HARQ is a technique that combines error correction codes with automatic repeat requests (ARQ). It allows errors that are uncorrectable by the error correction code alone to be corrected through retransmissions. There are two main types of HARQ - Type I adds error detection and forward error correction to each message, while Type II alternates between message bits and error detecting parity bits. Soft combining at the receiver improves performance by combining incorrectly received blocks with retransmissions. Incremental redundancy, used in technologies like HSDPA, improves performance over chase combining by sending different coded bits with each retransmission. HARQ is used in mobile networks to provide high speed data transmission.
Explain LTE RACH Configuration and Capacity.
My Question:
- How many UE preambles can be handled in 10 ms frame by eNodeB?
- How many UE preambles can be handled in T300 by eNodeB?
Explain LTE RACH Configuration and Capacity.
My Question:
- How many UE preambles can be handled in 10 ms frame by eNodeB?
- How many UE preambles can be handled in T300 by eNodeB?
In this paper, we discussed about LTE system throughput calculation for both TDD and FDD system.
3GPP LTE technology support both TDD and FDD multiplexing. The paper describes all the factors which affect the throughput like Bandwidth, Modulation, UE category and mulplexing. It also describes how we get throughput 300Mbps in DL and 75Mbps in UL and what are assumptions taken to calculate the same.
Paper describes the steps and formulae to calculate the throughput for FDD system for TDD Config 1 and Config 2.
The throughput calculations shown in this paper is theoretical and limited by the assumptions taken to calculate for calculations
This slide for your understanding on LTE !
LTE, the wireless access protocol for 4G mobile network service, has evolved from GSM and WCDMA based on 3GPP!
The contents of this slide is below;
I. LTE Introduction
II. LTE Protocol Layer
III. SAE Architecture
IV. NAS(Non Access Stratum) Protocols
V. EPC Protocol Stacks
With my regards,
Guisun Han
This is presentation by Keysight technologies on 5G NR Dynamic Spectrum Sharing. Very well articulated presentation as always by Keysight. Details on the 3GPP support for NR DSS implementation in LTE bands in Rel 15 and Rel 16.
This second webinar discusses LTE Air Interface, the link between a mobile device and the network, and a fundamental driver of the quality of the network.
In this paper, we discussed about LTE system throughput calculation for both TDD and FDD system.
3GPP LTE technology support both TDD and FDD multiplexing. The paper describes all the factors which affect the throughput like Bandwidth, Modulation, UE category and mulplexing. It also describes how we get throughput 300Mbps in DL and 75Mbps in UL and what are assumptions taken to calculate the same.
Paper describes the steps and formulae to calculate the throughput for FDD system for TDD Config 1 and Config 2.
The throughput calculations shown in this paper is theoretical and limited by the assumptions taken to calculate for calculations
This slide for your understanding on LTE !
LTE, the wireless access protocol for 4G mobile network service, has evolved from GSM and WCDMA based on 3GPP!
The contents of this slide is below;
I. LTE Introduction
II. LTE Protocol Layer
III. SAE Architecture
IV. NAS(Non Access Stratum) Protocols
V. EPC Protocol Stacks
With my regards,
Guisun Han
This is presentation by Keysight technologies on 5G NR Dynamic Spectrum Sharing. Very well articulated presentation as always by Keysight. Details on the 3GPP support for NR DSS implementation in LTE bands in Rel 15 and Rel 16.
This second webinar discusses LTE Air Interface, the link between a mobile device and the network, and a fundamental driver of the quality of the network.
In sending data, a transmission will experience a damage or an error in the delivery process. Corrupted data will not be used for their intended purpose. Stop-and-Wait methods of Automatic Repeat Request is a method that is applied to correct errors in the process of sending the frame at the time of transmission. Data transmission is always done between the sending computer and the receiving computer. This method ensures that information is not lost due to packet drops and that the received packets in the correct order. This is the simplest type of method Automatic Repeat Request. Stop-and-Wait method will automatically fix corrupted data occurs in the transmission process. This method works by calculating the waiting time and timeout on both computers. If the data packets successfully sent and the recipient receives the data properly, then it will send an acknowledgment to the sender. It states that the transmission was not a failure or none of the bits sent change from 0 to 1 or vice verse. Timeout function is to record how long the computer wait if there is incongruity at the time of delivery. After a specified time limit runs out, either framed or acknowledgment will be sent again to correct the mistake.
