SoftHM: A Software-Based Hierarchical Modulation Design for Wireless System

Weiwei Chen, Yunhuai Liu, Tian He

Research output: Contribution to journalArticlepeer-review


Hierarchical Modulation (HM) is quite efficient for multimedia broadcast in wireless networks. It exploits the wireless broadcast advantage and allows a transmission to reach different users with various qualities. However, existing HM related schemes are based on specially designed hardware, leading to extra hardware and deployment cost in practice. As a remedy for this, we design and implement a software-based HM scheme, named as SoftHM. By carefully tuning the Physical Layer input of a packet (a sequence of '0' or '1' bits, known as PHY payload), a transmitter simply broadcasts the packet with a single rate (e.g., 54Mbps, the highest rate in 802.11g WLAN), while diverse receivers can decode and extract different amount of information (with different reception rate, e.g., 12Mbps or 54Mbps) from it based on their link qualities. Reverse engineering techniques are adopted so that SoftHM works in a plug-in mode, offering it high potentials for wireless systems without any changes in existing modulation and coding modules. We implement SoftHM based on Universal Software Radio Peripheral (USRP) B210 and Commercial of the Shelf (COTS) Wi-Fi devices. Both rigorous analysis on its performance and comprehensive implementation-based experiments show that compared with the traditional time-sharing approach, to support low-quality users with the same bandwidth, high-quality users in SoftHM achieve 111.1% to 616.7% higher throughput. Likewise, to serve high-quality users with the same bandwidth, low quality users in softHM achieve 176.9% to 390.9% higher throughput.

Original languageEnglish (US)
Article number9286822
Pages (from-to)452-464
Number of pages13
JournalIEEE/ACM Transactions on Networking
Issue number1
StatePublished - Dec 8 2020

Bibliographical note

Funding Information:
Manuscript received September 20, 2019; revised June 4, 2020; accepted November 10, 2020; approved by IEEE/ACM TRANSACTIONS ON NET-WORKING Editor M. Li. Date of publication December 8, 2020; date of current version February 17, 2021. This work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant 61702175 and in part by the Natural Science Foundation of Hunan Province, China, under Grant 2018JJ3075. (Corresponding author: Weiwei Chen.) Weiwei Chen and Tian He are with the Department of Computer and Electrical Engineering, Southeast University, Nanjing 214135, China (e-mail:;

Publisher Copyright:
© 1993-2012 IEEE.


  • Hierarchical modulation
  • PHY layer payload design
  • mobile communication system
  • modulation and coding scheme
  • signal emulation


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