What is PUSCH Hopping?

By | August 1, 2013

A Simple defination of PUSCH hopping is Hopping in LTE Uplink.
Physical Uplink Shared Channel (PUSCH): is used to carry on the uplink user data. QPSK, 16QAM and 64QAM are the modulation schemes supported on PUSCH. PUSCH is mapped to Physical resource blocks in different ways depending on whether uplink frequency hopping is 23 enabled or not. The mapping also differs for different types of hopping if uplink frequency hopping is enabled.Different techniques that provide uplink diversity can be used in cases where channel dependent scheduling is not suitable. Frequency hopping is one of the techniques that can be used to enhance diversity in the 3G LTE uplink. Hopping in frequency can be performed on PUSCH (Physical Uplink Shared Channel) – the channel on which the user data is transmitted. Thus frequency hopping in the uplink can be called PUSCH frequency hopping.

Download Master Thesis on Frequency Hopping in LTE from Here

Type 1 PUSCH Hopping
Hopping based on explicit hopping information in the scheduling grant
Type 2 PUSCH Hopping
In Type 2 PUSCH hopping, the hopping bandwidth is virtually divided into sub-bands of equal width. Each sub-band constitutes a number of contiguous resource blocks.

Comparison of Type 1 and Type 2 PUSCH Hopping
Diversity
In Type 1 PUSCH hopping, there are three different hopping options with a period of only 1 subframe in case of intra and inter-subframe hopping or 2 subframes in case of inter-subframe hopping mode as explained in Section 4.2 above. A UE may perform hopping in the second slot with an offset of ½ , -¼, or ¼ of the PUSCH bandwidth with respect to the lowest index PRB in the first slot.

In summary, Type 2 PUSCH hopping gives more flexibility, frequency diversity and inter-cell interference averaging compared to Type 1 PUSCH hopping. Because of these reasons, Type 2 PUSCH hopping has been selected for a detailed study using simulations. From the two hopping modes, intra and inter-subframe hopping is selected since it allows hopping between slots in a subframe.

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