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Tuesday 23 August 2016

  •  96173
  •  CO Customer Operations
  •  Thailand
  •  Bangkok
  •  Customer Service
  •  Full - Time Regular / Permanent
  •  0
  •  3 - 5 Years
  •  Bachelors Degree or equivalent
  •  Feb 9 2016
  • Nokia is a global leader in the technologies that connect people and things. With state-of-the-art software, hardware and services for any type of network, Nokia is uniquely positioned to help communication service providers, governments, and large enterprises deliver on the promise of 5G, the Cloud and the Internet of Things.  Serving customers in over 100 countries, our research scientists and engineers continue to invent and accelerate new technologies that will increasingly transform the way people and things communicate and connect.



    Plans and performs technical activities to service the customer and brings expertise to customer site on need basis.



    Plans and executes technical tasks requiring specialist skills in own professional area. Works independently with the responsibility for solving customer request cases and reporting according to processes. Identifies and solves technical problems. Shares knowledge in own professional area. May support areas by participating in emergency and 24/7 duty.



    1.Independently develop optimization plan,DT test scheme and optimization solution during RF optimization period.
    2.Instruct subcon to complete the wireless network optimization and testing work.
    3.Analyze network performance data and deal with the network performance problem.
    4.Provide RF planning&optimization solution, then evaluate the results of implementation.
    5.Write all kinds of RF planning & optimization reports.
    6.Do internal and external technical communication of RF professional knowledge. Prepare and present report to customer.
    7.As a member of wireless project, assist the project team to provide related high quality service for customer satisfactory.



    1.Familiar with WCDMA/FDD LTE/TDD LTE system arithmetic and signaling procedure. 
    2.Familiar with WCDMA/FDD LTE/TDD LTE standard, key technology and network structure. 
    3.Experience in using Nokia planning tool such as NetDim, Atoll , MUSA
    4. Proficient at the DT and data post-processing software. For example Nemo , Actix , TEMs  and so on.

Monday 22 August 2016

Location:
Markham, Ontario

Employment Status:
Permanent


Huawei Technologies Vision is to ‘enrich life through communication’. This is achieved with keen focus on our customers' market challenges and needs, providing excellent communications network solutions and services in order to consistently create maximum value for customers.
At present we have an exciting opportunity for a Telecom Operational Support System (OSS) Engineer . This position will be based in Markham, Ontario.


Full Time position, Location: Markham, ON
Summary:
The OSS (Operational Support Systems) Technical Support Engineer (TSE) is an important point of contact with Huawei’s customers, responsible to provide exceptional Customer Service while providing accurate and efficient technical support. The TSE works with external customers, product development, verification teams, project management, marketing teams, Huawei Global Technical Support Organization and contractors at Huawei and/or customer sites providing customer service and technical support for all Operational Support System products.
Desired Skills and Experience
Qualifications:
  • BS or MS in Electrical Engineering, Computer Science Engineering or equivalent with 5-7 years of related telecom engineering experience and strong focus on Operational Support Systems (OSS)
  • Strong troubleshooting capabilities and proven related working experience
  • Working knowledge on Java, Perl, Python scripting as well as north bound and south bound communication protocols
  • Strong knowledge of SNMP and similar network management protocols
  • Knowledge of or experience with WCDMA, LTE, GSM, CDMA, TDMA wireless technologies and network infrastructure (BTS, BSC, MSC, OMC, PDSN) and protocols (SS7, IS-95, IS-2000, TCP/IP).
  • Co-op or Internship work experience in a technology environment would be an asset. Knowledge of signaling analysis, call flow, cell drop analysis and/or experience with UMTS and LTE are definite plus.
  • Excellent interpersonal skills and strong written and spoken English communications skills.
  • Possess a good team spirit and have the ability to work in a fast paced and dynamic environment.
  • Self-starter, capable of taking initiative to identify and resolve problems. Able to travel up to approximately 25% of the time.
  • Able to work shift work including night / weekend periodically and irregular hours as required
Responsibilities:
  • Responsible for Wireless and Wireline OSS products including M2000, U2000, I2000 support, testing and troubleshooting.
  • Provide on-site and remote support to Canadian Operators on OSS product issues.
  • Perform upgrade, routine inspection, and system diagnosis for the live network. Troubleshoot hardware and software issues and identify network/applications issues.
  • Use TAC tools, technical knowledge, lab equipment, trouble ticket system and on-line resources for high quality and speedy customer issue resolution.
  • Provide training and technical support to colleagues and subcontractors who work for Huawei and deploy OSS hardware installation and commissioning.
  • Monitor Key Performance Indicator (KPI) and performance measurement analysis
  • Demonstrates and practices regularly the skills necessary to handle any CS and/or Technical Support call type that is routed through the center in this function.
  • Evaluate customers concerns and resolve problems to customer satisfaction.
  • Follows up with customer to ensure first call resolution and achieves and delivers 100% customer satisfaction.
  • Contribute to improvement of ticket handling and other operational quality KPIs
  • Develops and maintains healthy long term relationship with all stakeholders
  • Full compliance to cyber security rules set forth for protection of Customer and Huawei data
We thank all candidates for their interest in a career with Huawei Technologies; however only those selected for an interview will
be contacted. 
Named by Fast Company Magazine as one of the 5 most innovative technology companies in the world, Huawei Technologies provides working climate that promotes high-performance through:
- clarity of organizational and individual goals, and commitment to achieve the goals
- setting high performance standards and empowering employees to take responsibility for their work
- recognizing successful achievement of individual and team goals
- encouraging teamwork at every level, to ensure we accelerate productivity
  
