Qualcomm Inc. announced plans to deliver its first chip for the next generation of cellular networks, angling to be ready as some carriers roll out versions of 5G services by 2018.

The San Diego-based company said it expects the forthcoming Snapdragon X50 modem chip to be available in sample quantities in the second half of 2017 and to deliver download speeds of up to 5 gigabits per second. That is roughly 100 times faster than peak speeds claimed by most networks that use the fourth-generation technology called LTE, for long-term...