Phich in lte. The following list describes LTE downlink physical channels and physical signals. TTI Bundling . In Long-Term Evolution (LTE) networks, the PHICH (Physical Hybrid-ARQ Indicator Channel) is a crucial physical channel that plays a pivotal role in the implementation of Hybrid Automatic Repeat reQuest (HARQ) processes. Overhead in symbol 2 = 0 REs Jun 3, 2017 · “LTE visualization tool” is published by EventHelix in LTE — Long Term Evolution. ix) Network decode PUSCH data and send ACK/NACK via PHICH. It is divided into radio frames, and each radio frame consists of 10 subframes. x) UE decode PHICH and retransmit the data if PHICH carries NACK . PHICH resources, specified as an R-by-2 numeric matrix. Let's explore in detail the purpose and utilization of LTE PHICH. Now we will decode two other downlink channels, the PBCH (physical broadcast channel) and the PDDCH (physical downlink control channel). So we still need to allocate a certain amount of the space in conventional way. The total number of REs would be 7 PHICH groups x 3 REGs per PHICH group x 4 REs per REG = 84 REs. Table-1 LTE PDCCH channel formats The PDCCH format is used as per required size of DCI. May 16, 2024 · The details of the Physical Hybrid-ARQ Indicator Channel (PHICH) in LTE: Purpose and Role: The PHICH is a dedicated downlink-only channel in LTE. Jun 11, 2022 · These form a PHICH transmission. Physical Channel Structure. iii) PHICH Configuration. Waterfall of an LTE downlink signal, showing PHICH transmissions Resource element mapping of the PHICH. This information influences the initialization of the Hybrid Automatic Repeat reQuest (HARQ) process, ensuring efficient acknowledgment signaling and May 11, 2023 · Master Information Block (MIB) is an essential component of the Long-Term Evolution (LTE) wireless communication system. The grouping helps manage the feedback from multiple UEs, ensuring a structured and coordinated approach to HARQ processes. g, wlan, V2X, NR etc), the list of SIB is getting longer and longer. MIB on PBCH indicates whether PHICH uses normal CP or extended CP. Simply put, it is a secially designed downlink only channel which carries ACK or NACK for the PUSCH received by the network. 211 Jan 18, 2024 · Definition: PHICH, or Physical Hybrid-ARQ Indicator Channel, is a dedicated physical channel in the LTE uplink that serves as the medium for UEs to convey acknowledgment or non-acknowledgment signals to the eNodeB. Jan 18, 2024 · Definition: PHICH groups refer to a categorization mechanism used in LTE networks to organize the transmission of acknowledgment and non-acknowledgment signals over the PHICH channel. The processing step involves scrambling, modulation, layer mapping, precoding and resource element mapping at the transmitter. . Generate the PHICH complex symbols from the cell-wide settings configuration and HARQ indicator matrix. Resource Allocation for ePDCCH Dec 30, 2023 · Let's delve into the technical details of the LTE PHY layer: LTE Physical Layer Overview: Frame Structure: The LTE frame structure is based on time and frequency domains. May 1, 2014 · A Physical Hybrid ARQ Indicator Channel (PHICH) is a very important element of the Long Term Evolution (LTE), Release 8 communication system. HARQ Process: PHICH is an integral part of the HARQ process in LTE. Chapter 8. PHICH Maximum Group Number. In the previous post I showed how to decode the PHICH. See that there are 16 PHICH available, split between two PHICH groups of 8 sequences. System Frame Number: eNodeB transmits SFN value through PBCH and UE can synchronize its SFN number from this value. Via the PHICH, a Hybrid ARQ Indicator (HI) acknowledge May 3, 2021 · What is PHICH, PHICH Group, Ng Factor and Orthogonal Sequence in 4G-LTE ? PHICH PHICH stands for Physical Hybrid ARQ Indicator Channel. Jan 1, 2012 · The downlink control channels are PDCCH, PCFICH and PHICH. It is a control channel message transmitted by the eNodeB that provides necessary information for User Equipment (UE) to synchronize with the network and access the cell. Jan 18, 2024 · Understanding PHICH (Physical Hybrid-ARQ Indicator Channel) Duration in LTE In Long-Term Evolution (LTE) networks, the PHICH (Physical Hybrid-ARQ Indicator Channel) duration is a critical aspect that defines the time period during which the PHICH channel transmits acknowledgment (ACK) or negative acknowledgment (NACK) signals from the User Equipment (UE) to the eNodeB (evolved NodeB). 