Huawei Technologies Canada Co., Ltd. is an Equal Opportunity Employer.
We thank all applicants for interest in career opportunities with Huawei; only selected candidates will be contacted for interview.

Sunday 21 August 2016

Now you can use your Mobile internet data pack for 1 yearMobile data users will be able to keep their SIM active for one year from the day of last usage as regulator Trai on Friday permitted increase of validity for mobile data packs to 365 days, from the current up to 90 days.
Trai said the move will help boost usage by marginal consumers and also attract first-time Internet users.


"Requests were received in TRAI seeking longer validity for data-packs (that is Special Tariff Vouchers with only data benefits) primarily to address the concern of marginal consumers of wireless Internet who prefer lower denomination data packs with longer validity," the regulator said.
The move is aimed at those who use mobile SIMs for data services rather than for making phone calls. This will also help users carry forward their unused mobile internet quota throughout the year which generally lapses at the end of every month. Also mobile number ceases to exist if a customer does not use mobile services for continuous 90 days.

Trai said that only 31.35 crore wireless subscribers used internet out of a total wireless subscriber base of 103.37 crore at the end of March, 2016.
Thus, the penetration of wireless Internet in the country was only 30 per cent as on March, 2016. While the wireless data usage grew by about 58 per cent between January-March 2015 and January-March 2016, the wireless subscriber base, which used Internet, grew by mere 16 per cent during the period.
"It seems that the existing subscribers, having discovered the benefits of Internet usage, have increased their consumption of data (Internet), but the non-connected are not getting induced to access internet," TRAI said.
It said that the low level of literacy, low perceived utility of the internet, and non-affordability of data amongst marginal consumers were impeding the adoption of mobile internet.
The regulator felt that allowing longer validity for data packs would provide flexibility to service providers to offer innovative data products.
"The consumers, who use less of data services than average and those, who are presently not using any data services are likely to be the primary target consumers...," it said adding that the move would allow many first-time data users to go for data services.

BSNL to offer unlimited calls on Sundays from August 21Customers of state-run BSNL will be able to make free unlimited calls on any mobile or landline number in the country on Sundays from August 21.
Customers of state-run BSNL will be able to make free unlimited calls on any network today also on account of the nation's 70th Independence Day. 
"BSNL...customers will be able to make unlimited free voice calling from BSNL landline to any network mobile and landline in the country on August 15, and thereafter every Sunday," Telecom Minister Manoj Sinha said in a statement.