In the world of technology is already integrated into the network must have a data transmission process. Sending and receiving data communications systems do not avoid mistakes. Packets of data sent from the server to the client computer always have an error in transmission. These shipments have leaks that occur due to changes in voltage, frequency or impact. One of the methods used to detect and correct errors in data transmission is the Hamming method. This method will check bit errors in delivery. Hamming is to do the process at fault detection, and then the error will be corrected so that the arrangement of the bits will go back to the bit sequence before the data is sent. With the application of this method, the data transmission process will avoid mistakes. Data will be saved to the destination.
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Error detection uses the concept of redundancy, which means adding extra bits for detecting error at the destination.
Parity Check is one of the Error Correcting Codes.
Here you are an interesting explanation about HSPA Technology. The High Speed packet Access is the combination of two technologies, one of the downlink and the other for the uplink that can be built onto the existing 3G UMTS or W-CDMA technology to provide increased data transfer speeds.
The original 3G UMTS / W-CDMA standard provided a maximum download speed of 384 kbps.
The project was a study based report on the RAN evolution path of 2.5G EDGE Networks to HSDPA. HSDPA is a 3.5G wireless cellular system, a cost-efficient upgrade to UMTS systems and promises to deliver performance comparable to today’s wireless LAN services, but with the added benefit of mobility and ubiquitous coverage. It can offer data rates of up to 14.4 Mbps which is far beyond what 2.5G and 3G cellular systems could offer. The project focuses on a two-step upgrade, first from GSM towards the deployment of UMTS/WCDMA and then towards HSDPA. It begins a new era of “Mobile broadband” services and faces competition from “WiMAX” – but with GSM services having an obvious upgrade path to WCDMA, HSDPA seems to be leading the market in several parts of the world. HSDPA is an extremely cost-effective path to higher data rates and provides more efficient use of valuable spectrum. It enables operators to compete effectively in increasingly converged markets and satisfy the need for enhanced QoS in an efficient and cost-effective manner.
This presentation discusses about the WCDMA air Interface used in 3G i.e. UMTS. This Radio Interface has great capability on which Third Generation of Mobile Communication is built, with backward compatibility.
Fault tolerant wireless sensor mac protocol for efficient collision avoidancegraphhoc
In sensor networks communication by broadcast methods involves many hazards, especially collision. Several MAC layer protocols have been proposed to resolve the problem of collision namely ARBP, where the best achieved success rate is 90%. We hereby propose a MAC protocol which achieves a greater success rate (Success rate is defined as the percentage of delivered packets at the source reaching the destination successfully) by reducing the number of collisions, but by trading off the average propagation delay of transmission. Our proposed protocols are also shown to be more energy efficient in terms of energy dissipation per message delivery, compared to the currently existing protocol.
PARTIAL HARQ RETRANSMISSION FOR BROADCAST IN FADING CHANNELScsandit
In this paper, we study the feasibility of a hybrid scheduling approach for broadcast systems in frequency selective fading channels. The hybrid scheduling approach consists of two
components: a first broadcast component and a second unicast component. The unicast component is activated if the mobile fails to correctly decode the packet and thus sends back a
negative acknowledge to the base station. In this paper, we show that there is an optimal modulation and coding schemeto be used for each one of the components presented. The
broadcast optimal modulation and coding scheme depends on the best alignment in fading between different receivers. On the other hand, the unicast optimal modulation and coding
scheme depends on the particular fading profile of each mobile separately.
2. Hybrid automatic repeat
request (HARQ)
HARQ is a combination of high-rate forward error-
correcting coding and ARQ error-control.
The FEC code is chosen to correct an expected subset
of all errors that may occur.
