Home of RF and Wireless Vendors and Resources

One Stop For Your RF and Wireless Need

Chase Combining HARQ versus Incremental Redundancy HARQ

This page on Chase Combining HARQ vs. Incremental Redundancy HARQ describes Chase Combining HARQ and Incremental redundancy HARQ techniques and provides difference between Chase Combining HARQ and Incremental Redundancy HARQ techniques.

Chase Combining HARQ

In this chase combining type of HARQ, same information and parity bits are retransmitted each time. The retransmission of the same packet helps increase Eb/No at the receiver due to MRC technique. This technique is also called as repetition coding as same coded information is transmitted all the time.

Moreover at receiver previous packets are stored in a buffer; so that retransmitted packets are summed up with previously received erroneous packets before they are passed to decoder. The technique used at receiver to sum the packets is the simple MRC (maximum Ratio Combining) technique.

Buffer Size = No. of coded symbols per coded packet

Application- WiMAX as per IEEE 802.16e-2005 OFDMA Physical layer.

Chase Combining HARQ type

Fig.1,Chase Combining HARQ

Incremental redundancy HARQ

In this Incremental redundancy type of HARQ, multiple different set of code bits are generated for the same information bits used in a packet unlike chase combining type. These different sets are transmitted under different channel conditions. These sets consist of different redundancy flavors obtained by different puncturing configurations.

This scheme in which some additional redundant information bits are transmitted in each re-transmission and receiver needs to decode on each re-transmission is the IR type II HARQ.

In type III HARQ, each re-transmitted packet is self decidable.

Buffer Size = No. of coded bits of the total transmitted coded packets

Application- HSDPA as per UMTS R5 standard

Incremental Redundancy HARQ type

Fig.2,Incremental redundancy HARQ

Chase combining and incremental redundancy techniques are very useful for engineers working in physical layer development of advanced wireless technologies as per Mobile WiMAX and LTE standards.

What is Difference between

difference between FDM and OFDM
Difference between SC-FDMA and OFDM
Difference between SISO and MIMO
Difference between TDD and FDD
Difference between 802.11 standards viz.11-a,11-b,11-g and 11-n
OFDM vs OFDMA
CDMA vs GSM
Bluetooth vs zigbee
Fixed wimax vs mobile
wibro vs mobile wimax
Microcontroller vs microprocessor
FDM vs TDM
wimax vs lte
RF heterodyne versus homodyne receiver
white noise Vs. colored noise
FIR filter Vs. IIR filter
HSDPA vs HSUPA
SCPC Vs. MCPC
RS232 Vs. RS485
TD-SCDMA Vs. WCDMA Vs. CDMA2000
diff. BW DSSS and FHSS
FDMA Vs. TDMA Vs. CDMA
Diplexer versus Duplexer
R&S CMU200 Vs. Agilent 8960
rf isolator Vs. rf circulator
Sensitivity Vs. selectivity
hub Vs. switch
circuit switching Vs. packet switching
Difference between soft handover and softer handover

RF and Wireless Terminologies


Share this page

Translate this page