"This service will be available for all BSNL landline customers besides existing free calling scheme during night.
For new customers we are now providing fixed line connection for monthly rental starting Rs 49 for first six months and thereafter consumer can shift plan of his/her choice. The lowest monthly rental is Rs 99," BSNL CMD Anupam Shrivastava said.
According to official sources, details of the unlimited free calling plan will be released on August 15.


BSNL commands around 57 per cent market share with 14.35 million customers.
At present, it offers unlimited night calling on any network in the country between 9 pm to 7 am as complimentary service for all its customers.
BSNL landline connection plan starts at a monthly rental of Rs 120 per month which includes 120 free minutes of call within BSNL network during a month.
Private operator Bharti Airtel offers free unlimited calling from landline to any network in the country throughout the day at extra monthly fee of about Rs 100 per month.

Saturday 20 August 2016

NEW DELHI: Following Reliance Jio's partnership with Samsung, India's top telco, Bharti Airtel has collaborated with Samsung to offer 10 GB Airtel 4G data at the price of 1GB 4G data to Samsung J series customers.

Airtel's 'Super Powerful' offer will allow customers 9 GB of free data which would be valid for 28 days. The offer would be expiring on 31st December and can be availed over 3 recharges, available only for prepaid customers.


The biggest catch to the scheme is that the 9 GB of free data is only available as night data valid from 12 AM to 6 AM, which is the area where Jio wins as its preview offer comes free of day and night restrictions.

In mid-July, Jio had tied up with Samsung to offer unlimited 4G data with voice benefits to Samsung users for 90 days. The offer however was available on select Samsung Galaxy smartphones which excluded J series.

A senior executive at a leading south India-based cellphone retail chain said Jio's bundling scheme with Samsung has catalysed sales. "Sales of the Samsung handsets which have the Jio bundling scheme has grown by 15-20% since the launch last week," as reported by ET Telecom. Therefore, Samsung could be leveraging data bundling schemes to push sales as it worked out well with Reliance Jio. Now the company also has India's leading telecom service provider on board.

"We are delighted to extend our association with the popular Samsung J series. We believe this partnership will help customers enjoy best-in-class smartphone experience on Airtel's 4G network," said Ajai Puri, Director - Market Operations, Bharti Airtel.

Airtel had previously introduced bundled Double Data offerings with top industry players like Apple, Xiaomi, Micromax, Intex and Lava as well.
Another point of conflict between the two sides ​arose after it was revealed ​Friday ​that RIL unit Reliance Jio Infocomm was expanding its target subscriber base by extending its three-month free voice and data offer to enterprises across India under the ongoing trial run.



NEW DELHI|KOLKATA: Reliance Industries Chairman Mukesh Ambani mTelecom Secretary JS Deepak and Telecom Regulatory Authority of India Chairman RS Sharma on Friday to update them on the telecom unit's operations amid a raging war with India's largest telcos."The meeting lasted over oneand-a-half hours with the secretary," a person familiar with the matter told ET. Akash Ambani, the son of the RIL chairman who is deeply involved with the telecom unit, also attended the meeting.Another person said the meeting with the Trai chairman involved a presentation, providing an update on Reliance Jio Infocomm's operations. The company did not respond to email queries seeking comment.The meetings took place as incumbent operators Bharti Airtel, Vodafone India and Idea Cellular questioned Reliance Jio's status. Bharti Airtel Chairman Sunil Bharti Mittal had also met the telecom secretary recently.India's top carriers, through the Cellular Operators Association of India, have alleged that Jio is running full-fledged commercial services in the guise of trials and is trying to poach their subscribers.
Jio countered by saying it was following all the rules and alleged that there was an attempt to "sabotage" its entry by denying it adequate interconnection points.

This has led to a majority of calls from the Jio network dropping and delayed the commercial launch, Jio said. Its rivals said they have provided enough interconnect points and won't offer more until Jio starts commercial services.

Jio may shortly file a tariff plan with Trai, which would signal a big step towards a commercial launch, people familiar with the matter said.

