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Forum Post: RE: Wht's the duration or period for UE decode the Primary SYNC signal.

John McKeague — Fri, 04 May 2012 21:38:00 GMT

As Chandrasekhar said, the timing is fixed in the standard. So if the UE is in good RF conditions it will be able to decode both PSS and SSS within the 5 ms + processing time. Of course, if RF is bad it may take much longer.

Forum Post: RE: Soft HO and Frequency RF

Chandrasekhar — Fri, 04 May 2012 13:37:00 GMT

Hi Yaseein

In fact soft handover was considered in the earlier LTE releases for cells having 1.1 reuse. But later releases removed it. Maybe the reason could be, it may require receivers like RAKE in UE which is used in W-CDMA. This may increase the complexity of UE design. My guess is as BW increases , the rake receiver design becomes complex and hence ....

The Use of 1.1 is to have higher spectral efficiency. Even with use of 1:1 the interference at cell edges can be mitigated by using ICIC fetaures.

Forum Post: Idle mode Mobility ( Reselection) Between FDD and TDD

pkt — Fri, 04 May 2012 09:41:00 GMT

Hi Experts ,

I would like to know the reselection between FDD & TDD modes in LTE . Is it possible ? Is it developed in Recent Versions ? Whether the Spec allowing the above mobility mode ?

Regards

PKT

Forum Post: RE: Regarding MAC- Random access

John McKeague — Thu, 03 May 2012 22:29:00 GMT

Its usually an RRC-Connection-Request message. The largest parameter in this message is a UE identity which is used for contention resolution. One option for this identity is a 40 bit random number. One other parameter, the establishment cause, along with headers amount to a total requirement of 56 bits.

Forum Post: RE: Why can't we use 64 QAM modulation technique in UMTS technology?

John McKeague — Thu, 03 May 2012 21:59:00 GMT

Many technologies improve over time. UMTS does now support 64QAM with HSPA+ . And LTE may one day support 256QAM.

Forum Post: RE: LTE GTP Tunnels Purpose

John McKeague — Thu, 03 May 2012 21:42:00 GMT

Tunnels are needed for mobility. Tunneling is needed and used in all mobile technologies including UMTS, GPRS, EVDO and WiMAX. In LTE, the UE's IP address is anchored in the P-GW and so GTP tunnels are used to carry the UE's packets to and from the P-GW, via eNB and S-GW.

If the eNB owned the UE's IP address then we wouldn't need tunnels, but then the UE would lose its IP address when it moves away from the coverage of that eNB.

Forum Post: RE: Regarding DRB mapping

John McKeague — Thu, 03 May 2012 21:32:00 GMT

Hi Adnan, your question is a little confusing but I think I understand what you are asking. Whether we are talking about UL or DL traffic the answer is similar, but lets focus on DL. Lets say, in a particular subframe, that a UE, which is browsing the web and on a VoIP call, finds some number of resource blocks (RBs) assigned to it. These RBs contain only one MAC layer PDU. However, the MAC layer PDU may contain one or more MAC SDUs, each SDU corresponding to one of the application flows - i.e. web pages or Voice packets in our example. (note: the MAC SDU may be for other things also but w will ignore these for simplicity). Associated with each MAC SDU is a subheader which contains a logical channel ID (LCID). And a LCID maps one-to-one with a DRB ID. So in this example, the resource blocks may contain only browsing data, or only voice packets, or both. The MAC layer can multiplex data from multiple DRBs into a single MAC PDU which is sent to the UE in one or more resource blocks.

Please let me know if this answers your question.

Cheers,

john

Forum Post: RE: does PRACH interfere with the PRACH of adjacent cell

samratps — Thu, 03 May 2012 17:03:00 GMT

thank you sir,

And how about the PRACH and adjacent cells data channel.. there will be interference right??? how to avoid that?

Forum Post: RE: RBs and No. of UEs

YASEEIN — Thu, 03 May 2012 00:01:00 GMT

Thanks a lot John for this great detailed answer.

Yaseein

Forum Post: RE: EPS/RRC bearer identities after Service Request

John McKeague — Wed, 02 May 2012 21:07:00 GMT

Yes indeed the mapping may change when the UE transitions to CONNECTED mode after receiving a page in IDLE mode, or for that matter any time the UE transitions from IDLE to CONNECTED.. When the UE goes idle the eNB it was connected to will release all context on the mobile (perhaps after a small delay). So after reconnecting the eNB gets its information about the UE's EPS bearers from the MME and will send an RRC Reconfiguration message to the UE to setup SRB2 and some number of DRBs corresponding to the list of active EPS bearers. given to it by MME. The eNB is free to pick whatever DRB IDs it desires for each of the EPS bearers. Note also that it could be a different eNB if the UE has been mobile, so in this case it would be impossible to use the same DRB IDs as before.

thanks for the question. I hope this helps.