4G/LTE - PHY Channel. If you look into the downlink signal, you would notice that it is made up of many different components. Double-click or use the drop-down menu to set the PHICH Duration to Normal or Extended for the selected PHICH channel. PHICH (Physical HARQ Indicator channel) was used in LTE to handle uplink retransmissions and was tightly coupled to the use of a synchronous HARQ protocol, but since the NR HARQ protocol is asynchronous in both uplink and downlink the PHICH is not needed in NR. In LTE, spreading sequences are used in a PHICH group, where for normal CP and 2 for extended CP. If CFI is set to be 1 for a subframe, it means one symbol (the first symbol) at the subframe is Nov 9, 2022 · Consider that the PHICH group multiplier (Ng) is set to 1 which is equivalent to 7 PHICH groups (10 MHz – 50 RBs) then the number of PHICHs supported would be 7 (PHICH Groups) x 8 (Number of Orthogonal Sequences) = 56 PHICHs. See 3GPP TS 36. It plays a critical role in the HARQ process, allowing for the efficient retransmission of downlink data packets. 8. 4 Mhz. 3 TDD HARQ-ACK feedback procedures (I revised the statement a little bit to make it simple and hopefully clearer) This site is for everything on 4G/LTE. Aug 12, 2021 · LTE, thus, provides the PHICH resource to indicate the number of PHICH groups expressed as a fraction of the downlink system bandwidth in terms of resource blocks so that the system designer can spread the PHICH over multiple OFDM symbols. Demodulation of PDSCH (Cell-Specific Reference Symbols) / FDD (Fixed Reference Channel) / FDD PDSCH Single Antenna Port Performance (Cell-Specific Reference Symbols) / FDD PDSCH Single Antenna Port Performance Mar 3, 2011 · UE Initial Access is the process between an UE is switched on and before sending UE specific signaling or data. Number of REs in one symbol : 50*12 = 600. UE do "Non-Adaptive retransmission" if it got "HARQ feedback (PHICH=NACK)" but does not get DCI 0. 2. However, HARQ Process for Uplink in M1 is different from legacy LTE. g, PDCCH and PHICH) at each subframe. Jan 18, 2024 · In conclusion, PHICH information in the Master Information Block (MIB) in LTE networks is essential for providing UEs with the necessary details about the configuration of the PHICH channel. A normal CP means PHICH uses first OFDMA symbol belongs to a subframe. In legacy LTE, PBCH is spreaded across 6 RB bandwidth (i. 211. 212 section "5. Cell Search and Selection Receive System information Random access procedure Cell Search and Selection In order to know the cell search and selection first we have to know the physical signals (more . Followings are some of the items that is worth noticing from 3GPP 36. The HI set matrix defines a single PHICH in terms of n PHICH group, n PHICH seq, and the HARQ indicator. (In this case, UE does not care about "HARQ feedback (PHICH)", it retransmit based on DCI 0 information). Multiple PHICHs mapped to the same set of resource elements constitute a PHICH group, where PHICHs within the same PHICH group are separated through different orthogonal sequences. This matrix configures up to NPHICH individual PHICH for decoding by ltePHICHDecode. Jul 17, 2019 · However, in 5G NR, the PHICH and the PCFICH, are not needed. Each row of hires defines a single PHICH in terms of [nGroup,nSeq], where nGroup is the PHICH group index number and nSeq is the sequence index number. 