Another point of conflict has emerged with Jio said to be expanding its target subscriber base by extending a three-month free voice and data offer to enterprises across India under the trial run. Besides, Jio has tied up to bundle its SIM cards with about 20 more smartphone brands.

Both moves prompted incumbent telcos, which have accused Jio of violating predatory pricing rules, to seek the intervention of the Department of Telecommunications and the regulator.

Jio has started reaching out to big and small companies to offer free SIMs with 90-day validity to holders of 4G phones of any brand, according to people familiar with the development. A Jio employee said the offer, aimed at expanding the target user base, will be rolled out for the larger general population over a period of time.

Currently, Jio's free package is available to those who buy Reliance Retail's LYF devices and users of certain 4G Samsung smartphones.

On Friday, Bharti Airtel tied up with Samsung Electronics to offer 10 GB of 4G data at the price of 1GB for customers of its J-series phones. Jio has also expanded its partnerships with other device makers such as LG, Gionee, Oppo and Vivo to offer data-bundled packages.

"There are in total 20 companies (device makers) that Jio has tied up with," another person said.

'COMMERCIAL LAUNCH'

Rajan Mathews, director general of COAI, urged Trai and DoT to look into Jio's latest moves. "They should be aware of such developments. We've already brought the matter to the attention of both DoT and Trai that this is tantamount to a commercial launch," he added.

Incumbent carriers have accused Jio of choking their networks with traffic generated from its growing subscriber base. Jio said it has 1.5 million users, while COAI estimates the figure at 2 million to 3 million. Jio's much-anticipated commercial launch is expected to disrupt the telecom market and begin a price war.

Telcos have already slashed effective data tariffs by 67% for prepaid customers and market leader Bharti Airtel has started offering free and unlimited voice with some of its data packs.

Vodafone, on Thursday announced a feature rich Vodafone RED postpaid offering with unlimited roaming, unlimited voice calling and 8 GB data– for just Rs. 1,999.  A variant of this plan is also available at Rs. 1,699 offering free roaming (incoming calls only), unlimited voice calling and 6 GB data.
To encourage more customers to enjoy the Vodafone RED experience, Vodafone also launched a series of entry level Vodafone RED postpaid plans attractively priced at Rs. 499, Rs. 699 and Rs. 999 with double data benefits and attractive talktime.

Announcing the launch of these new, feature rich Vodafone RED plans, Sandeep Kataria, Director - Commercial, Vodafone India said, “The postpaid customer’s usage behaviour has evolved significantly with higher usage of roaming and data. With the new Vodafone RED, there is no more holding back – we are offering our postpaid customers an all-in-one plan that addresses their roaming, data, and voice needs comprehensively. The built in quotas with value added benefits like priority access and a virtual relationship manager, make the Vodafone RED experience truly worry free and delightful.”
Vodafone RED Postpaid Plans:
One of the key elements of LTE is the use of OFDM, Orthogonal Frequency Division Multiplex, as the signal bearer and the associated access schemes, OFDMA (Orthogonal Frequency Division Multiplex) and SC-FDMA (Single Frequency Division Multiple Access).
OFDM is used in a number of other of systems from WLAN, WiMAX to broadcast technologies including DVB and DAB. OFDM has many advantages including its robustness to multipath fading and interference. In addition to this, even though, it may appear to be a particularly complicated form of modulation, it lends itself to digital signal processing techniques.
In view of its advantages, the use of ODFM and the associated access technologies, OFDMA and SC-FDMA are natural choices for the new LTE cellular standard.


LTE modulation & OFDM basics

The use of OFDM is a natural choice for LTE. While the basic concepts of OFDM are used, it has naturally been tailored to meet the exact requirements for LTE. However its use of multiple carrier each carrying a low data rate remains the same.

