Planning Wireless Solution cover 30% of the exam syllabus.
This blog focusses on Cellular Networks (Overview and Understanding) – chapter 6.
CWISA exam does not require one to know in and out of cellular wireless networking. It only aims at making one able to make decisions required to select appropriate cellular network when designing and maintaining wireless networks. So this chapter will focus on the same and relevant only to the CWISA exam requirements.
First Mobile Phone: Motorola DynaTAC 8000x – 1983, Huge and power intensive.
According to research in 2019 more than 5 billion people have mobile phone and over 65% of them own a smart phone. I think the trend will only go up and only come down after it is replaced by the next-gen technology.
As discussed earlier, CWISA exam does not aim at intending us to help us deploy cell tower radios or configuring core cellular networks. Cell-based coverage plan is used by the cellular networks. Communications across the network function through base station transceivers communicating with local base station controller at the cell site. The base station controller connect back to a mobile switching center via wired/wireless connection
Each cell site can service multiple carriers. It can provide range of services ranging from Voice, SMS, Locationing (GPS based locationing) and Data (internet access). The Data service plays a crucial role in enablement of IoT cellular deployments.
LTE / 4G
Long Term Evolution is a next step before 5G and also known as 4G. The original 4G was established in Release 10 from the 3GPP organisation. Between 4G and 5G are Release 11, 12, 13 and 14 which provide enhancement to 4G networks. Careful planning must be done in selection of devices based on their compatibility with the technology, usually mobile devices which use LTE (4G) have fallback capability to use 3G. In years to come when 3G is phased out, the fallback option will be gone too. Same is applicable in case of 5G enabled devices. Narrowband IoT (NB-IoT) is used in Release 13 for the 4G standards.
Frequency Bands – More than 50 different frequency bands (in MHz) are used in LTE/4G deployments. The exam does not require one to memorise all the bands but should know which bands are available in their regulatory domain.
Modulation Methods – ODFM is used in general LTE/4G technology. OFDMA is used in downlink communication, and single carrier FDMA (SC-FDMA) is used in uplink communication. Each subcarrier in LTE uses QPSK/16-QAM or 64-QAM.
QPSK – 2 bits per symbol, 28000 bits per/sec
16-QAM – 4 bits per symbol, 56000 bits per/sec
64-QAM – 6 bits per symbol, 84000 bits per/sec
Devices – Primary consideration for mobile devices, backup links for uplink devices like Routers/Firewall etc. Many WBAN (Wireless Body Area Network) connect via Bluetooth to gain access to the cellular network. 5G evolution which means not 5G yet but LTE-A (advanced) offer 1Gpbs/500Mbps uplink and download speeds respectively.
Still based on 4G/LTE model with OFDM as the primary modulation scheme. 5G can also support frequency bands above 6GHz, Ultra low latency at under 1 ms, Higher data rates are some of the enhancements.
Frequency bands – These vary by the regulatory domain one is in. https://www.cablefree.net/wirelesstechnology/4glte/5g-frequency-bands-lte/ – Phase one of 5G rollouts focuses on the uses of existing bands of 4G/LTE. Phase two will begin to explore the mmWave bands.
Modulation methods – Similar to LTE/4G, however it adds support for BPSK and 256-QAM as well.
BPSK – 1 bit per symbol
256-QAM – 8 bits per symbol
The ultimate goal of 5G is a max downlink of 20 Gbps and uplink speed of 10 Gbps with 100Mbps/Downlink, 50Mbps uplink at the cell edges.
Cellular – Service Provider Network – General user case scenario where service provider network used. Some areas tend to have better cellular coverage than other.
Cellular – Private Network – A private LTE/5G cells can latch on to service provider network for backhaul or connect them to your own network. Private LTE uses unlicenced frequency bands (1.9GHz, 2.4GHz, 3.5GHz and 5GHz). The 2.4GHz and 5GHz are well known for their use in Wi-Fi networks. The 1.9GHz and 3.5GHz band are lesser known bands but may be used as well.
The CBRS Alliance is focused on promoting the use of LTE and 5G in the 3.5GHz Citizens Broadband Radio Service band. Band 48 is used by CBRS as defined by 3GPPP.