John

Forum Post: RE: How can I extract MCC and MNC from PLMN-ID?

MShetty — Wed, 02 May 2012 04:35:00 GMT

Hi Shiva,

Thank you for the detailed explanation :-)

Regards,

Shetty

Forum Post: At what level i should include AVPs in S9 Request?

harsh patel — Tue, 01 May 2012 10:11:00 GMT

There are three distinct network scenarios for an IP-CAN as defined in 3GPP TS.29.213 [4]:

1. No Gateway Control session is needed. GTP is used for S5/S8 reference points.

2. Gateway Control session is needed. Two sub cases can be distinguished:

2a) S2c reference point (and then DSMIPv6 protocol) is used by a trusted non-3GPP access to access the EPC (Evolved Packet Core).

2b) Trusted non-3GPP accesses that use S2a reference point (PMIPv6 or MIPv4 protocol is used) or 3GPP access that uses PMIPv6 over S5/S8 reference points.

Now for Case-1 ( No Gateway Control session is needed. GTP is used for S5/S8 reference points) if V-PCRF want to send S9 request to H-PCRF. At what level (Command level OR SubsessionLevel) it should include AVPs received within CCR from PCEF.

Forum Post: RE: Spec which reveals Handover Confirm Message format

Cellular Expert — Mon, 30 Apr 2012 15:55:00 GMT

36.331 (see also handover signalling from TS 36.300 i.e. EUTRAN stage 2 specification).

24.301, being a NAS specification only talks in in conceptual terms in this respect ;-)

File: LTE Operations 101: Attach - Part 4

Chris Reece — Mon, 30 Apr 2012 14:46:00 GMT

Forum Post: RE: Protocol for RB

Chandrasekhar — Fri, 27 Apr 2012 11:34:00 GMT

MAC takes decision on assigning the RBs. This is passed on to physical layer which actually generates these Resorce blocks

Forum Post: RE: What is the identifier which differentiates the Global eNB Id as Macro or Home eNB id in a S1 SETUP REQUEST

Chandrasekhar — Fri, 27 Apr 2012 11:25:00 GMT

Please refer 36.413, section 9.2.1.37 and 9.2.1.38. The Home enB id is 28 bits which is nothing but cell id. This means each cell id maps one home enBid. For Macro the out of 28 bits, leftmost 20bits of 28 bits of cell identity is Macro enBid.

Forum Post: RE: About header compression in PDCP

Chandrasekhar — Fri, 27 Apr 2012 11:08:00 GMT

In LTE the different kinds of traffic are identified by RBid at enodeB. Radio bearers are configured with all PDCP parameters like compression profiles, max CID count etc. During the EPS bearer setup, the QOS/traffic characteristics are forwarded by MME to enodeB. The RRC protocol at enodeb understands the QOS and configures the radio bearer according to QOS /traffic characteristc. This is in turn informed o UE alsio. For every packet, the enodeB wil treat the same with configured QOS/ compression parameters.

Forum Post: RE: CQI is for DL modulation or UL modulation or both??

Chandrasekhar — Fri, 27 Apr 2012 09:24:00 GMT

The MCS is applied for both UL and DL . For DL transmission, enode B allocated the MCS based on CQI report from UE.However for UL transmission enodeB allocates the grant with MCS and resource blocks etc. For choice of MCS for UL transmission , the enode B measures Demodulation reference signals, sometimes sounding reference signals, and allocattes to UE on PDCCH .

Forum Post: RE: IP CAN session

Vijay Soundararajan — Thu, 26 Apr 2012 06:09:00 GMT

Adding to Don's reply.

UE can have multiple IP can sessions based on different APN's, maximum being 11 bearers in total.

Forum Post: RE: About LTE timing advance and maximum distance between eNodeB and Mobile Terminal

Don Hanley — Wed, 25 Apr 2012 20:39:00 GMT

I think of it as two separate issues: what is the maximum range that a UE can access the eNB (which is limited by the propagation delay that the PRACH is configured to handle), and what is the maximum range at which the UE can maintain its connection (which depends on the link budget).