Note on OFDM:

Orthogonal Frequency Division Multiplex (OFDM) is a form of transmission that uses a large number of close spaced carriers that are modulated with low rate data. Normally these signals would be expected to interfere with each other, but by making the signals orthogonal to each other there is no mutual interference. The data to be transmitted is split across all the carriers to give resilience against selective fading from multi-path effects..
Click on the link for an OFDM tutorial


The actual implementation of the technology will be different between the downlink (i.e. from base station to mobile) and the uplink (i.e. mobile to the base station) as a result of the different requirements between the two directions and the equipment at either end. However OFDM was chosen as the signal bearer format because it is very resilient to interference. Also in recent years a considerable level of experience has been gained in its use from the various forms of broadcasting that use it along with Wi-Fi and WiMAX. OFDM is also a modulation format that is very suitable for carrying high data rates - one of the key requirements for LTE.
In addition to this, OFDM can be used in both FDD and TDD formats. This becomes an additional advantage.

LTE channel bandwidths and characteristics

One of the key parameters associated with the use of OFDM within LTE is the choice of bandwidth. The available bandwidth influences a variety of decisions including the number of carriers that can be accommodated in the OFDM signal and in turn this influences elements including the symbol length and so forth.
LTE defines a number of channel bandwidths. Obviously the greater the bandwidth, the greater the channel capacity.
The channel bandwidths that have been chosen for LTE are:
  1. 1.4 MHz
  2. 3 MHz
  3. 5 MHz
  4. 10 MHz
  5. 15 MHz
  6. 20 MHz


In addition to this the subcarriers spacing is 15 kHz, i.e. the LTE subcarriers are spaced 15 kHz apart from each other. To maintain orthogonality, this gives a symbol rate of 1 / 15 kHz = of 66.7 µs.
Each subcarrier is able to carry data at a maximum rate of 15 ksps (kilosymbols per second). This gives a 20 MHz bandwidth system a raw symbol rate of 18 Msps. In turn this is able to provide a raw data rate of 108 Mbps as each symbol using 64QAM is able to represent six bits.
It may appear that these rates do not align with the headline figures given in the LTE specifications. The reason for this is that actual peak data rates are derived by first subtracting the coding and control overheads. Then there are gains arising from elements such as the spatial multiplexing, etc.

LTE OFDM cyclic prefix, CP



One of the primary reasons for using OFDM as a modulation format within LTE (and many other wireless systems for that matter) is its resilience to multipath delays and spread. However it is still necessary to implement methods of adding resilience to the system. This helps overcome the inter-symbol interference (ISI) that results from this.
In areas where inter-symbol interference is expected, it can be avoided by inserting a guard period into the timing at the beginning of each data symbol. It is then possible to copy a section from the end of the symbol to the beginning. This is known as the cyclic prefix, CP. The receiver can then sample the waveform at the optimum time and avoid any inter-symbol interference caused by reflections that are delayed by times up to the length of the cyclic prefix, CP.
The length of the cyclic prefix, CP is important. If it is not long enough then it will not counteract the multipath reflection delay spread. If it is too long, then it will reduce the data throughput capacity. For LTE, the standard length of the cyclic prefix has been chosen to be 4.69 µs. This enables the system to accommodate path variations of up to 1.4 km. With the symbol length in LTE set to 66.7 µs.
The symbol length is defined by the fact that for OFDM systems the symbol length is equal to the reciprocal of the carrier spacing so that orthogonality is achieved. With a carrier spacing of 15 kHz, this gives the symbol length of 66.7 µs.

LTE OFDMA in the downlink

The OFDM signal used in LTE comprises a maximum of 2048 different sub-carriers having a spacing of 15 kHz. Although it is mandatory for the mobiles to have capability to be able to receive all 2048 sub-carriers, not all need to be transmitted by the base station which only needs to be able to support the transmission of 72 sub-carriers. In this way all mobiles will be able to talk to any base station.
Within the OFDM signal it is possible to choose between three types of modulation for the LTE signal:
  1. QPSK (= 4QAM)   2 bits per symbol
  2. 16QAM   4 bits per symbol
  3. 64QAM   6 bits per symbol

Note on QAM, Quadrature Amplitude Modualtion:

Quadrature amplitude modulation, QAM is widely sued for data transmission as it enables better elvels of spectral efficiency than other forms of modulation. QAM uses two carriers onth e same frequency shifted by 90° which are modulated by two data streams - I or Inphase and Q - Quadrature elements.
Click on the link for a QAM tutorial

The exact LTE modulation format is chosen depending upon the prevailing conditions. The lower forms of modulation, (QPSK) do not require such a large signal to noise ratio but are not able to send the data as fast. Only when there is a sufficient signal to noise ratio can the higher order modulation format be used.

