# Approximate Networking for Universal Internet Access
## 4 Case Study: Approximate 5G Networks in Rural/Low Income Areas
Adapted from resources made available by the European Telecommunications Standards Institute (ETSI), ([[http://www.etsi.org/](http://www.etsi.org/)]([http://www.etsi.org/](http://www.etsi.org/))). Figure 9: Spectral energy vs. energy efficiency trade-offs for various wireless technologies (Adapted from [63]). but slightly more populated, rural areas of Zimbabwe. This shows the viability of a low-cost but still functional approximate 5G networking service. Another way we can adopt approximate networking in 5G in rural and low-income regions is to allow more simultaneous transmissions by multiple users in each orthogonal resource block (be it a time slot, a frequency channel, or a spreading code) using non-orthogonal multiple access (NOMA). NOMA is now being considered as a front runner 5G technology since it is compatible with conventional orthogonal multiple access techniques such as TDMA and OFDMA. NOMA can allow for a context-appropriate tradeoff by catering to varied channel conditions at the users and by allocating more power to the user with poorer channel conditions (or adjusting the power to facilitate the respective context-appropriate QoS requirements). Using the cognitive radio NOMA (CR-NOMA) variant, it can be ensured that some or all of the user's QoS requirements are satisfied. NOMA also allows chunking of users into multiple groups which can then be served in the same orthogonal block using multi-carrier NOMA, and different groups are allocated different orthogonal resource blocks. This can facilitate management of context-appropriate trade-offs for a large numbers of users that can be logically organized in different user classes/groups. Community networking and resource pooling is another enabling general architectural tool for rural area 5G networking [66]. These efforts are being given a boost by open source technologies and plummeting prices of commodity hardware, e.g., the introduction of low cost software defined radios and open source softwares such as OpenBTS have made community cellular very feasible for rural areas. Using such technologies, community cellular networks can be built in rural area networks in a do-it-yourself (DJY), bottom-up fashion. In contrast to a traditional GSM macrocell for rural areas, which can cost around 500,000 USD; [PERSON] et al. [67] have shown a complete deployment of functional 2G community base station in rural Papua, Indonesia, at a much cheaper price of around 10,000 USD. The study showed that 187 subscribers were served with a cheap 10,000 USD base station, thereby providing 830 dollars as monthly revenue with 368 dollars as profit. The GSM band for the project was not purchased due to high spectrum cost and the cell was operating in conjunction with the government officials. This non-availability of legal spectrum can be tackled by exploiting the GSM whitespaces discussed in [68]. It can be anticipated that recent approximate computing hardware advances will soon permeate networking solutions, particularly with 5G appliances becoming virtualized and running as software appliances on cloud data centers with the increased adoption of cloud computing and NFV. The Neural Processing Unit (NPU) is a prominent example of new approximate computing hardware, which can provide significant benefits such as an average speedup and energy savings of 2.3\(\times\) and 3\(\times\) respectively with relatively few errors. NPUs have been shown to provide these gains on almost all type of program applications, including signal processing, image processing, machine learning, graphics, and gaming. [31] has tested the gains of NPUs on these applications including Fast fourier Transform which is the one of the most important task of multicarrier communication such as OFDM. Huawei also recently announced Kirin 970, a smart phone processor featuring a dedicated NPU for superior performance and efficiency [69].