213 10. Performance Requirement - Measurement Items. The PHICH, or Physical Hybrid ARQ Indicator Channel, in LTE has the role of carrying HARQ ACK/NACK responses for PUSCH. Jan 4, 2021 · LTE downlink physical layer has three control channels which are PCFICH, PDCCH, and PHICH uses in channel processing. LTE Physical Layer Overview. Range: 1 to 8. Each subframe is 1 ms long and can be further divided into time slots. Jul 3, 2013 · 3 bits for PHICH information, 1 bit to indicate normal or extended PHICH; 2 bit to indicate the PHICH Ng value; 8 bits for system frame number; 10 bits are reserved for future use; Apart from the information in the payload, the MIB CRC also conveys the number of transmit antennas used by the eNodeB. Choice: Normal | Extended. ) As the functionalities of LTE evolves and start interplay with other radio technologies (e. The PHICH groups used by a cell are always allocated to the PHICH even when they are not used to transmit hybrid-ARQ ACKs/NACKs. The Physical Hybrid Automatic Repeat Request (ARQ) Indicator Channel(PHICH) is the control channel which carries the acknowledgement (ACK/NACK), denoted as Hybrid ARQ Indicator(HI). iii) Decode PHICH channel (PHICH is also at the first symbol of the first slot). Link level performance results of PHICH for physical This site is for everything on 4G/LTE. In this case, UE retransmit the PUSCH in predefined RV and MCS without the information from DCI 0. CFI (Control Format Indicator) CFI is a indicator telling how many OFDM symbols are used for carrying control channel (e. It provides the feedback from the network to the UE about the success or failure of the reception of an uplink data transmission. This is because PHICH is transmitted with a code rate of 1/3 (repetition coding). The different steps for initial access are described below. These control channels play a key role in the correct decoding of the payload information. • PHICH configuration is part of system information transmitted on PBCH – 1 bit to indicate 1 or 3 OFDM symbols – 2 bits indicate • The PHICH which the terminal will expect the HARQ acknowledgement upon (PHICH group #, orthogonal Seq. Simply put, it is a specially designed downlink only channel Get PHIH resource information for normal cyclic prefix system subframe with 50 DL resource blocks and HICH group multiplier set to 'Sixth'. In LTE, Non-adaptive retransmissions were triggered by a negative acknowledgement on PHICH Duration. PHICH/PHICH Group. Downlink physical channels carry layer 2 information but downlink physical signals are only used by the physical layer. 1. Jan 18, 2024 · PHICH is one of the physical channels used for the implementation of Hybrid Automatic Repeat reQuest (HARQ), which is a key feature in LTE to enhance the reliability of data transmission. e, 1. The number of resource-element groups not assigned to PCFICH or PHICH is REG N . PHICH Acknowledgement Mapping. The PHICH is a dedicated downlink-only channel in LTE. May 16, 2024 · The details of the Physical Hybrid-ARQ Indicator Channel (PHICH) in LTE:. Uplink case they just used PUCCH for carrying ACK/NACK for each PDSCH it recieved. The most critical difference is that eNB does not send any HARQ ACK/NACK for PUSCH (It is understandable because there is no PHICH in LTE M2). HARQ Process for Downlink of LTE-NB(M2) is similar to legacy LTE except that each transmission would happen in repetition. ” Jan 18, 2024 · The Physical Hybrid ARQ Indicator Channel (PHICH) in LTE (Long-Term Evolution) is a crucial element designed to support Hybrid Automatic Repeat reQuest (HARQ) operations, contributing to the reliability and efficiency of data transmission. These indices are zero-based. ; Its primary purpose is to carry ACK (acknowledgment) or NACK (non-acknowledgment) signals from User Equipment (UE) to the eNodeB (base station). 