Downlink carriers and resource blocks

In the downlink, the subcarriers are split into resource blocks. This enables the system to be able to compartmentalise the data across standard numbers of subcarriers.
Resource blocks comprise 12 subcarriers, regardless of the overall LTE signal bandwidth. They also cover one slot in the time frame. This means that different LTE signal bandwidths will have different numbers of resource blocks.

Channel bandwidth
(MHz)
1.435101520
Number of resource blocks615255075100

LTE SC-FDMA in the uplink



For the LTE uplink, a different concept is used for the access technique. Although still using a form of OFDMA technology, the implementation is called Single Carrier Frequency Division Multiple Access (SC-FDMA).
One of the key parameters that affects all mobiles is that of battery life. Even though battery performance is improving all the time, it is still necessary to ensure that the mobiles use as little battery power as possible. With the RF power amplifier that transmits the radio frequency signal via the antenna to the base station being the highest power item within the mobile, it is necessary that it operates in as efficient mode as possible. This can be significantly affected by the form of radio frequency modulation and signal format. Signals that have a high peak to average ratio and require linear amplification do not lend themselves to the use of efficient RF power amplifiers. As a result it is necessary to employ a mode of transmission that has as near a constant power level when operating. Unfortunately OFDM has a high peak to average ratio. While this is not a problem for the base station where power is not a particular problem, it is unacceptable for the mobile. As a result, LTE uses a modulation scheme known as SC-FDMA - Single Carrier Frequency Division Multiplex which is a hybrid format. This combines the low peak to average ratio offered by single-carrier systems with the multipath interference resilience and flexible subcarrier frequency allocation that OFDM provides.

Friday 19 August 2016

Features
FDD
TDD
Frame Stracture
10 ms radio frame, 1 ms sub frame
10 ms radio frame, 1 ms sub frame
Switching Points
N/A
5 ms or 10 ms periodicity
DL Control Channel
Can Schedule 1 DL and 1 UL subframe at a time
Can schedule 1 DL and multiple UL sub-frame at a time
UL Control Channel
Single Ack/Nack corresponding to 1DLsub frame
Ack/Nack corresponding to multiple DL sub frame
PRACH Preamble Format
0,1,2,3
0,1,2,3,4(Short RACH)
PRACH Configuration


Special Slot usage
N/A
DwPTS : RS, Data and Control
UpPTS : SRS and Short RACH
HARQ Timing
K = 4 (fixed)
DL : Async, UL :Sync
K = varying depending on Subframe Config
DL : Async, UL : Sync
Ack/Nack Feedback ModeOne Transmission one Ack/NackBundling or Multiplexed
SR/DCI 0 Timing4 msVarying
DCI 0/PUSCH Timing4 msVarying
System Information Variation

SIB1





< Subframe(UL/DL) Configuration >




< Special Subframe Length >

Special Subframe
Configuration
Length in Samples (Normal CP)
Length in OFDM Symbols (Normal CP)
DwPTS
GP
UpPTS
DwPTS
GP
UpPTS
0
6592 Ts

2560 Ts
3
10
1
1
19760 Ts

2560 Ts
9
4
1
2
21952 Ts

2560 Ts
10
3
1
3
24144 Ts

2560 Ts
11
2
1
4
26336 Ts

2560 Ts
12
1
1
5
6592 Ts

5120 Ts
3
9
2
6
19760 Ts

5120 Ts
9
3
2
7
21952 Ts

5120 Ts
10
2
2
8
24144 Ts

5120 Ts
11
1
2




Switching Points


PRACH Preamble Format

Refer to 36.211 5.7 Physical random access channel for the details.



RACH Configuration



Special Slot Usage

< RB Allocation on Special Subframe >

Refer to 36.213 7.1.7 Modulation order and transport block size determination for the details.



