block = 180 Khz

Bandwidth of 1 Sub Carrier = 15 Khz (spacing)

Total RB Calculation:

10% of the total bandwidth is reserved for guard band.

Eg. 20Mhz = 18Mhz usable = 18Mhz / 180Khz = 100RB and so on.

Total Subcarrier Calculation

10% of the total bandwidth is reserved for guard band.

Eg. 20Mhz = 18Mhz usable = 18Mhz /  15Khz = 1200 subcarriers

Data Rate Calculation:

Some Parameters to be considered:

  Ø  Cyclic prefix

  Ø  Available Resource

  Ø  Modulation and coding scheme

  Ø  MIMO

Example:

20 Mhz channel bandwidth, normal CP & 4x4 MIMO

1.       Calculate the number of RE in a subframe with 20Mhz channel Bandwidth =

12 subcarriers x 7 symbols x 100 RB x 2 slots = 16800 RE’s per subframe.

Each RE carry a modulation symbol.

2.       Assume 64QAM modulation & no coding, 1 modulation symbol will carry 6bits. Therefore, total bits in a subframe (1ms)

= 16800 modulation symbols x 6bits/modulation symbol = 100800bits

Data rate = 100800bits/ms = 100.8Mbps

3.       With 4x4 MIMO, peak data rate = 4x100.8 = 403Mbps

4.       Estimating 25% overhead such as PDCCH, reference signal, sync signal, PBCH & some coding we get,

= 403Mbps x 0.75 = 302Mbps

For more accurate calculation refer to 3GPP specification 36.2.3

Modulation Scheme and coding table

0-9 MCS – QPSK – 2bit

10-16 MCS – 16QAM – 4bit

17-28 MCS – 64QAM – 6bit

29, 30 & 31 are reserved with 2, 4 & 6 bit respectively.

LTE Timers

Timer	Start	Stop	At Expiry	Recommended Value
T300	This timer is started when the UE sends RRCConnectionRequest.	Reception of RRCConnectionSetup or RRCConnectionReject message, cell re-selection and upon abortion of connection establishment by upper layers	the UE directly enters the RRC_IDLE state	200ms
T301	This timer is started when the UE sends an RRC Connection Reestablishment Request message	The timer is stopped if the UE receives an RRC Connection Reestablishment or RRC Connection Reestablishment Reject message. The timer is also stopped if the selected cell becomes an unsuitable cell.	the UE enters the RRC_IDLE mode.	200ms
T302	Reception of RRCConnectionReject while performing RRC connection establishment	This timer is stopped when the UE enters the RRC_CONNECTED mode or performs cell reselection	Informs upper Layers	4s
T303	Starts when access is barred while performing RRC CONNECTION ESTABLISHMENT for MO(Mobile Originating) calls	Upon entering RRC_CONNECTED and upon cell re-selection	Informs upper Layers
T304	Starts at the Receipt of RRC CONNECTION RECONFIGURATION message along with Mobility Control Info OR at the receipt of mobility from EUTRA command message including CELL CHANGE ORDER	Criterion for successful completion of handover to EUTRA or cell Change order is met (the criterion is specifiedin the target RAT incase of inter-RAT)	In case of cell change order from E-UTRA or intra E-UTRA handover,initiate theRRCconnectionreestablishment procedure; Incase of handover toEUTRA, perform the actions defined in thespecificationsapplicable forthe source RAT	For EUTRAN: 500ms for GERAN: 8000ms
T305	Access barred while performing RRCconnectionestablishment for mobile originating signalling	Upon entering RRC_CONNECTEDand upon cell re-selection	Informs upper Layers
T310	Upon detecting physical layer problemsi.e. upon receiving N310 consecutiveout-of-sync indications from lowerlayers	Upon receiving N311 consecutive in-sync indications from lower layers,upon triggering the handover procedure and upon initiating the connection re-establishment procedure	the UE enters the RRC_IDLE mode if the security mode is not activated. If the security mode is activated, the UE initiates an RRC connection reestablishment procedure.	1000ms
T311	Upon initiating the RRC connection re-establishment procedure	the UE selects an E-UTRAN or inter-RAT cell to camp on.	the UE enters the RRC_IDLE mode	1000ms
T320	Upon receiving t320 or upon cell (re)selection to E-UTRA from another RAT with validity time configured for dedicated priorities (in which case the remaining validity time is applied)	Upon entering RRC_CONNECTED,when PLMN selection is performed on request by NAS, or upon cell (re)selection to another RAT (in which case the timer is carried on to the other RAT)	Discard the cell reselection priority information provided by dedicated signaling
T321	starts upon receipt of measConfig including a reportConfig with the purpose set to reportCGI	Stops at either of following cases: 1. Upon acquiring the information needed to set all fields of Global CellId for the requested cell 2. upon receipt of measConfig that includes removal of the reportConfig with the purpose set to reportCGI	At expiry initiates the measurement reporting procedure, stop performing the related measurements and remove the corresponding measID

System Information Block -13 in LTE (SIB-13)

 Ø  Contains the information required to acquire the MBMS control information associated with one or more MBSFN areas

 Ø  Introduced in Release9

System Information Block -12 in LTE (SIB-12)

 Ø  Contains a CMAS notification

 Ø  CMAS notifications carry high emerygency situations and is defined for three catagories:

-Presidential Alerts (President of a geographical location can send alerts)

-Threat Alerts (Tornado/Hurricane alerts)

-AMBER Alerts (Child abduction, endangered situation)

 Ø  introduced in Release9

Information’s:

messageIdentifier	Identifies the source and type of CMAS notification
serialNumber	Identifies variations of a CMAS notification
warningMessageSegmentType	Indicates whether the included CMAS warning message segment is the last segment or not
warningMessageSegmentNumber	Segment number of the CMAS warning message segment contained in the SIB. A segment number of zero corresponds to the first segment, one corresponds to the second segment, and so on
warningMessageSegment	Carries a segment of the Warning Message
dataCodingScheme	Identifies the alphabet/coding and the language applied variations of a CMAS notification

System Information Block -11 in LTE (SIB-11)

 Ø  Contains an ETWS secondary notification

Information’s:

messageIdentifier	Identifies the source and type of ETWS notification (earthquake, tsunami warning, any emergency or test message)
serialNumber	Identifies variations of an ETWS notification. -uses various mechanisms to alert the user (display message, play a tone or vibrate, location where the message is applicable, also contains an update number which specifies whether a change is in the message content or not)
warningMessageSegmentType [last/not last]	Indicates whether the included ETWS warning message segment is the last segment of the complete segment or not
warningMessageSegmentNumber	# allows ordering of the message segments # Segment number of the ETWS warning message segment contained in the SIB. A segment number of zero corresponds to the first segment, one corresponds to the second segment, and so on
warningMessageSegment	carries actual segment of the message
dataCodingScheme	Identifies the alphabet/coding and the language applied variations of an ETWS notification

System Information Block -10 in LTE (SIB-10)

 Ø  contains an ETWS primary notification

Information’s:

messageIdentifier	Identifies the source and type of ETWS notification (earthquake, tsunami warning, any emergency or test message)
serialNumber	Identifies variations of an ETWS notification. -uses various mechanisms to alert the user (display message, play a tone or vibrate, location where the message is applicable, also contains an update number which specifies whether a change is in the message content or not)
warningType	# Identifies the warning type of the ETWS primary notification (earthquake, tsunami, etc.) and # provides information on emergency user alert and UE popup
warningSecurityInfo	# is optional, only applied when security is applied # Provides security information for the ETWS notification