8. However, HARQ Process for Uplink in M2 is different from legacy LTE. The DCI bits have 16 bit CRC attached prior to rate-1/3 channel coding & rate matching modules. Relationship between CFI and PHICH Duration. Its primary purpose is to carry ACK (acknowledgment) or NACK (non-acknowledgment) signals from User Equipment (UE) to the eNodeB (base station). How should we redesign PBCH to be fit in 1 RB bandwidth ? In legacy LTE, PCFICH and PHICH are designed to spread across the whole system bandwidth and the minimum of the whole system bandwidth is 1. Definition and Purpose: 1. One bit in the MIB indicates whether the PHICH duration is one or three OFDM symbols, and two bits indicate the amount of resources allocated for the PHICH. LTE PHICH channel REFERENCE: Document 3GPP TS 36. The CCEs availablein the system are numbered from 0 and N_CCE-1 , where N_CCE = floor(N_REG/9) . Followings are the whole SIB list as of now. Block diagram view of the physical HARQ indicator channel (PHICH) processing and associated functions in the LTE Toolbox. In the LTE Toolbox™, a HI set matrix is used to define the HI and PHICH index pair for each HI within the subframe. PHICH, PDCCH, PBCH and PHICH channels are shown on the subcarrier symbol grid. A extended CP means PHICH uses first 3 OFDMA symbols belong to a subframe. The purpose of this channel is to carry HARQ ACK/NACK for the data sent in PUSCH(UE to Network). Jan 11, 2024 · PHICH is a DL physical channel in LTE, PHICH stands for Physical HybridARQ Indicator channel. 1-1. Purpose of PHICH in LTE: 1. Jan 18, 2024 · Definition: PHICH, or Physical Hybrid-ARQ Indicator Channel, is a physical channel in the LTE uplink that is specifically designed for transmitting HARQ acknowledgment signals. Purpose and Role: . • PHICH Resource: can be 1/6, 1/2, 1, 2. 1. Are we still going to use PCFICH and PHICH in LTE-NB ? Jul 1, 2022 · This post is a continuation of my series about LTE signal analysis. This MATLAB function returns a matrix, sym, of symbols generated by the set of physical hybrid ARQ indicator channels (PHICH) in a subframe, given the cell-wide settings configuration structure, enb, and HARQ indicator set, hiset. Downlink Power Allocation . Overhead in Symbol 1 = 200 RS + 16 REs of PCFICH + 84 REs of PHICH = 300 REs. 1 . Model HARQ Indicator and PHICH This example shows how to implement the HARQ Indicator (HI) and physical HI channel (PHICH). For detailed data structure of DCI Format 0, refer to TS 36. TTI Bundling is a method in which UE transmit a PUSCH in multiple subframes in a row (4 subframes according to current sp 4G/LTE - PHY Channel PBCH (Physical Broadcast Channel) PBCH is a special channel to carry MIB and has following characteristics : PDCCH or PHICH . The PHICH is used in LTE to handle uplink retransmissions and is tightly coupled to the use of a synchronous hybrid-ARQ protocol, but since the NR hybrid-ARQ protocol is asynchronous in both uplink and downlink the PHICH is not needed in NR. Nov 28, 2010 · Figure 3 shows the PHICH transport channel and physical channel processing on hybrid ARQ data, is the spreading code for th user in a PHICH group, obtained from an orthogonal set of codes . Release 15), the largest SIB Type number is SIB24. Second, even with ePDCCH we cannot move the control information allocated in Common Search Space. The software sets the maximum group number for the selected PHICH channel based on the PHICH Allocation Oct 27, 2015 · We would like to show you a description here but the site won’t allow us. The most critical difference is that eNB does not send any HARQ ACK/NACK for PUSCH (It is understandable because there is no PHICH in LTE M1). In this article, we will delve into the details of PHICH, its purpose, functionality, and significance in the LTE network. Each PHICH group is repeated three times in frequency. HARQ is a protocol used in wireless communication systems to enhance the reliability of data transmission by incorporating mechanisms for retransmission based on The Set of 12 REs allocated to each PHICH group is divided into three quadruplets. This gives you ACK/NACK for PUSCH. Default: Normal. Jan 18, 2024 · PHICH groups are aligned with the LTE frame structure, ensuring seamless integration into LTE subframes. 