TELECOMMUNICATION ~ Difference between cable Internet and ADSL
ADSL modems and cable appear to be cost-effective methods of providing broadband network services. The key difference between ADSL modem and cable is that ADSL modem uses twisted pair cables to provide both voice and data services. Whereas, the cables are coaxial cables.
In addition, the theoretical transport capacity of coaxial cable is several hundred times greater than twisted pair cable.
Definition of ADSL:
Asymmetric Digital Subscriber Line (ADSL) used to provide broadband services. It requires two modems, one at the source, i.e. the public operator's exchange, and the other at the subscribers' premises. It transmits telephone and Internet services over the same twisted pair cable.
ADSL is asymmetric meaning that it provides different downstream and upstream speeds where the downstream speed is significantly higher than the upstream speed. The downstream bandwidth is increased by using this unequal bandwidth partitioning which eliminates crosstalk between downstream channels of the same amplitude.
The main advantage of ADSL is that its bandwidth is not shared between users. ADSL can cover the distance up to 18000 feet. The ADSL modem provides a frequency range of 25 kHz -1.1 MHz. It provides a maximum downlink speed of up to 200 Mbps.
Definition of Cable:
Cable operates on HFC (Hybrid Fiber Coax) networks and uses coaxial cable. The major disadvantage of the strategy that shares the bandwidth between users, which increases the overhead. The cable must be able to filter different traffic such as LAN broadcasts, DHCP traffic and ARP packets, etc.
The tree topology is used in the cable network. In this strategy, if the sender and receiver are on the same network, the uplink broadcast traffic would be received by any connected host, for this reason, the strategy is very insecure. Cable (IEEE 802.14) provides isochronous access and instantaneous access. To resolve the collision, it uses the first FIFO transmission rule, the priority and the n-ary tree retransmission rule.
Unlike ADSL, the distance between the user and the ISP does not affect the signal transmission rate. Cable offers a frequency range of 54 to 1000 MHz. It can provide a maximum downlink speed of up to 1.2 Gbps, depending on the manufacturer and company.
Key differences between ADSL and cable:
- ADSL modem uses twisted pair cable while cable is coaxial cable.
- ADSL can provide speeds up to 200 Mbps. On the other hand, cable can provide speeds up to 1.2 Gbps.
- Cable is not secure when the broadcast signal is received on all hosts present in the particular branch. In contrast, ADSL modem offers security because each user has a dedicated connection.
- The telephone system is generally more reliable than cable because, in case of a failure, the telephone system has a backup power supply and continues to work. On the contrary, any power failure in the cable can stop the system instantly.
- The frequency range provided in the ADSL modem is from 25 KHz to 1.1 MHz while the cable provides a frequency range between 54 and 1000 MHz.
In Short:
Cable offers high speed services compared to ADSL modem, but ADSL modem provides a security mechanism to the user while cable does not. In the case of cable, the bandwidth is shared among users, which degrades the transmission speed when a large number of users access the services simultaneously.
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