In one embodiment, upstream transmission throughput in a cable network is markedly increased by moving up the US/DS frequency split by approximately an order of magnitude to a few hundred MHz. Additional transceivers (carriers) may be implemented to take advantage of the broader spectrum. A block of multiple upstream carriers (FIG. 2A) are associated to form a single logical upstream providing a high-bandwidth, in-order packet stream. The carriers have a common start time (704), pursuant to a single MAP message, and operation synchronously to transmit an upstream transmission frame (250). They may use OFDM or discrete carriers. A convergence layer (350) assembles the data from all of the upstream channels (320,322,324) for presentation to the MAC layer logic (308,310) as a single, serial, high-speed transmission from the CM.