Baseband unit with adaptive fronthaul link for a distributed radio access network

A baseband unit (BBU) for use with a remote radio unit (RRU) in a distributed radio access network (RAN) and coupled to a core network, the BBU comprising:

• a processor;
• one or more memory devices coupled to the processor, and storing instructions to configure the processor;
• and
• interface circuitry coupled to the processor and a fronthaul link;
• the processor configured to:
• perform at least a second-level protocol of the RAN;
• communicate over the fronthaul link with the RRU using an adaptive fronthaul protocol;
• determine an indicator of fronthaul link quality;
• and
• dynamically change one or more parameters of the RAN based on the indicator.

A method, performed by a baseband unit (BBU), for facilitating communication between a core network and a remote radio unit (RRU) in a distributed radio access network (RAN), the method comprising:

• performing at least a second-level protocol of the RAN;
• communicating over a fronthaul link with the RRU using an adaptive fronthaul protocol;
• sending setup information to the RRU that identifies a set of receivable tones;
• and
• sending tone information to the RRU over the fronthaul link that identifies at least one tone, included in the set of receivable tones, that is useable to identify frequency-domain information to discard during creation of the fronthaul uplink information.

A method, performed by a baseband unit (BBU), for facilitating communication between a core network and a remote radio unit (RRU) in a distributed radio access network (RAN), the method comprising:

• performing at least a second-level protocol of the RAN;
• communicating over the fronthaul link with the RRU using an adaptive fronthaul protocol;
• and
• sending tone information to the RRU over the fronthaul link that identifies a set of reportable tones to use in creation of the fronthaul uplink information;
• wherein the tone information comprises a first tonemap descriptor that describes a set of reportable tones associated with a first time period and a second tonemap descriptor that describes a set of reportable tones associated with a second time period.

A method, performed by a baseband unit (BBU), for facilitating communication between a core network and a remote radio unit (RRU) in a distributed radio access network (RAN), the method comprising:

• performing at least a second-level protocol of the RAN;
• communicating over the fronthaul link with the RRU using an adaptive fronthaul protocol;
• sending tone information to the RRU over the fronthaul link that identifies a set of reportable tones to use in creation of the fronthaul uplink information;
• and
• generating a first tonemap descriptor according to the adaptive fronthaul protocol;
• the tonemap descriptor comprising:
• a base type with parameters;
• a unary operator and a second tonemap descriptor;
• or
• a binary operator, a third tonemap descriptor, and a fourth tonemap descriptor;
• wherein the tone information comprises the first tonemap descriptor.

A method performed by a baseband unit (BBU), for facilitating communication between a core network and a remote radio unit (RRU) in a distributed radio access network (RAN), the method comprising:

• performing at least a second-level protocol of the RAN;
• communicating over the fronthaul link with the RRU using an adaptive fronthaul protocol;
• adaptively decompressing fronthaul uplink information received from the RRU over the fronthaul link using the adaptive fronthaul protocol to create decompressed fronthaul uplink data;
• processing the decompressed fronthaul uplink data to provide appropriate information to the second level protocol;
• determining a quantization level of the fronthaul uplink information;
• and
• expanding the fronthaul uplink information to a native quantization level to adaptively decompress the fronthaul uplink information.

A method, performed by a baseband unit (BBU), for facilitating communication between a core network and a remote radio unit (RRU) in a distributed radio access network (RAN), the method comprising:

• performing at least a second-level protocol of the RAN;
• communicating over the fronthaul link with the RRU using an adaptive fronthaul protocol;
• adaptively decompressing fronthaul uplink information received from the RRU over the fronthaul link using the adaptive fronthaul protocol to create decompressed fronthaul uplink data;
• processing the decompressed fronthaul uplink data to provide appropriate information to the second level protocol;
• receiving complex frequency-domain information in a shared-exponent floating-point format for at least some time periods in the fronthaul downlink information, the fronthaul uplink information comprising a first mantissa value, a second mantissa value, and a shared-exponent value;
• reconstituting a first frequency-domain sample having the first mantissa value and the shared-exponent value;
• and
• reconstituting a second frequency-domain sample having the third mantissa value and the shared-exponent value.

A method, performed by a baseband unit (BBU), for facilitating communication between a core network and a remote radio unit (RRU) in a distributed radio access network (RAN), the method comprising:

• performing at least a second-level protocol of the RAN;
• communicating over the fronthaul link with the RRU using an adaptive fronthaul protocol;
• and
• compressing the data comprising a first complex frequency-domain sample and a second frequency-domain sample into a shared-exponent format that comprises a mantissa value for a first frequency-domain sample, a mantissa value for a second frequency-domain sample, and a single shared-exponent value for the first frequency-domain sample and the second frequency-domain sample;
• wherein the fronthaul downlink information comprises the frequency-domain information in the shared-exponent format.

A method, performed by a baseband unit (BBU), for facilitating communication between a core network and a remote radio unit (RRU) in a distributed radio access network (RAN), the method comprising:

• performing at least a second-level protocol of the RAN;
• communicating over the fronthaul link with the RRU using an adaptive fronthaul protocol;
• and
• sending frequency-domain information over the fronthaul link to the RRU using the adaptive fronthaul protocol, the frequency-domain information comprising:
• a tonemap descriptor describing a set of tones to be used by the RRU to generate a radio frequency signal for transmission to the wireless terminal;
• and
• data identifying modulation symbols for tones of the set of tones, and times associated with the modulation symbols.