HARQ Timing

In case of FDD, it is pretty simple and obvious for UE to transmit HARQ ACK or NACK. UE start preparing the response as soon as it completes the decoding PDSCH and transmit it 4 ms (4 TTI) later. But in TDD, UE cannot transmit the response in such a fixed timing as in FDD. It has to wait until it gets the next chance for UL transmission and the next chance will be different depending on UL/DL configuration. Even when UE gets the chance to transmit the UL, it is may not always possible to transmit all the necessary response. For example, if UE gets too many DL subframe before the UL subframe, it will be difficult to transmit the all the reply in the UL transmission because PUCCH space is not big enough to accomodate all the HARQ ACK/NACK. So they came out with very complicated/confusing table as shown below to define HARQ response to cope with this kind of situation. In this section, I will explain how to interpret this table and figure out the exact HARQ response timing for each UL/DL configuration.



< ACK/NACK from UE for PDSCH >

Following table shows the Ack/Nack Transmission Timing from UE for the PDSCH it recieved.


Problem is how to interpret this table. Following shows how to interpret each raw of the table.

Case 1 : UL/DL Configuration 0

In case of UL/DL Configuration 0, Ack/Nack response timing for the PDSCH that is received by UE is transmitted according to the following rule.


How do you interpret this table and DL/UL correlation ?

It says
  • UE transmit Ack/Nack at subframe 2,4,7,9
  • At subframe 2, UE transmit Ack/Nack for PDSCH it received at subframe 6 in previous SFN
  • At subframe 4, UE transmit Ack/Nack for PDSCH it received at subframe 0 in current SFN
  • At subframe 7, UE transmit Ack/Nack for PDSCH it received at subframe 1 in current SFN
  • At subframe 9, UE transmit Ack/Nack for PDSCH it received at subframe 5 in current SFN

Case 2 : UL/DL Configuration 1

In case of UL/DL Configuration 1, Ack/Nack response timing for the PDSCH that is received by UE is transmitted according to the following rule.

How do you interpret this table and DL/UL correlation ?

It says
  • UE transmit Ack/Nack at subframe 2,3,7,8
  • At subframe 2, UE transmit Ack/Nack for PDSCH it received at subframe 5,6 in previous SFN
  • At subframe 3, UE transmit Ack/Nack for PDSCH it received at subframe 9 in previous SFN
  • At subframe 7, UE transmit Ack/Nack for PDSCH it received at subframe 0,1 in current SFN
  • At subframe 8, UE transmit Ack/Nack for PDSCH it received at subframe 4 in current SFN


Case 3 : UL/DL Configuration 2

In case of UL/DL Configuration 2, Ack/Nack response timing for the PDSCH that is received by UE is transmitted according to the following rule.


How do you interpret this table and DL/UL correlation ?

It says
  • UE transmit Ack/Nack at subframe 2,7
  • At subframe 2, UE transmit Ack/Nack for PDSCH it received at subframe 4,5,6,8 in previous SFN
  • At subframe 7, UE transmit Ack/Nack for PDSCH it received at subframe 9 in previous SFN and 0,1,3 in current SFN

Please try to do the same analysis for the remaining UL/DL Configuration on your own. It would be the best way for you to understand the meaning of the table clearly.


< ACK/NACK from eNB for PUSCH >


Case 1 : UL/DL Configuration 0



Case 2 : UL/DL Configuration 1



SR/DCI 0 Timing

The Time delay between SR(Scheduling Request) and DCI 0 is not clearly specified in 3GPP specification. So basically, NW can send DCI 0 in any available DL subframe after reception of SR, but depending on the eNodeB and Test Equipment some minimum time interval may be required.


DCI 0/PUSCH Timing

If UE recieves DCI 0 at subframe n, it should send PUSCH at subframe n + k where k is defined as follow. I will post some graphical explanation for this table later. Until then, give it a try on your own to understand this table.