ARQ method is used as a fall-back to correct errors
that are uncorrectable using only the redundancy sent
in the initial transmission.
HARQ can be used in stop-and-wait mode or
in selective repeat mode
3. TYPES of HARQ
Simple Hybrid ARQ
Type I HARQ
Type II HARQ
o Hybrid ARQ with soft combining
Chase combining
Incremental redundancy
4. Type I HARQ and Type II HARQ
Type I HARQ, adds both ED and FEC information to
each message prior to transmission.
Type II HARQ, the message originator alternates
between message bits along with error detecting parity
bits and only FEC parity bits.
5. HARQ with soft combining
In practice, incorrectly received coded data blocks are
often stored at the receiver rather than discarded, and
when the retransmitted block is received, the two
blocks are combined. This is called Hybrid ARQ with
soft combining.
6. Chase combining
Chase combining: every retransmission contains the
same information (data and parity bits). One could
think of every retransmission as adding extra energy to
the received transmission through an increased Eb/N0
7. Incremental redundancy
Incremental redundancy: every retransmission
contains different information than the previous
one. Thus, at every retransmission the receiver gains
extra information.
8. PRACTICAL IMPLEMENTATION
An example of incremental redundancy HARQ is HSDPA:
the data block is first coded with a punctured 1/3 Turbo
code, then during each (re)transmission the coded block is
usually punctured further (i.e. only a fraction of the coded
bits are chosen) and sent. The puncturing pattern used
during each (re)transmission is different, so different
coded bits are sent at each time. Although the HSDPA
standard supports both chase combining and incremental
redundancy, it has been shown that incremental
redundancy almost always performs better than chase
combining, at the cost of increased complexity.
9. APPLICATION AREAS
HARQ is used in HSDPA and HSUPA which provide
high speed data transmission.
for mobile phone networks such as UMTS.
IEEE 802.16-2005 standard.
3GPP Long Term Evolution (LTE).
10. Wideband CDMA Air Interface: Protocol Stack
TFC Selection:
Index Terms: TF, TTI and TFC
RRC:
RRC Services and Functions AND Protocol States.
11. TF, TTI and TFC
1. Transport format (TF) defines what kind of data and
how much is sent on each transport channel in each
transport time interval (TTI).
2. Transport format combination (TFC) is a set of TFs.
Indirectly, TFC gives the data rate used.
12. Process of TFC selection:
1. The MAC layer has to choose a set of TFs, so that given
the current channel conditions, the maximum amount
of highest-priority data could be transmitted over the
air interface.
** Remarks: This is not a simple task.
2. The MAC layer itself knows from the configuration
data which transport formats and which combinations
of transport formats are valid.
** Remarks: The current channel conditions could
impose limitations on what TFCs can be used.
13. Important Considerations
1. Those combinations that could carry the highest
amount of data also need the highest transmit power
in the physical layer.
** Remarks: In a CDMA system, more data basically
means more power.
2. The more noise there is in the radio interface, the
higher the transmitting power must be.
** Remark: In a noisy environment, only some of the
TFCs can be used
14. 3.The data to be transmitted is in the data buffers in the
RLC layer.
4.The MAC layer is not allowed to choose TFCs that
require the RLC layer to add padding bits to its PDUs
to make them match with the chosen TFC (i.e., to
choose too large TFCs).
15. NOTE:
1.TF selection must be done on all DCHs, and also on
RACH and CPCH channels.
2. The TFC selection algorithm is not, and will not be,
specified by the 3GPP.
16. The conductor of the protocol stack orchestra
RRC
1. General control. This is an information broadcast
service.
2. Dedicated control. This service includes the
establishment and release of a connection and the transfer
of messages using this connection.
3. Notification. This includes paging and notification
broadcast services.
17. RRC functions
1. Initial cell selection and cell reselection.
2. Broadcast of information.
3. Reception of paging messages.
4.Establishment, maintenance, and release of RRC connection.
6. Handovers (HOs).
7. Control of requested QoS.
8.Contention resolution AND Timing advance in the TDD mode.