3. We don't have any new mechanism to move this part to other area. Since the control format indicator (CFI) configures how many OFDM symbols are used for mapping the physical downlink control channel (PDCCH) and hence which OFDM symbols are available for the physical downlink shared channel (PDSCH), care must be taken when using an extended PHICH duration so the PHICH is not mapped into the same region as the PDSCH. Why so complex ? When I first try to understand and configure CCE index at early phase of verification, the first question poping up in my mind was "Why is it designed in such a complicated manner to determine the CCE Index (Location of PDCCH allocation) ?". For Normal PHICH duration, there are 8 PHICH sequences in one PHICH group (and therefore 4 symbols). iv) Based on the result of step i),ii), UE will calculate CCE index for PDCCH (Refere to PDCCH Decoding for detail) v) Decode PDCCH and find DCI (DCI1 or DCI1A) which is destined to the UE. 4G/LTE - Access Control Quick Reference Access Confrol (ac-Barring, SSAC, EAB, Cell Barring) PHICH/PHICH Group Oct 22, 2017 · Then there are PHICH groups and each PHICH group occupies 3 REGs or 12 REs. May 31, 2023 · The Physical Hybrid ARQ Indicator Channel (PHICH) is an essential component in the Long Term Evolution (LTE) wireless communication system, which is designed to provide high-speed data transmission for mobile devices. The PDCCH supports multiple formats as listed in Table 6. iv) Transmit every 40 ms , repeat every 10 ms . Overall flow can be illustrated as follows. It is transmitted periodically by the eNodeB. The impact of PHICH groups on LTE performance includes improved feedback processing, resource optimization, and coordinated communication, ultimately contributing to the reliability and responsiveness of the HARQ process in LTE networks. First, we still need the symbol 0 for PCFICH and PHICH. Jan 18, 2024 · Understanding PHICH (Physical Hybrid-ARQ Indicator Channel) in LTE. PHICH stands for Physical channel HybridARQ Indicator Channel. We first started with around 12 SIBs and now (as of Jan 2020. , and the I/Q branch) is given by the number of the 1st RB upon which the HARQ Process for Downlink of M1 is similar to legacy LTE except that each transmission would happen in repetition. In normal case, when network send a grant (DCI 0), UE transmit PUSCH at only one specific subframe (4 ms after the DCI 0 reception). This site is for everything on 4G/LTE. Followings are The performance analysis of PHICH LTE-FDD control channels was presented in [8] on a theoretical base only. 4 Mhz). There are two types of frame structure in the LTE Long Term Evolution standard, Type 1 and Type 2. The set of 3 REGs used by a PHICH transmission is called a PHICH group. MasterInformationBlock ::= SEQUENCE { dl-Bandwidth ENUMERATED { n6, n15, n25, n50, n75, n100}, phich-Config PHICH-Config, systemFrameNumber BIT STRING (SIZE (8)), spare BIT STRING (SIZE (10)) } Following is the cycles in which MIB and SIB is transmitted. LTE The software sets the maximum group number for the selected PHICH channel based on the PHICH Allocation selection. If the Ng parameter is 1 then there will be 7 PHICH groups in 10 MHz channel so the total PHICH overhead will be 12*7=84. Type 1 uses Frequency Division Duplexing (uplink and downlink separated by frequency), and TDD Time Division Duplex: A duplexing technique dividing a radio channel in time to allow downlink operation during part of the frame period and uplink operation in the The configuration of the PHICH is included in the system information, specifically in the Master Information Block (MIB) on the Broadcast Channel (BCH). For Extended PHICH duration, there are 4 PHICH sequences in one PHICH group (and therefore 2 symbols). This diagram would not show all the details but give you the big picture for the procedure. eretsrkgqfdfjyrfssbmoheimbitbodzfxfompba