36-213 V9.3.0 (2010-10) Table 8-2 k for TDD configurations 0-6


Issues with Debugging

What was your first impression about all the Ack-Nack report mechanism described above ?
My first impression was "So complicated !" and "So.. So.. So.. confusing".
Unfortunately.. there is more serious problem than the 'confusing things'. It is about troubleshooting issues.

Let's assume that you are using DL/UL Configuration 2. and suppose UE sent a NACK at Subframe 2.
How did you know whether the NACK is for PDSCH at subframe 4 or 5 or 6 or 8 ? (As you know, in FDD.. the answer is so simple since the ACK/NACK from the UE is always for the PDSCH that it received 4 subframe before. If it is FDD, the answer is supposed to be 'it is for PDSCH received at subframe 8 in previous SFN), but in TDD case it is different as you may guess.


Then how do you correlate the NACK to the specific PDSCH which caused the NACK. It is completely dependent on how much detailed information that your UE log or Network log provide. If UE log or Network log provide ACK/NACK information and HARQ process number for every subframe.. you can try following procedure.
    i) First, check UCI info at specific SFN and subframe number (let's label this as 'SFN_n:Subframe_2') and locate the HARQ process number that caused NACK.
    ii) Go to transmitted PDSCH list 'around' SFN_n:Subframe_2 (at this point, you would not know exactly which subframe you have to pin point out).
    iii) Look through several subframes upwards and downwards to find the subframe that is marking the same HARQ process number as you got at step i). That is the subframe that caused NACK.


Ack/Nack Feedback Mode

As described above, in TDD LTE ibe subframe can transmit ACK/NACK for multiple subframe as shown below. In the following figure as an example, UE send ACK/NACK for 4 PDSCHs in subframe 2. What should eNB do if the subframe 2 send NACK ? Does it have to retransmit the whole 4 PDSCHs ? or transmit only PDSCH which is NACKed ?

The answer to the question gets different depending on tdd-AckNackFeedbackMode setting in RRC message (e.g, RRC Connection Setup or RRC Connection Reconfiguration).
If it is set to be 'bundling', eNB should retransmit all the PDSCH. If it is sent to be 'multiplexing', eNB should retransmit the only PDSCH which is NACKed.




Followings are some of the items that is worth noticing from 3GPP 36.213 10.1.3 TDD HARQ-ACK feedback procedures (I revised the statement a little bit to make it simple and hopefully clearer)
  • For TDD UL/DL configuration 5 and a UE that does not support aggregating more than one serving cell, only HARQ-ACK bundling is supported.
  • If a UE that supports Carrier Aggregation is configured by higher layers to use HARQ-ACK bundling, PUCCH format 1b with channel selection according to the set of Tables 10.1.3-2/3/4 or according to the set of Tables 10.1.3-5/6/7, or PUCCH format 3 for transmission of HARQ-ACK shall be used.
  • PUCCH format 1b with channel selection according to the set of Tables 10.1.3-2/3/4 or according to the set of Tables 10.1.3-5/6/7 is not supported for TDD UL/DL configuration 5.
  • TDD HARQ-ACK bundling is performed per codeword across M multiple DL subframes associated with a single UL subframe n, by a logical AND operation of all the individual PDSCH transmission (with and without corresponding PDCCH/EPDCCH) HARQ-ACKs and ACK in response to PDCCH/EPDCCH indicating downlink SPS release
  • For TDD HARQ-ACK multiplexing and a subframe n with M >1, spatial HARQ-ACK bundling across multiple codewords within a DL subframe is performed by a logical AND operation of all the corresponding individual HARQ-ACKs. PUCCH format 1b with channel selection is used in case of one configured serving cell
  • For TDD HARQ-ACK multiplexing and a subframe n with M = 1, spatial HARQ-ACK bundling across multiple codewords within a DL subframe is not performed, 1 or 2 HARQ-ACK bits are transmitted using PUCCH format 1a or PUCCH format 1b, respectively for one configured serving cell.
  

You would notice the variable 'M' in many of the statement above. M is defined to be "the number of elements in the set K defined in Table 10.1.3.1-1". Following examples would give you clearer idea on the meaning of M.



System Information Variation